title:AirQualityManagement:ConsiderationsforDevelopingCountriesWorldBankTechnicalPaper.EnergySeries

author: Wijetilleke,Lakdasa.;Karunaratne,Suhashini,A.R.

publisher: WorldBankisbn10|asin: 0821331914printisbn13: 9780821331910ebookisbn13: 9780585224251

language: English

subjectAirqualitymanagement--Developingcountries,Air--Pollution--Environmentalaspects.

publicationdate: 1995lcc: TD883.7.D44W541995ebddc: 363.73/92/0091724

Airqualitymanagement--Developing

subject: countries,Air--Pollution--Environmentalaspects.

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Pagei

AirQualityManagementConsiderationsforDevelopingCountries

WORLDBANKTECHNICALPAPERNUMBER278ENERGYSERIES

LakdasaWijetillekeandSuhashiniA.R.Karunaratne

EnergySeries

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Pageiii

Copyright©1995TheInternationalBankforReconstructionandDevelopment/THEWORLDBANK1818HStreet,N.W.Washington,D.C.20433,U.S.A.

AllrightsreservedManufacturedintheUnitedStatesofAmericaFirstprintingApril1995

TechnicalPapersarepublishedtocommunicatetheresultsoftheBank'sworktothedevelopmentcommunitywiththeleastpossibledelay.Thetypescriptofthispaperthereforehasnotbeenpreparedinaccordancewiththeproceduresappropriatetoformalprintedtexts,andtheWorldBankacceptsnoresponsibilityforerrors.Somesourcescitedinthispapermaybeinformaldocumentsthatarenotreadilyavailable.

Thefindings,interpretations,andconclusionsexpressedinthispaperareentirelythoseoftheauthor(s)andshouldnotbeattributedinanymannertotheWorldBank,toitsaffiliatedorganizations,ortomembersofitsBoardofExecutiveDirectorsorthecountriestheyrepresent.TheWorldBankdoesnotguaranteetheaccuracyofthedataincludedinthispublicationandacceptsnoresponsibilitywhatsoeverforanyconsequenceoftheiruse.Theboundaries,colors,denominations,andotherinformationshownonanymapinthisvolumedonotimplyonthepartoftheWorldBankGroupanyjudgmentonthelegalstatusofanyterritoryortheendorsementoracceptanceofsuchboundaries.

Thematerialinthispublicationiscopyrighted.Requestsfor

permissiontoreproduceportionsofitshouldbesenttotheOfficeofthePublisherattheaddressshowninthecopyrightnoticeabove.TheWorldBankencouragesdisseminationofitsworkandwillnormallygivepermissionpromptlyand,whenthereproductionisfornoncommercialpurposes,withoutaskingafee.PermissiontocopyportionsforclassroomuseisgrantedthroughtheCopyrightClearanceCenter,Inc.,Suite910,222RosewoodDrive,Danvers,Massachusetts01923,U.S.A.

ThecompletebacklistofpublicationsfromtheWorldBankisshownintheannualIndexofPublications,whichcontainsanalphabeticaltitlelist(withfullorderinginformation)andindexesofsubjects,authors,andcountriesandregions.ThelatesteditionisavailablefreeofchargefromtheDistributionUnit,OfficeofthePublisher,TheWorldBank,1818HStreet,N.W.,Washington,D.C.20433,U.S.A.,orfromPublications,TheWorldBank,66,avenued'Iéna,75116Paris,France.

Thecoverphotographshowsfactorychimneysinaresidentialdistrict,Estonia;photographbyCurtCarnemark©1993theWorldBank;printprovidedcourtesyofMr.MichaelWishart,WorldBankExternalAffairsDepartment.

ISSN:0253-7494

LakdasaWijetillekeisaprincipalchemicalengineerintheIndustryandEnergyDepartmentoftheWorldBank.SuhashiniA.R.Karunaratneisaconsultanttothesamedepartment.

LibraryofCongressCataloging-in-PublicationData

Wijetilleke,Lakdasa,1933-Airqualitymanagement:considerationsfordevelopingcountries/LakdasaWijetillekeandSuhashiniA.R.Karunaratne.p.cm.(WorldBanktechnicalpaper,ISSN0253-7494;no.

278.Energyseries)ISBN0-8213-3191-41.AirqualitymanagementDevelopingcountries.2.AirPollutionEnvironmentalaspects.I.Karunaratne,Suhashini,A.R.,1965-.II.Title.III.Series:WorldBanktechnicalpaper;no.278.IV.Series:WorldBanktechnicalpaper.Energyseries.TD883.7.D44W541995363.73'92'0091724dc2095-3248CIP

Pagev

ContentsForeword ix

Abstract xi

Preface xiii

Acknowledgments xv

AbbreviationsandSymbols xvi

ConversionFactors xvii

ExecutiveSummary 1

EffectsofAirPollutantsonHealthandtheEnvironment

1

GreenhouseGases,AcidRain,Ozone,andChlorofluorocarbons

4

AmbientAirQualityandEmissionStandards 6

ValuationoftheBenefitsofMitigatingAirPollution 7

OptionsforMitigatingAirPollution 8

ConclusionsandRecommendations 12

1.AirPollution:AGrowingProblem 15

2.HealthandEnvironmentalEffectsofMajorPollutants,PartI:CarbonMonoxide,Hydrocarbons,OxidesofNitrogen,SuspendedParticulateMatter,andLead

21

CarbonMonoxide 21

Hydrocarbons 27

OxidesofNitrogen 30

SuspendedParticulateMatter 33

Lead 34

3.HealthandEnvironmentalEffectsofMajorPollutants,PartII:GreenhouseGases,SulfurOxides/AcidRain,Ozone,andChlorofluorocarbons

41

CarbonDioxideandtheGreenhouseEffect 41

SulfurOxidesandAcidRain 43

Ozone 48

CFCsandStratosphericOzoneDepletion 54

RelevancetoDevelopingCountries 56

Pagevi

4.AmbientAirQualityandEmissionStandards 59

AirQualityStandards 59

TheU.S.CleanAirActandAmendments 71

5.ValuationoftheBenefitsofMitigatingAirPollution 75

AHealth-BenefitsModel 76

TheCaseofThailand 77

RelevancetoDevelopingCountries 80

6.OptionsforMitigatingAirPollution 81

OptionsforReducingStationary-SourceEmissions 81

OptionsforReducingMobile-SourceEmissions 83

7.TowardanAirQualityManagementProgram 87

LegalFrameworkandInstitutionalArrangements 87

DevelopinganIntegratedProgramtoManageAirPollution

89

Glossary 93

References 97

Tables

1.1ApproximateToxicityWeightingFactorsforSelectedPollutants

18

2.1PredictedCOHbBloodConcentrationsforSubjectsEngagedinDifferentTypesofWork

22

2.2SignsandSymptomsofIncreasingCOHbLevelsinanAverageAdult

23

2.3SummaryofCOEmissionsOutlook,19802005 26

2.4ContributionofRoadTransportSectortoTotalHCEmissionsinSelectedCities

30

2.5SummaryofNOxEmissionsOutlook,19802005 32

2.6SuspendedParticulateMatterinVariousCitiesBetween1980and1984

35

3.1IncreaseinGreenhouseGases 43

3.2ConcentrationsofSO2atSelectedGEMS/AirSites,198089(mg/m3)

45

3.3OzoneLevelsinSelectedCities,1989 50

3.4EffectsofOzoneatVariousConcentrations 52

3.5HumanResponsetoSingleOzoneExposure 53

Pagevii

4.1ComparativeAmbientAirQualityStandardsof14Countries/EconomiesandTwoInternationalOrganizations

61

4.2China'sNationalAmbientAirQualityStandards(mg/m3)

62

4.3India'sAmbientAirQualityStandards(mg/m3) 62

4.4WorldHealthOrganizationGuidelinesforAmbientAirQualityStandards

63

4.5TransportSectorContributiontoNationwidePollutantEmissionLevelsinFrance,1990

64

4.6TransportSectorContributiontoAirPollutantEmissionsinSelectedCountries

65

4.7ExhaustEmissionStandardsforGasoline-PoweredLight-DutyVehiclesinSelectedIndustrializedCountries(g/km)

67

4.8Brazil'sEmissionStandardsforGasoline-andAlcohol-PoweredLight-DutyVehicles(g/km)

68

4.9Mexico'sEmissionStandardsforGasoline-PoweredMotorVehicles(g/mile)

68

4.10U.S.EmissionStandardsforLight-DutyDieselVehicles(g/mile)

70

4.11U.S.EmissionStandardsforHeavy-DutyDieselVehicles(g/BHP-hr)

70

4.12CurrentHeavy-DutyDieselPollutantLimitsinEurope(g/kWh)

71

4.13U.S.FuelSpecifications19922000,BasedonU.S.CleanAirActAmendmentsof1990

72

5.1Bangkok:EstimatedImpactsonMorbidityandMortalityof20PercentReductioninAmbientConcentrationsofSPM

77

5.2Bangkok:EstimatedImpactsonMorbidityandMortalityof20PercentReductioninAmbientConcentrationsofLead

77

5.3Bangkok:EstimatedImpactsonMorbidityof20PercentReductioninAmbientConcentrationsofSO2

78

5.4Bangkok:EstimatedImpactsonMorbidityof20PercentReductioninAmbientConcentrationsofO3

78

5.5SummaryofHealthBenefitsof20PercentImprovementinAirQualityinBangkok

78

Figures

1.1RelationshipBetweenLevelofDevelopmentandAirQuality

17

2.1UptakeofCObyBlood,aDose-ResponseCurve 24

2.2TheDramaticRiseofAromaticsinU.S.GasolinePool,197989

29

Pageviii

2.3EffectsofInorganicLeadonChildrenandAdultsLowestObservableAdverseEffectLevels

37

2.4CorrelationBetweenLevelsofLeadinGasolineandinBloodstream

38

2.5LeadPollutioninSelectedCities 38

3.1AverageConcentrationsofNO,NO2,andO3atVariousTimesofDayinLosAngeles

49

Boxes

2.1ChemicalNatureofCarbonMonoxide 25

2.2TheTrafficPoliceofJaipur,India 28

2.3ChemicalNatureofNitrogenOxides 31

2.4HarvardSixCitiesStudy 33

2.5TheEffectsofLead 39

3.1TheChemicalNatureofSulfurOxides 44

3.2SO2andEffectsofAcidRainintheCzechRepublic 47

3.3ChemistryofTroposphericOzoneFormation 49

3.4ChemistryofStratosphericOzoneFormation 54

3.5DepletionofStratosphericOzone 55

Pageix

ForewordThisstudyofairqualitymanagementfordevelopingcountriesreinforcesanimportantthemeoftheIndustryandEnergyDepartment'sworkonenergyandtheenvironmentthevalueofanearlyandproactiveapproach.Althoughsomedevelopingcountrieshaveregardedsustainedattentiontoenvironmentalissuesparticularlyonesthatdonothaveimmediate,localimplicationsaspreconditionedonfurthereconomicgrowth,alonger-runperspectiveshowsthatearlyadoptionofpoliciesforenvironmentallysaferenergyproductionandusecanallowdevelopingcountriestoresolveoramelioratesomeofthemostdifficultproblemsofindustrializationandgrowthatlowerhumanandeconomiccost.Further,goodpoliciestowardindustrialpollutionwillhelpeconomicgrowth,notreduceit.

LikeotherrecentworkintheWorldBankandelsewherethatincorporatesvaluationofenvironmentalandhealthfactorsintoeconomicappraisalcriteria,thisstudymakestheeffectsofairqualitytangibleatthelevelsoflocalproductivityandwell-being.Thestudydoesnotseeksimplytoimposetheairqualitystandardsoftheindustrialcountriesonthedevelopingcountriesbutratherarguesthatevaluationandregulatorymodelsdevelopedintheindustrialcountriescanprovideausefulbasisforfeasible,cost-effectiveairqualitymanagementprogramsthattakeaccountofthedistinctiveeconomicandepidemiologicalfeaturesofpollutionindevelopingcountries.Ataminimum,thestudysuggests,airqualitymanagementprogramsindevelopingcountriesshouldlimitemissionstocriticalpollutantloadsandprovideformaintainingandupdatingstandardsinanticipationofeconomicgrowthandtechnologicalprogress.Ultimately,thisapproachisbothsensibleandbeneficialinthelocalandglobalcontexts.

Reformsareineffectualwithoutsupportfromlegal,institutional,andregulatorystructurescapableofmonitoringandenforcingsocialgoals.Integratedairqualitymanagementprogramsarenoexception.Focusingastheydoonindustry,transport,infrastructure,energyproduction,andsocialpolicy,airqualityprogramsnecessarilyrequireacross-sectoralapproachandacommitmenttoaddresstheproblemasanationalpriority.TheBankandtechnicalassistanceprogramssuchastheEnergySectorManagementAssistanceProgramme(ESMAP)arealsoseekingtomarshalexpertiseonthesesubjects.AnIENstudynowinprogressonfuelsreformulationforreducedemissionsandaforthcomingpaperoncleancoaltechnologiesfordevelopingcountriesareamongthepublicationswearepreparingtoassistdevelopingcountriesinmakingenvironmentallyandeconomicallysounddecisionsonenergyproductionanduse.

RICHARDSTERNDIRECTORINDUSTRYANDENERGYDEPARTMENT

Pagexi

AbstractTheburningoffossilfuelsleadstotheproductionofpollutantssuchascarbonmonoxide(CO);sulfuroxides(SOx);nitrogenoxides(NOx);hydrocarbons(botharomaticsandaliphatics);lead;andinhalableparticulatessuchasdust,smoke,andfumes.Insufficientquantitiesthesepollutantscaninjurepeople,forests,andcrops.Moreover,consumptionoffossilfuelsandproductionofcertainindustrialchemicalsalsoappeartobedamagingthelayerofstratosphericozone,whichhelpsprotecttheearthfromtheharmfuleffectsofthesun'srays.Pollutionalsoappearstobedrivingthegreenhouseeffect,whichmaythreatentheoverallstabilityoftheglobalecosystem.

Althoughairpollutionismostoftenassociatedwiththeindustrializedcountries,ithasbecomeasignificantandincreasingprobleminmanydevelopingcountries,aseconomicgrowthstimulatesconsumptionoffossilfuelsforuseinindustryandtransport;pollutionlevelsinsomedeveloping-countrycities(especiallywherebasicindustriesarelocatedinmetropolitansettingsandregulationislaxorabsent)arealreadyworsethanthoseofsomeindustrialcountries.Theinhabitantsofdevelopingcountriesarealsomorelikelytosufferthedetrimentalhealtheffectsthatcanresultfrombreathingpollutedair,inpartbecausetheygenerallyspendmoretimeoutdoorsandaremorelikelytotravelinopenmotorvehicles.Thisstudyseekstoprovideabasisfordevelopingcountriestodevelopeffectiveairqualitymanagementprograms.

Thepaperbeginsbyoutliningthenatureandextentoftheproblemaswellassomebasicconceptsthatareofrelevancetodevelopingcountries(suchastoxicityweightingfactors).Chapters2and3introducetheairpollutantsofconcernanddetailtheirdetrimental

effectsonthephysicalenvironmentandonthehealthofchildrenandadults.Chapter4providesinformationontheambientairqualityandemissionstandardsofvariouscountries,includingtheUnitedStates,aswellasthoseestablishedbytheWorldHealthOrganization.Sincemostdevelopingcountrieshavenotyetestablishedairqualitystandards,industrializedcountriesprovidemostoftheexamples.Thesestandardsneednotnecessarilybeduplicatedbythedevelopingcountriesbutrathercanbeusedasguidelines.Chapter5showshowtoevaluatethebenefitsofreductionofvariousairpollutants.UsingThailandasanexample,thechaptershowshowairqualityanalysishelpedtechniciansandofficialspinpointleadandSPMashavingthemostdangerousconcentrationsintheBangkokareaandasrepresentingthebesttargetsformitigation.Chapter6looksatsomeoptionsformitigatingairpollutionfromstationaryandmobilesources.Chapter7presentsconclusionsandrecommendationsaboutairqualitymanagementstrategiesthatmaybehelpfultodevelopingcountries.

Botheconomicandenvironmentallogicargueforvigorousactiontocontrolairpollutionintheearlystagesofdevelopment,whenitisbothcheaperandmoreeffectivetodeployanti-pollutionmeasures.Conversely,failuretodevelopeffectiveairqualitymanagementsystemswillmeanworseningairpollutionatthelocalandgloballevels.

Pagexiii

PrefaceMitigatingtheadverseenvironmentalandhealtheffectsassociatedwitheconomicdevelopmentthroughtimelyandcost-effectiveprogramsshouldbeahighpriorityfordevelopingcountries,forbothlocalandglobalreasons.Thechallengesforthedevelopingcountriesaretobenefitfromtheexperienceoftheindustrializedcountries,avoidtheirmistakes,andestablishthebasisforsoundeconomicdevelopmentwhilepreservinghumanhealthandthequalityoftheenvironment.Eachcountryofcoursewillfaceuniqueproblems,butallcountriesthatwishtoensureenvironmentalqualitywillhavetomakethecommitmenttodosoahighpriority.

Unfortunately,airqualitymanagementandenhancementoftenbecomesubjectsofconcernonlywhenairpollutionreachescrisislevels.Generally,bythetimeairpollutionisrecognizedasamajorhealthhazard,thefactorsthatexacerbateitmayhavebecomeirreversibleorextremelycostlytoremedy.Developingcountriesgenerallyhavebeenmuchslowerthantheindustrialcountriesinrecognizingtherisksandintakingtechnicalstepstoreduceairpollutionfromautomobilesandindustrialfacilities.Clearly,however,theproblemhasimmediate,localeffectsaswellasglobalimplications.

Onereasonforthispatternofneglectisalackofunderstandingofthebenefitsofenhancingairquality.Thisstudydescribestheproblem,thehealtheffects,andthebenefitsthatcouldaccruefromreducingpollution.Thedataarepresentedinaconciseformsothatpolicymakers,administrators,andtechnocratsespeciallyindevelopingcountriescanfocustheireffortsondevelopingresults-orientedprograms.

Evenwhenairpollutionisrecognizedasaproblem,addressingitinitscorrectperspectiveanddefiningthescopeofremedialmeasuresarecomplextasks.Themagnitudeofthetechnicalandpolicyissuesandthecapital-intensivenatureofmanysolutionstendtodiscourageasystematizedapproach.Withoutoversimplifyingtheoptions,thisstudyattemptstopresentcost-effectiveandsystematicstrategiesforaddressingthepollutionproblem.

Iftheyhavenotdonesoalready,developingcountriesshouldpromulgateclearlegalframeworksforcontrollingairpollution.Thiswillfacilitatetheestablishmentofairqualitystandardsandregulations,alongwithagenciestomonitorcomplianceandundertakeenforcement.Amongthefirststepsshouldbeaccuratemeasurementsofambientairqualityandthecorrelationofthesemeasurementswithepidemiologicaldatatodeterminetheharmfuleffectsofairpollutionaswellasthepotentialsocialandeconomicbenefitsofreducingit.Thestudyalsoemphasizestheimportanceofinstitutionalstrengtheningandtrainingofstaffasprerequisitesforthedevelopmentofanairqualitymanagementprogramandidentifieskeyobjectivesofaneffectiveprogram.

Thestudyprovidesthebackgroundagainstwhichanairqualitymanagementprogram'ssubcomponentssuchastrafficmanagement,fuelssubstitution,fuelsreformulation,andenergydemandmanagementshouldbedeveloped.Clearlythecosts

Pagexiv

ofimplementingthesedifferentoptionswilloftenbesubstantial.Anassessmentofinvestmentrequirementsforeachoftheabove-mentionedoptionswouldbeastudybyitself,butafollow-upstudytothepresentworkwilladdressoneofthesubcomponents,fuelsreformulaiton,anditishopedthatthiswillclarifysomeofthecostsandbenefitsofprogramsneededtomitigateairpollutionandstimulatefurtherworkinthefield.

Pagexv

AkcnowledgementsThispaperisbasedonareviewofcurrentliteratureanddataonairpollution.SpecialthanksgotoMichaelWalsh;toMohanMunasingheandMadeleineNawar(PollutionandEnvironmentalEconomicsDivision,EnvironmentDepartment,WorldBank)fortheircomments;andtoPhillipsawickiandPaulWolmanfortheireditorialassistanceandhelpfulsuggestions.WordprocessingwasprovidedbyCarole-SueCastronuovo.GraphicswerepreparedbyS.A.D.SubasingheandCathyA.Kocak.

Pagexvi

AbbreviationsandSymbolsCFCs Cholorofluorocarbons

CO Carbonmonoxide

CO2 Carbondioxide

COHb Corboxyhemoglobin

g/BHP-hr

Gramsperbrakehorsepowerperhour

g/km gramsperkilometer

g/kWh gramperkilowatthour

g/l Gramsperliter

g/mile Gramspermile

g/test gramspertestkm Kilometer(103meters)

l Wavelengthoflight

n Frequencyoflight

mg/m3 Milligramspercubicmeter

nm Nanometer(10-9meters)

NOx Oxidesofnitrogen(NOandNO2)

O3 Ozone

PM10 Particulatematterof10micronsorlessinsize

ppb Partsperbillion

ppm Partspermillion

SOx Oxidesofsulfur(SO2andSO3)

SPM Suspendedparticulatematter

TSP Totalsuspendedparticulates

VOCs Volatileorganiccompounds

vol-% Volumepercent

wt-% Weightpercent

mg/m3 Microgramspercubicmeter

mm Micrometer(10-6meters)

°C DegreesCelsius

°F DegreesFarhrenheit

Pagexvii

ConversionFactorsUnitsoflength

1mile(mi)=1.6kilometer(km)

Massunits

1pound(lb.)=0.45kilogram(kg)

1metricton(t)=103Kilogram(kg)

1shortton(shton)=2000lb.=9.07x102kilogram(kg)

Pressureunits

1atmosphere(atm)=101.325kilopascal(kPa)

1psi(lb/in2)=6.895kilopascal(kPa)

Temperatureunits

1°F=1.8°C+32

Volumeunits

1liter(L)=1000cm3=10-3m3

1USgallon(gal)=3.785x10-3m3

Toconvertvolumemeasures(ppm)toweightmeasures(mg/m3)forair

pollutants,thefollowingformulawasused:

mg/m3=ppmxmolecularweightx40.91

Page1

ExecutiveSummaryAirpollutionisamajorprobleminmostcountries.Itiscausedprimarilybyenergyuseintransportationandindustry,althoughnaturealsocontributesthroughsucheventsasvolcaniceruptionsandforestfires.Thisreportdiscussesthehealthandenvironmentalimpactsofairpollution,thecostsofmitigationmeasures,andthecostsofinaction.Itconcludesbymakingrecommendationsforpreparationofanintegratedairqualitymanagementprogram.

Manufacturedgoodsandservicesaretheproductsofindustrialactivity,andvigorousindustrialactivityistheeconomicbasisformanyotheractivities,includingsocialservices.Itisthereforeimportantthatactivitiesthatraisethestandardofliving,especiallyindevelopingcountries,shouldsucceed.Thissuccess,however,shouldnotandneednotbeachievedbyturningablindeyetoenvironmentaldegradation.Economicdevelopment,ifproperlyplanned,neednotcauseextensiveorirreversibleenvironmentaldamage;conversely,environmentalprotectioncanbeachievedwithoutthwartingdevelopment.

Theconcentrationofpollutantsintheambientairhasgenerallyincreasedasurbanizationhasproceeded.Therefore,strategiestoprotectairqualitycanandshouldbeputintoplaceasdevelopmentproceeds,beforeseriousandirreversibledamageisdone.

EffectsofAirPollutantsonHealthandtheEnvironment

Moststudiesofairpollutantshavebeenbasedondatafromtheindustrializedcountries.Nonetheless,theirfindingsarehighlyrelevanttodevelopingcountriesaswell,wherehighratesofurbanizationandnonexistentorinadequateenvironmentalregulations

oftenleadtoairpollutionratesgreaterthanthoseincomparableregionsinNorthAmericaandEurope.

CarbonMonoxide

Gasolineconsumedinmotorvehiclesisthemainsourceofcarbonmonoxide(CO)inmetropolitanareas.CarbonmonoxidelevelsintheUnitedStatesincreasedfrom73millionmetrictonsin1940to100milliontonsin1973,astheU.S.motorvehiclefleetincreasedtremendously(WHO1979:23).SimilardatafromotherOECDcountriesconfirmtheCO-vehiclelinkage.Concomitantly,theinstallationofcatalyticconvertersinmotorvehiclesintheUnitedStatesreducedCOemissionsaswellasambientCOconcentrationsdramatically.Emissionsintheindustrializedcountriesaregenerallyonthedeclinebecauseofmorestringentstandardsandthemorerapidreplacementratesofoldervehicleswiththosehavingloweremissionfactors(Holdgateandothers1982;Flachsbart1992).EmissionsofCOinthedevelopingcountries,incontrast,areprojectedtoincreasefrom40percentoftheworld'ssharein1980to58percentin2005(OECD/IEA1991:56).

Page2

InhalationofCOhasdetrimentaleffectsonhumanhealthbecausetheaffinityofhemoglobininthebloodforCOisabout240timesthatofitsaffinityforoxygen(Romieu1992).Onceinhaled,COformsastrongcoordinatebondwiththeironatomoftheprotohaemcomplexinhemoglobintoproducecarboxyhemoglobin(COHb).Thiscompound,inturn,impairstheoxygen-carryingcapacityofbloodandreducestheamountofoxygenavailableinthebloodtocarryoutnormalbodilyactivities.COHblevelsofapproximately1.2to1.5percentarenormallyfoundinthegeneralpopulation,butinareasoftrafficcongestion,COHblevelsinhumanscanreach3percent.ElevatedCOHblevelsareparticularlydangerousforpeoplewithheartdiseaseorrespiratoryproblems,pregnantwomen,andinfants.

Hydrocarbons

Hydrocarbonsareorganiccompoundsconsistingmainlyofcarbonandhydrogen.Straight-chaincompoundsareknownasaliphatics;compoundshavingacyclicstructurearecalledaromatics.Hydrocarbonsareprecursorstoozoneformation.Aromaticsingasolinepromotetheformationofnitrogenoxides,andhydrocarbonsinteractwiththesenitrogenoxidesinthepresenceofsunlighttoformozone.Athighconcentrations,hydrocarbonscauseminorirritationofmucosaandhaveageneralnarcoticeffect.Benzene,a6-carbonaromatic,isamajorindustrialchemicalandisclassifiedasaknownhumancarcinogenbecauseofitslinktoadultleukemia.Formaldehydeisashort-termrespiratoryandskinirritantandapossiblecarcinogen.

Coalandpetroleumarethetwolargeorganicreservoirsfromwhicharomaticcompoundsareobtained.Petroleumisthemainsourceofbenzene,toluene,andxylene,allusedinthechemicalindustryandintheproductionofhigh-octanegasoline.Ironically,theU.S.decisiontophaseoutanotherdangerouspollutantleadatthebeginningofthe

1970s,alongwithadesireforhighergasolineoctanelevels,increasedthedemandforaromatics.Hence,beforelimitsof1percentonbenzeneand25percentonaromaticswereimposedbythe1990U.S.CleanAirActAmendments,benzenelevelshadrisentoabove5percentandaromaticstomorethan30percent(seeOxy-FuelNews1990).Maximumpermissiblelevelsofbenzeneandaromaticsinmostcountriesare3percentand30percent,respectively.

OxidesofNitrogen

GenerallyexpressedintheinclusivetermNOx,thevariousoxidesofnitrogencompriseNO(nitrogenoxide),N2O(nitrousoxide),andNO2(nitrogendioxide).Nitrogenoxidesintheatmospherereducevisibility,contributetotheformationofacidaerosols,exacerbateglobalwarming,formozoneatgroundlevel,andactascatalystsinthedecompositionofozoneintheupperatmosphere.Inpeopleexposedtothepollutantforlongperiods,nitrogendioxidealsocausesirreversiblelungdamage.Otherilleffectsincludebronchitis,chesttightness,burningoftheeyes,andheadaches.Asthmaticsareparticularlyvulnerabletotheseproblems.RecurrentexposuretohighconcentrationsofNO2ismoreharmfulthancontinuousexposuretolower-levelconcentrations.

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Bacterialactioninthesoil,volcaniceruptions,andlightningallnaturaleventsputmuchgreateramountsofoxidesofnitrogenintotheatmospherethanhumanactivities.Naturalemissionsaredilutedovertheentireplanet,however.Hence,whereasthenaturalconcentrationofnitrogendioxideisabout0.4to9.4microgramspercubicmeter(mg/m3)worldwide,theaverageannualmeaninurbanareasrangesfrom20to90mg/m3(WorldBank1988:218),illustratingboththedamagingeffectsofhumanactivityandthepotentialforremediation.

SuspendedParticulateMatter

Suspendedparticulatematter(SPM),particles10micronsorlessinsize,remainintheatmospherelongerthanlargerparticles.Intheatmosphere,SPMreducesvisibilityandreactswithotherairpollutantstocreatenewpollutants.SPMalsocontributestorespiratoryillnessesbypenetratingdeepintotherespiratorytract.Thetoxiceffectdependsontheparticle'sphysicalandchemicalnature,particularlywithrespecttogasesadsorbedonthesurfaceorabsorbedwithinit.

InhalableSPMcomesprimarilyfromthecombustionofdieselfuelintrucksandbusesandisincreasedbyotherfactors,includingpoor-qualitydieseloil,substandardengineoperationandmaintenance,andtrafficcongestion.Althoughthetoxicityofparticulatesislowerthanthatofotherairpollutants,suchaslead,largevolumesofparticulatesareemitted,andinhalableSPM,especiallyparticlessmallerthan2microns,poseamuchgreaterriskthanlargerSPMbecauseoftheirgreaterabilitytopassthroughthenaturalprotectivemechanismsofthehumanrespiratorysystemandclingtotheinnertissuesofthelungs.AGlobalEnvironmentMonitoringSystems(GEMS)studyoftheglobalspreadofparticulatesfrom1980to1984foundthatallowableSPMlevelsin37of41citiescameclosetoorexceededWorldHealthOrganization(WHO)guidelines(French1990:11).The

WorldBankestimatesthatreductionofSPMtosafelevelscouldreduceprematuredeathsby300,000to700,000annuallyindevelopingcountries(WorldBank1992:52).

Lead

Regulatoryagenciesandhealthorganizationshavenotreachedaconsensusonexactlyhowmuchleadinthebloodconstitutesleadpoisoning.Overtheyears,however,alloftheseorganizationshaveloweredthethresholdoftoxicityasnewinformationhasbecomeavailableabouttheneurologic,reproductive,andpossiblehypertensiveeffectsoflead.Leadpoisoningcanoccurevenwithoutexposuretomajordosesoflead,sincethebodyaccumulatesleadovertimeandreleasesitonlyslowly.Itisthusthetotalbodyburdenofleadthatistherelevantfactor(AgencyforToxicSubstancesandDiseaseRegistry1992:6).

Theforegoingnotwithstanding,leadintakehasmoresevereconsequencesforchildrenthanforadults.Medicalevidencenowshowsthatdevelopmentofthenervoussysteminchildrencanbeaffectedadverselyatblood-leadlevelsof10mg/dl(Agencyfor

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ToxicSubstancesandDiseaseRegistry1992:8).Neuralgicandotherdefectscausedbyleadpoisoningmaybeirreversible,andacuteexposuresometimesleadstodeath.

Adefinitecorrelationhasbeenfoundbetweenthelevelofleadingasolineandinthehumanbloodstream.Asnotedabove,leadadditivesingasolineweredrasticallyreducedintheUnitedStatesbetween1972and1984,andasharpdeclineinambientleadlevelsaswellasleadlevelsinthebloodwasobservedatthesametime(Shy1990).

Significantcontributorstoairborneleadaremetalsmelters,batterymanufacturingplants,andemissionsfromfueladditivesandleadedgasoline.Thelastisnowconsideredtobebyfarthemostseriousproblem.Althoughonlyabout10percentofallrefinedleadgoesintogasoline,suchleadmayconstitute60percentofleademissionsintotheatmosphere.Incitieswithhightrafficcongestion,thisproportionmaybecloserto90percent.

GreenhouseGases,AcidRain,Ozone,andChlorofluorocarbons

Airpollutionhaslongbeenassociatedwithurbanizationandindustrialization.Althoughmanydevelopedcountrieshavemanagedtoreducethelevelsofsomeairpollutants,others,forexampleinSouthernandEasternEurope,haveseenlevelsofairpollutionincrease.OfparticularconcernistheworseningairpollutioninthepopulouscitiesofLatinAmerica,China,India,andSoutheastAsia.Itisestimatedthatoneofeverytwopeopleintheworldwillbeanurbanresidentbytheyear2000,andoneineverythreewillliveinacityofatleast100,000inhabitants.Eightoutofevery10peoplewillliveinadevelopingcountry.Againstthisbackground,thegrowingintensityofairpollutioniscauseforrealconcern.

Whereaslocalpollutantsareprimarilyresponsibleforthe

deteriorationofurbanairquality,regionalandglobalpollutants(suchassulfuroxides,nitrogenoxides,ozone,andgreenhousegases)arethecausesofelevatedlevelsofairpollutioninresidentialurbanareas,ruraltowns,nationalparks,andrecreationalsites.Regionalandglobalpollutantsknownoboundariesandaretransportedintheairtofardistances.Thegreenhouseeffect,depletionofthestratosphericozonelayer,andacidrainarecausedbyaggregationsofregionalandglobalpollutantsemittedbydifferentandwidespreadsources.Thus,forexample,emissionsintheIndiansubcontinentorAfricacouldultimatelyaffecttherestoftheworld.

TheGreenhouseEffect

Carbondioxide(CO2),nitrousoxide(N2O),methane(CH4),ground-levelozone(O3),andchlorofluorocarbons(CFCs)absorbinfraredradiationfromtheearth,actingineffectasaninsulatingblanketthatpreventsheatfromescapingtheatmosphere.Overthepastcenturyaverageglobaltemperaturehasincreasedbybetween0.3°Cand0.6°C,whichconformswellwiththeavailablemodelsoflong-termresponsetogreenhousegasproduction.Approximately50percentofglobalwarmingisattributedtoCO2.Chlorofluorocarbonsareresponsibleforabout20percent,methaneabout16percent,and

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ground-levelozone8percent.Thebulkoftheremaining6percentorsoiscontributedbynitrousoxide(Tétrault1992).

TheIntergovernmentalPanelonClimateChange(seeTétrault1992)hasestimatedthatatthecurrentrateofproductionofCO2andtheothergases,adoublingoftheirpreindustrialconcentrationswilloccursometimeinthe21stcentury.Thepanelhasestimatedthattheaverageplanetarytemperaturecouldrisebybetween1.5°Cand4.5°Cinthisperiod.Globaltemperaturechangesof1°to2°Chavetypicallytaken1,000to10,000years,andariseof5°CwasresponsibleforbringingtheEarthoutofthelasticeage.

Drasticchangesintheglobaltemperaturecouldcauseashiftinclimaticzones,changesinpatternsofrainfall,moreextremeweatherconditions,andariseinthesealevelthatcouldseriouslyaffectlifeinmanycountries.Ifglobalwarmingcontinuesunchecked,meltingofthepolaricecapscouldraisetheoceanlevel5to6metersbytheendofthe21stcentury,floodinglow-lyingcoastalareasallovertheworld(EnvironmentalUpdate1990).

Deforestationandthecombustionofcoal,oil,andnaturalgasinjectbillionsoftonsofcarbonintotheatmosphereeachyearandareresponsiblefortheincreaseinatmosphericCO2.Theburningoffossilfuelsalonegenerates20billiontonsofCO2,annually.Agasoline-fueledmotorvehicle,housingasingle16gallontankoffuel,generatesbetween300and400poundsofCO2(DeLuchiandothers1988).Itisestimatedthatmotorvehiclesemitalmost15percentoftheworld'stotalCO2.Asdevelopingcountriesindustrialize,theiremissionswillrisesteeplyandmaycompoundenvironmentalproblemsunlessthesecountriesacttolimitemissions.

SulfurOxidesandAcidRain

Mostsulfuremissionsareintheformofsulfurdioxide(SO2)andare

producedbypublictransport,industries,andthermalpowergeneration.Extrapolationofdatafroma54-citystudyconductedbyGEMSovertheperiod198084,toinclude1.8billionurbanresidentsworldwide,foundthatwhereas625millionpeoplearoundtheworldliveinurbanareaswhereSO2levelswerewithintheWHOannualguidelinesof40to60mg/m3,upto1.2billionurbanresidentsliveinareaswheretheairqualityforSO2iseithermarginal(550millionresidents)orunacceptable(625millionresidents).

Clinicalstudiesusinghumansubjectsindicatethatchildrenandbothhealthyandat-riskadultsarevulnerabletotheeffectsofSO2.Individualswhosufferfromchronicrespiratorydiseases,suchasbronchitis,emphysema,andasthmamayexperiencecoughingandbreathingdifficultieswhenambientSO2concentrationsincreasefrom0.1to0.2ppm(U.S.Congress1987).

AtmosphericSO2combineswithwatertoproducedilutesulfurousandsulfuricacids,whichfalltoearthasacidrain.Becausetheacidsareformedhighintheatmosphere,theymaytravelasfaras1,000milesbeforeprecipitating.Untilrecently,acidrainwaslimitedtothenorthernhemisphere,withWesternEuropeandNorth

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Americaputtinganestimated90milliontonsofSO2intotheaireachyear.Theacidrainproblemhasnowintensifiedindevelopingcountriesasthesecountriesexpandtheirindustrialactivities.RecentdataindicatethreateninglevelsofsoilacidityinpartsofBrazil,Colombia,Venezuela,India,SoutheastAsia,Japan,andChina(Tétrault1992).

PlantsareverysensitivetoconcentrationsofatmosphericSO2andtothesynergisticeffectofSO2withlowlevelsofozoneornitrogenoxides.Itisestimatedthatabout75percentofEurope'scommercialforestshavesufferedfromdamagingconcentrationsofSO2(WorldResourcesInstitute1992:208).

TheindirecteffectsofSO2canbeseeninthemanylakesaroundtheworldthatcannolongersupportplantandanimallife.Acidrainisespeciallyharmfulinareaswherethebedrockisgraniteorwhereothermaterialispresentthatisincapableofneutralizingacid-forminghydrogenions.Acidrainisalsoerodingtheworld'srichheritageofoutdoorartandarchitecture,includingtheGreekruinsontheAcropolisandtheTajMahalinIndia.

Ozone

Ozoneisabluishgaswithapungentodor.Itspresenceintheatmospherecanhaveeitherharmfulorbeneficialeffectsonhumanhealthandwell-being,dependingonitsaltitude.

Ozoneatlowaltitudes(upto15kilometers)isreferredtoastroposphericozoneandisharmful.Itisformedthroughacomplicatedseriesofchemicalreactionsbetweenhydrocarbonsandnitrogenoxidesinthepresenceofsunlight.Thisozoneisthechiefconstituentofphotochemicalsmog,andevenoneortwohoursofexerciseinsmog-ladenaircanresultincoughing,painfulbreathing,andtemporarylossoflungfunction.Repeatedexposuretoozonemay

resultinpermanentlungimpairmentorthedevelopmentofchroniclungdiseases,suchaspulmonaryfibrosis.

Stratosphericozone(above15kilometers)isbeneficialbecauseitshieldstheEarthtosomedegreefromultravioletB(UV-B)radiationfromthesun.A1percentdepletionofstratosphericozoneresultsina2percentincreaseinUV-Bradiationanda4percentincreaseinskincancer(Titus1986:1).IncreasedUV-Bradiationcanalsocausecataractsintheeyesandimpairtheskin'simmuneresponses.Meteorologicalconditionsandconcentrationsofcertainindustrialchemicalscontributetothedestructionofstratosphericozone.CFCs,throughaseriesofchemicalreactions,yieldchlorineatomsthatdepletetheozonelayer.Reportsfromaroundtheworldindicatethatthestratosphericozonelayerisshrinking,adevelopmentthatcouldhaveserioushealthandenvironmentalimplications.

AmbientAirQualityandEmissionStandards

Thecreationandemissionofairpollutantsareunavoidable,butemissionsandtheirambientconcentrationsarecontrollable.Theimpactofanypollutantisdeterminedbyitsconcentrationanddurationatanyparticularlevelintheatmosphere.Airquality

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standardsessentiallyidentifylevels,withanadequatemarginofsafety,beyondwhichapollutantcancauseharm.

Emissionstandardstocontrolharmfulemissionsaregenerallylinkedtoambientpollutionconcentrations.Thesestandardsshouldbebasedonepidemiologicaldata,ambientairquality(i.e.,theconcentrationsofpollutantsinthesurroundingarea),andambientairqualitystandards.EmissionstandardssetbytheU.S.EnvironmentalProtectionAgency(EPA)havebeenadoptedbymostcountries.Someofthesestandardscouldberelaxedindevelopingcountries.WesternEuropeancountrieshaverespondedtotheirtransport-relatedairpollutionbyimplementingincreasinglyrigorousmotorfuelstandards.Gasolinespecificationsandformulationsnowconsideredessentialintheindustrializedcountriestomeetthesestringentstandardswouldrequireamajorrestructuringofrefineries.Sincetheuseofdieseloilfarexceedsgasolineconsumptionindevelopingcountriesasawhole,reformulationofgasolinetothestandardsneededinindustrializedcountriescanbefollowedatareducedpace.

Transport-RelatedEmissions

Automobiles,light-andheavy-dutytrucks,motorcycles,off-highwayvehicles,trains,aircraft,andshipsallcontributetoairpollution.ThetransportsectoristhelargestsourceofCO,HC,NOx,SPM,andleadintheatmosphere.Byfarthelargestcontributorstopollutioninmetropolitanareasareroadvehicles.

Transportemissionsareintensifiedbycongestedroads,poorvehiclemaintenance,oldvehicles,inferiorfuels,andtheincreasingnumberofvehiclesinuse.Forexample,thenumberofvehiclesinBangkokisincreasingatanastronomicalrate.Thailandaddsabout300to400newvehiclesaday(Sayeg1992:23).Thenumberofdiesel-poweredvehiclesworldwideisalsorisingquickly.Themajorconcernwithregardtodieselvehiclesisemissionofparticulates.

TheU.S.CleanAirAct

TheU.S.CleanAirActwaspromulgatedtoensuretheprotectionandenhancementofU.S.airresources.The1970Act,asamended,setsasocietalgoalofachievinggoodairqualitywithoutconsiderationofthecostsinvolved.The1990CleanAirActAmendmentstightenedpollution-controlmeasuresincities,stipulatednecessarychangesintransportationfuels,andestablishedmorestringentexhaustemissionstandards.Amongthemoresignificantchangeswasarequirementthat2.7weight-percent(wt-%)minimumaverageoxygenmustbeaddedtogasolineduringthewinterincitiesthatarenotincompliancewithfederalairqualitystandards.TheU.S.standardsmaybetoostrictforsomedevelopingcountries,buttheyshouldprovideausefulbasisfordevelopingregulationsappropriatetoeachcountry.

ValuationoftheBenefitsofMitigatingAirPollution

Untilrecently,noattemptshadbeenmadetoquantifythebeneficialimpactsofcleanair.Thebenefitsusuallywerelumpedintoanall-inclusiveterm:improvementin

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thequalityoflife.Itisimperativethatappropriatecriteriaareadoptedtomeasurethehealthandotherbenefitsofreducingconcentrationsofambientairpollution.HealthbenefitsmodelshavenowbeendevelopedintheUnitedStates,WesternEurope,andJapan.Themodelsarelessthanperfect,buttheydoprovideausefulbasisforvaluationofbenefits,andwithappropriatemodificationtheycanbeusedtoquantifybenefitsindevelopingcountries.

Thehealthbenefitsmodelisbasedonthedamage-functionapproachtoestimatingbenefits.ThispaperpresentsanevaluationofacasestudyonThailandthatusesthismodeltodeterminetheeffectsonhumansofa20percentreductioninconcentrationsofambientairpollution.Beginningwithbaselineandprojectedchangesintheconcentrationofspecificpollutants,dose-responsefunctionsfromepidemiologicalandpopulationdataareusedincalculatingchangesinavarietyofhealthendpoints.Theeconomicvalueofthesehealthbenefitsisthenestimated.A1994estimateforThailandsuggeststhatthebenefitsaccruingfroma20percentreductionofambientairpollutantscouldrangefrom$750millionto$3.1billionannually(WorldBankdata).

OptionsforMitigatingAirPollution

Althoughthemajorsourceofairpollutioninmostmetropolitanregionsisthetransportsector,exceptionstothisrulearecommon.InThailand,Mexico,thePhilippines,India,Indonesia,andKorea,largepercentagesofthecountry'sindustrialplantsarefoundwithinmetropolitanareas.Hence,thecontributionstoairpollutionofboththeindustrialandtransportsectorsmustbetakenintoaccountwhenoptionsformitigatingairpollutionarebeingstudied.

ReducingStationarySourceEmissions

Mostdevelopingcountriesarguethatverystringentemission

standardscouldhamperindustrialization,andsomehavemadecompellingargumentsforadoptingecologicallybasedemissionstandards.Suchstandardspresupposeacceptanceoftheconceptofcriticalpollutantloadsbycalculatingtheseforeachcountry.Forlargecountries,criticalpollutantloadsmustbecalculatedonanarea-widebasis.Theconceptimpliesthatdevelopingcountriescandecidetoadoptlessstringentstandardsthanhighlyindustrializedcountriesunlessepidemiologicaldataindicatethatsomeairpollutantisalreadycausinghealthproblems.Thisconceptshouldbeappliedwithcaution,ifatall.Ifacountryisindustrializingrapidly,morestringentstandardswillhavetobeadoptedinanticipationofhigherlevelsofpollution.

Airpollutionmitigationprogramsmayincludebothtechnological-andpolicy-basedchangesandwillbemosteffectiveifthechangesareidentifiedearlyinthedevelopmentcycle.

SwitchingtoNaturalGas.Switchingtocleanerfuelsisoneofthemostcost-effectivestrategiesforreducingemissions,particularlyofSO2andCO2.Thefuelofchoiceisnaturalgas,whichcontainsvirtuallynosulfurandwhosecombustionproduces

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farlessNOxthancoalorfueloil.Sincenaturalgashasahigherhydrogen-to-carbonratio,italsoproducesfarlessCO2duringcombustionthaneithercoalorfueloil.Acombined-cyclepowerplantusingnaturalgasproduces55percentlessCO2thanacoal-firedpowerplantperunitofelectricityproduced.

UsingHigher-Quality,CleanCoal.Greateruseoflow-sulfurcoalisanotheroptionfordevelopingcountriesdespitecoal'senvironmentaldrawbacks.Ifhigh-quality(i.e.,low-sulfur)coalcanbeproducedorimportedatareasonableprice,newcoal-washingtechnologiescanfurtherreduceitssulfurcontentby20to50percent.Othernewtechnologies,suchasfluidized-bedcombustionorintegratedgasificationcombined-cyclepowergeneration,alsohaveresultedinsubstantialSO2andNOxreductions(TavoulareasandCharpentier1994).

Thescrubbingofstackgasesfromcoal-firedpowerplantsalsocanreducebothSO2andNOxemissions.Scrubberscanremoveabout95percentoftheSO2andbetween70and90percentofNOxthatwouldotherwisebereleasedduringcombustion.Thecostsofinstallingscrubbersarehigh,however,especiallyforoldplants.Anotherdrawbackofscrubbersisthatlargequantitiesofsludgeandlow-gradegypsumareproducedduringthescrubbingprocess,creatingdisposalproblems.

EnhancingConservation.Energyconservationhasbotheconomicandenvironmentalbenefits.Modernizingofexistingplantsandinstallingequipmenttorecoverwasteheatforre-usetogeneratesteamorasprocessheatareenergyconservationoptionsthatalsoreduceemissionsofpollutants.Identifyingtheappropriateoptionsanddeterminingtheireconomicandenvironmentalbenefitsrequireamajorstudyofexistingfacilities,butthenecessaryinvestmentsarerelativelymodestandthebenefitssubstantial.

TappingAlternativeEnergySources.Alternativeenergysources,suchashydro,wind,solar,geothermal,nuclear,andhydrogenpowercanbesubstitutedforfossilfuels.Nuclearpowerandhydropowerarethemostcommonlyusedalternativesources.Manydevelopingcountrieshavemadesignificantprogressindevelopingtheirhydropowerelectricgeneratingcapacity.Useofnuclearpowerhasnotmademuchprogressindevelopingcountries,withthenotableexceptionofKorea.

CuttingMobileEmissions

Motortransportvehiclescontributemosttotheincreasingconcentrationofairpollutantsinmetropolitanareas.Oldandpoorlymaintainedvehicles,congestedroads,andpoor-qualityfuelsaretheprimaryreasons.Thereplacementofoldervehicleswithneweroneswithemissioncontroldevices,maintenanceofin-usevehicles,cleanerreformulatedfuels,bettertrafficmanagement,introductionorexpansionofmasstransitsystems,androadimprovementsarethebestwaystoreducesuchpollution.

ReformulatingGasoline.Theindustrializedcountrieshavedonesubstantialworkonreformulatingmotorvehiclefuels,ashavesomeofthemoreadvanceddevelopingcountries.Reformulation,however,ishighlycapitalintensive,andthe

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developmentofacost-effectiveprogramiscriticaltoensurethatresourcesareusedtomaximizeenvironmentalandeconomicbenefitswhileavoidingsecondaryproblems.

OnesuchsecondaryproblemaccompaniedtheintroductionofcatalyticconverterstoreduceemissionsofCO,HC,andNOxfrommotorvehicles,whichinturnrequiredremovaloftheleadadditivesingasolinebecauseleadinterfereswiththecatalyst.(Theinitialobjectivewastoprotectthecatalystratherthantoprotecthumanhealth.Theharmfuleffectsofatmosphericleadonlybecameanissuelater.)Tocompensateforthelossinoctaneresultingfromtheremovaloflead,oilrefineriesincreasedthelevelsofbenzeneandaromatics,which,itsoonbecameclear,werethemselvesdangeroustohealthandtheenvironment.TheEPAhasnowlimitedthelevelsofaromaticsandbenzeneingasoline,forcingrefinerstomakemajorinvestmentstocompensateforthislossinoctane.

Severallessproblematicmethodsareavailabletoboostoctane(i.e.,withoutaddingleadorbenzeneandaromatics).Forexample,moreseverereformingofnaphthaandanincreaseinthereformer'scapacitywillmakeitpossibletomeetoctanerequirements.Ifreformingaloneisinadequate,isomerizationoralkylationprocessescanbeinstalledaswell.

Thecomplexinteractionsofabatementmeasuresunderlinetheneedforcarefulappraisaloftheextentoftheproblem,especiallywhenapplyingindustrial-countrymodelstodevelopingcountries.Inmostdevelopingcountries,dieseloilconsumptiongreatlyexceedsgasolineconsumption.Sincethequantityofgasolineconsumedisrelativelysmall,theamountofleadreleasedisalsolow.Thus,unlessepidemiologicaldatashowsserioushealtheffectsfromleadorhighlevelsofleadinambientair,leadremovalmaynotbehighpriorityinmanydevelopingcountriesatthistime.Ifevidenceshowsthatleadis

asignificantproblem,however,thenitsremovalshouldreceivethehighestpriority.

AddingOxygenatestoGasoline.TheadditionofoxygenatestogasolineisnowmandatedinseveralU.S.citiesduringthewintermonths.Methyl-tertiary-butyl-ether(MTBE)istheoxygenateofchoice.MTBEprovidesadditionaloxygentocompletethecombustionprocessinadditiontoactingasanoctanebooster.TheuseofMTBEmayinvolveeitherconstructionofMTBEplantsorimportsofMTBEthatcanbeblendedintogasoline.

ReformulatingDieselOil.ThereformulationofdieseloilbyreducingitssulfurcontentwoulddecreaseemissionsofSO2andconsequentlyofsulfatesthatcontributetoSPMconcentrations.Inaddition,reductionoftheheavierhydrocarbonfractionsindieseloilbyreducingthetemperatureatwhich90volume-percentofthedieseloilisdistilledwilldecreasetheformationofparticulatesmeasuring10micronsorlessindiameter.Dieseloilreformulationisexpensive,butitshouldhavehigherpriorityindevelopingcountrieswheredieselconsumptionishigh.

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IncreasingUseofAlternativeFuels.Liquefiedpetroleumgas(LPG)andcompressednaturalgas(CNG)arecost-effectiveandenvironmentallybeneficialoptions,ifdomesticsourcesofnaturalgasandLPGareavailable.Itmayevenbecost-effectiveincountriesthatmustimportCNGandLPG.Themajorcostsarethecostsofliquefaction,regasification,andconstructionofportfacilities.Ifdemandforgascanjustifytheseexpendituresonthebasisoftheirenvironmentalbenefitsandimprovementsinthermalefficiency,CNGwillbemorethancompetitivewithdieselfuel.

End-of-TailpipeControlsandStandards.Twootheroptionsforreducingmotorvehicleemissionsareend-of-tailpipecontrols,suchascatalyticconverters,andemissionstandards.

Catalyticconverters.Twotypesofcatalyticconvertersarecommonlyinuse:oxidationortwo-waycatalysts,whichreduceCOandHCemissions;andoxidation/reductionthree-waycatalysts,whichcontrolNOxemissionsaswell.Formanydevelopingcountries,catalyticconvertersarenotahighpriority.Wherevehicleturnoverisrapid,though,catalyticconvertersshouldbeamongtheoptionsforemissionreductions.Acatalyticconverteraddsabout$600tothecostofamedium-sizedcarandsubstantiallymoreforlargervehicles.

Emissionstandards.ExperienceinOECDcountrieshasshownthatemissionstandards,ifenforced,resultinsignificantreductionsofallpollutants.Standardsmustbeestablishedfornewandin-usevehiclesindevelopingcountries,andeffectiveinspectionandmaintenanceproceduresarenecessary.Establishmentandenforcementofemissionstandardsindevelopingcountriesmaybedifficult,butwithoutthemanygainsfromfuelsreformulationorothermeasurescouldbequicklyeroded.Wherepublictransportiscommon,however,thetasksmaybeeasier.

ImprovingRoadInfrastructure.Urbanroadseverywhereareoftenso

congestedthattrafficslowstoacrawlandexacerbatesairpollution.Yetimprovingtheroadsindevelopingcountriesisoftendifficultbecausetheirmetropolitanareashaveevolvedinwaysthathamperroadconstruction.Eveniftechnicallyfeasible,suchimprovementsareoftencostlybothintermsofcapitalrequirementsandimplementationtime.Wherepossible,however,thisoptionispreferabletoanyothercapital-intensiveoption.Tominimizecosts,roadimprovementsshouldbestudiedsimultaneouslywithtrafficmanagementoptions.

TrafficManagement.Moreeffectivetrafficmanagementcaneasetrafficcongestionsignificantly.Thelargenumberofvehiclesinservice,inadequateparkingfacilities,undisciplineddrivers,frequentvehiclebreakdowns,andpoorlydesignedtrafficmanagementplanscontributetotrafficproblemsinmostcitiesindevelopingcountries.Restrictingtheuseofmainarteries,encouragingcarpools,providingincentivestousepublictransport,establishingmasstransportsystemswherefeasible(seebelow),improvingpublictransport,levyingataxoncarsenteringcitylimits,andraisingparkingfeescanallreducetheuseofautomobiles.

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Thedisincentives,suchastaxationandincreasedparkingfees,willlikelybepoliticallyunpopularandcanonlybemadepalatablebyamajorpublicrelationsefforttoeducatethecitizenryabouttheharmfulconsequencesoftrafficcongestionandairpollution.Yetwithoutatrafficmanagementstrategy,increasingmotorvehicleusewillnegateanygainsfromotherprograms.

MassTransit.Masstransitsystemsareasociallyvaluablealternativetouseofpersonalvehicles.Masstransitsystems,however,arehighlycapitalintensive,areunlikelytoyieldaprofit,andoftenmustbesubsidizedbythegovernment.Arecentstudyof20masstransitsystemsimplementedindevelopingcountriesinrecentyearsfoundthatnotonewasprofitableinpurelyeconomicterms(Allportandothers1990).However,healthbenefitswerenotfactoredintotheassessment.Whenhealthbenefitsarecounted,thereislikelytobeaneteconomicbenefit,andthiscouldprovideajustificationforstatesubsidies.

ConclusionsandRecommendations

Conclusions

Thestudyendeavorstopresenttheairqualityproblem,healthimpacts,andvalueofbenefitsandoptionsformitigatingthisproblem.Thestudyalsohighlightstheimportanceofdevelopingreliabledataonambientairquality.Inmanydevelopingcountries,thedata-gatheringsystemispoorlyfundedandthedatatendtobeweak.Epidemiologicaldataalsoarenotassembledinascientificmanner.Thus,thestatisticstodrawmeaningfulconclusionsareoftenlacking.

Developingcountrieshavebeguntoestablishairqualitystandardsonlyrecently.Mostofthemdonothaveemissionstandardsfortransportvehiclesorindustries,andmostlackinstitutionstoensurecomplianceeveniftheyhaveestablishedstandards.Finally,

environmentalregulation,compliance,andenforcementaregenerallyweakandpoorlyfunded.

Theneedtomitigatethehealthimpactsofairpollutionisincontestable,butairqualitymanagementislikelytoreceivelowerprioritythanothersocialprogramsunlessitsvalueisunderstoodbypolicymakers.Thecasestudypresentedinchapter5showsthevaluationofbenefits(andthemagnitudeoftheproblem)andunderlinesboththemethodsofvaluationandtheneedforpolicymakerstogiveairqualitymanagementhighpriority.

Thebestprogramswillensurethatenvironmentalstandards,emissionlevels,regulatorymeasures,andthelegalframeworkforenforcementandcomplianceareestablishedearlyinthedevelopmentcycle.Itisimportanttoensurethateconomicprogressdoesnotimposeunacceptablelevelsofairqualityorenvironmentaldegradation.Selectingthepropermixofoptionsandadoptingacost-,time-,andresults-orientedstrategyisfundamentaltothesuccessofanairqualityenhancementprogram.

Becauseairpollutionistheresultofmanyfactors,identifyingthefactors,selectingthemitigationmeasures,andensuringthattheseareoptimalrequiretechnical

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skillsandknowledgeofahighorder.Forexample,whentheMexicoCityairpollutionprogramwasdevelopedbytheWorldBank,Bankstaffwereassistedbyateamoftechnicalspecialistsandeconomistsfromallovertheworldandapanelwasformedtomonitortheworkofthespecialists.Theresultwasaprogramthathasnowbecomethebasisforsimilarprogramsinothercountries.

Attimes,thecostofenvironmentalmitigationmayfallmostheavilyonthesegmentofthepopulationleastabletobeartheburden.Forexample,areductionofSPMmaydictatethereformulationofdieseloil.Thecostofreformulation,ifpassedontothetransportsector,willincreasetransportationcostsparticularlyforthepoor,themostfrequentusersofbuses,andmaythereforebepoliticallyunpalatable.Insituationssuchasthese,thecostwouldhavetobepassedontothepublicasawhole,whichsuggestsataxsubsidyofsomesortaswellasfundingatconcessionaryrates.

Aneffectivemasstransitsystemcanreduceairpollutionbyreducingtrafficcongestion.Yettoassumeinfrastructuralchangesofthissortcouldbedevelopedinafewyearswouldnotberealistic.Again,ifcostsarenotknownandfinancingisunavailable,masstransitwouldonlyremainaplan.Thesameistrueoffuelsreformulation,retrofittingofvehicles,oranyotheroption.Theaboveexamplesindicatethatthedevelopmentofasuccessfulairpollutionmitigationprogramdependsonbothitstechnicalandeconomicfeasibilityanditsacceptancebythepublic.

Recommendations

TheWorldBankcanhelpdevelopingcountriesimplementfeasibleandcost-effectiveairpollutionprograms.Thisreportsuggeststhatdevelopingcountriesshouldinitiatesuchprograms,commencingwiththefollowingsteps:

Establishprogramstocollectaccuratedataonambientairquality.

Determinecurrentlevelsofvariouspollutants.

Instituteepidemiologicaldata-gatheringsystems.

Establishambientairqualitystandards.

Projectemissionlevelsintheforeseeablefuture(e.g.,15years).

Withtheassistanceofinstitutionsexpertatmodelingemissionseffectsontheambientair,projectlikelyambientconcentrationsovertheperiodselected.

Ascertainthepotentialbenefitsofreductionsofairpollutants.

Rankpollutantsinorderoftheireffectsonhealthanddevelopcost-andtime-effectiveprogramstoreducethesepollutants.

Acoordinated,comprehensiveprogramtomanageairpollutionisessentialtoensurethecost-effectivenessanddurabilityofmitigationmeasures.Airqualitymanagementprograms(AQMPs)shouldbedevelopedforeachcountryinawaysimilartothatinwhichtheEnergySectorManagementAssistanceProgramme(ESMAP)

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preparesitscountryenergystrategies.Suchacross-sectoralapproachisdesirable,asairqualitymanagementaffectstheeconomybroadly,andacoordinatedprogramcanbedevelopedonlyfromacomprehensivestudy.AcasecanbemadetojustifytheuseofUNDPorotherfundstopreparethesestudies.TheWorldBankshouldremainreadytoprovideassistancethatcountriesmayneedinthepursuitofensuringcleanair.ThetechnicalskillsandfundsrequiredtodevelopAQMPswillbesubstantial,butsowilltheultimatehealthandenvironmentalbenefits.

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1AirPollution:AGrowingProblemInbothindustrializedanddevelopingcountries,inbothurbanandruralareas,airpollutionisaseriousandgrowingproblem.InSouthAfrica'sEasternTransvaalHighveldregion,wherecoal-firedpowerstationsgenerate80percentofthecountry'selectricity,stagnantairmassesallowthebuildupofsulfurparticlesthatcometoearthinacidrain(WorldResourcesInstitute1993:420).Acidrainisresponsiblefordeadlakesinalmost7,000squaremilesofsouthernNorway(WorldResourcesInstitute1993:544)andhasaffected150,000Canadianlakes(WorldResourcesInstitute1993:576).InRiga,Latvia,emissionsfromautomobileswithoutemissioncontroldevicesaccountfor80percentofthecountry'sairpollution(WorldResourcesInstitute1993:554).ThicksmogisbecomingcommonplaceinSantiago,Chile,becauseofuncontrolledindustrialpollutionandvehicleemissions.TheamountsofsulfurdioxideintheatmosphereabovenineofIndia'stenmajorcitiesexceednationalstandards,andparticulatematterintheairabovemanyurbanregionsinIndiaexceedstheamountsfoundintheairabovecomparableregionsinNorthAmericaandEurope(WorldResourcesInstitute1993:460).

Airpollution,particularlyinurbanareas,iscausedprimarilybyproductionofelectricity,vehicularemissions,andindustrialactivities.Naturalevents,likeeruptionsofvolcanoesandforestfires,alsosendhugeamountsofcertainpollutantsintotheatmosphere.TheJune1991eruptionofMountPinatubointhePhilippines,forexample,isestimatedtohavedischarged20milliontonsofsulfateaerosolsintotheupperatmosphere,generatingconcernthatthisonslaughtmaydepletetheprotectivelayerofozoneabovethemidlatitudinalareasoftheearth(Mock1993:306307).Urbanpollution,however,islargely

anthropogenic,theresultofactivitiessuchaspassengerandfreighttransportationandtheproductionoffood,fiber,rawmaterials,andmanufacturedgoods.

Robustindustrialactivityistheeconomicbasisofallotheractivities,includingeducationandmedicalcare.Economicsuccess,however,shouldnotcomeatthecostofunacceptablelevelsofairpollution.Ifproperlyplanned,economicdevelopmentneednotresultinenvironmentaldamage.Conversely,environmentalconcernsneednotstifledevelopment.Theobjectiveofeconomicdevelopmentistoprovidethegoodsandservicesdeemeddesirabletoimprovethequalityofhumanexistence.Economic

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developmentcanbemeasured,whereasmeasurementsofthequalitiesthatcharacterizeahealthyenvironmentarestillbeingdebated.Whateverthedifficultiesofmeasurement,however,thegoalmustbeanetbenefit.

Airpollutionisnotsimplyafunctionoftheamountofpollutantsreleasedintotheatmosphere.Topography,weatherconditions,timeofday,andthekindsofpollutantsandtheinteractionsamongthemallhelptodeterminepollutionlevels.MexicoCity,forexample,liesinavalleyamonghighmountains;frequentthermalinversionstrappollutantsinthevalley(Satterthwaite1992).Ingeneral,thevolumeoftraffic,thequalityoffuel,orthemechanicaldesignofindustriesandvehiclesmaynotbesignificant,takenindividually,butaremajorcontributingfactors.Thereareclearlinkagesamongthemthatneedtobeunderstoodinordertodevelopcost-effectivemanagementofairpollution.

Theadversehealtheffectsofvariousairpollutantshavebeendocumentedinnumerousstudies.Highconcentrationsofairpollutantsinmanydevelopingcountriesleadtoincreasedillness,particularlyamongindividualssufferingfromrespiratoryproblems,andcauseprematuredeathamongtheelderly(Romieu1992).Theairpollutantsofgreatestconcernarecarbonmonoxide,hydrocarbons,sulfuroxides,nitrogenoxides,suspendedparticulatematter,lead,andsecondarypollutants,particularlyozone.Theeliminationofleadasanadditivetogasolinehashighpriority,sinceitcanhaveharmfuleffectsonthehumannervoussystem,particularlythatofchildren.Table1.1showslead'shightoxicitycomparedwithotherairpollutants.Itisestimated,forexample,thatchildrenintheBangkokmetropolitanarealoseanaverageof4IQpointsbythetimetheyreachtheageofseven,and29percentofthemhaveunhealthyamountsofleadintheirblood.Thereisacorrelationbetweenthelevelofleadingasolineandblood-leadlevels,andintheUnitedStatesandJapan,blood-lead

levelshavefallenonaveragebytwo-thirdssinceleadadditivesingasolinewerefirstreducedandthenprohibited(WorldBank1992:53).

Exposuretosuspendedparticulatematter(SPM)isanequallyseriousrisktohealth.InhalableSPM,particularlyparticleslessthan10micronsinsize,canpassthroughthenaturalprotectivemechanismofthehumanrespiratorysystem.Thesmallestparticulates(2micronsorless)arecreatedprimarilybythecombustionofpetroleumfuels.TheWorldBankestimatesthatreducingSPMtosafelevelscouldreduceprematuredeathsby300,000to700,000ayearindevelopingcountries(WorldBank1992:52).

Theconcentrationofpollutantsinambientairincreaseswithratesofurbanizationandenergyuse.Airpollutioninsomeofthenewlyindustrializeddevelopingcountriesisworsethanintheindustrializedcountries.Thisisbecauseindustriesindevelopingcountriesoftenuseoutdatedtechnologyandbecausemostvehiclestherelackemissioncontrols.Strategiesforairqualityprotectionshouldthereforebeinplaceascountriesdevelop.Figure1.1illustratestheconsequencesofapathy.Theareabetweenthesolidanddottedlinesrepresentstheconcentrationofairpollutantsthatcouldhavebeenavoidedifairpollutioncontrolmeasureshadbeenimplementedinatimelymanner.

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Althoughtheeconomiesofmanydevelopingcountriesaregrowing,thisgrowthneednotbefollowedbyadeclineinairquality.Inmanydevelopedcountries,emissioncontroldeviceshavebeguntocauseadeclineinseverepollutantlevels;similardeclinesinpollutantlevelscanbeeffectedinthedevelopingcountriesaswell.

Figure1.1RelationshipBetweenLevelofDevelopmentandAirQuality

Source:UNEPandWHO(1992).

Airpollutionmanagementprogramsareintendedtokeepairpollutantsbelowthelevelsthatwoulddamagetheenvironmentorharmthehealthofhumans.Iftheambientconcentrationofapollutantiswellbelowpermissiblelevels,theneedtocontrolemissionsofthepollutantmaynotbeurgentunlessepidemiologicaldatastronglyindicateotherwise.Anall-encompassingairpollutionmanagementprogramshouldincludeclearlydefinedobjectivesthatwouldmeetambientairqualitystandards,theidentificationofallairpollutantsandtheirsources,thelevelsofpollutantsintheambientair,andthetypesofpollutantsthatareatriskofexceedingpermissiblelevels.

Unfortunately,dataoftherequiredqualityareseldomfoundindevelopingcountries,whichoftendecideonthebasisofpoordatathatpollutionisnotaproblem.Developingascientificdatabaseandestablishingpermissiblepollutantlevelscouldtakethreetofiveyearsinmostdevelopingcountries.Theremay,however,besomepollutantsthatarealreadyatpotentiallydangerouslevels.Thus,projectstoreduceconcentrationsofsuchpollutantsshouldbestartedassoonaspossibleandneednotawaitthedevelopmentofacompletescientificdatabase.

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Thecollectionofascientificdatabase,establishmentofrealistictargets,anddevelopmentofacomprehensiveprogramrequireastronginstitutionalandlegalframework.Implementatingaprogramwillrequirethemonitoringofactivitiesinallsectorsoftheeconomytoensurethatfacilitieswithanti-pollutiondevicesaredesigned,built,andoperatedcorrectly.

Table1.1ApproximateToxicityWeightingFactorsforSelectedPollutantsPollutant RelativeweightLead 85NOx 4.7PM10 2.3VOCs 1.8SOx 1.4Dust 0.9CO 0.04

Note:PM10=particulatematterof10micronsorlessinsize.VOCs=Volatileorganiccompounds.Source:1992WorldBankdata.

Thegovernmentsofmanydevelopingcountriesoftencomplainaboutthestringentindustrialemissionstandardsstipulatedbymostinternationalagencies,includingtheWorldBank,asaconditionforprojectassistanceandfinancing.Thecostofpollutionabatementdeviceshassometimespreventedtheimplementationofotherwiseeconomicallyrobustprojects.Developingcountriesoftenarguethatthetotalvolumeofaparticularpollutantemittedeitheronacountrywideorregionalbasisisfarlowerthaninthedevelopedcountriesandthatstringentstandardsshouldbeappliedonlywhenthetotalvolumeofaparticularpollutantemittedfromallsourceswillresultinambientconcentrationsexceedingpermissiblelevels.

Ineffect,thesecountriesarearguingfortheadoptionofecologicallybasedemissionstandardsforindustrialplants.Establishingecologicallybasedemissionstandardspresupposesacceptanceoftheconceptofcriticalpollutantloadsbycalculatingtheseloadsforeachcountry.Forlarge

pollutantloadsbycalculatingtheseloadsforeachcountry.Forlargecountries,criticalpollutantloadsmighthavetobecalculatedonanarea-by-areabasis.Thisimpliesthatdevelopingcountriescouldadoptlessstringentstandardsthanindustrializedcountriesunlessepidemiologicaldataindicatedthataparticularpollutantwasalreadycausinghealthproblems.Thisconceptmustbeappliedwithcaution,however.Ifacountryisindustrializingrapidly,morestringentstandardsmustbeadoptedinanticipationofhigheremissions.

Pursuingeconomicdevelopmentwithoutregardtoitsenvironmentalconsequencesisunacceptable.Itislesscostlytomakeincrementalinvestmentsinstate-of-the-arttechnologynowtocontrolpollutionthantomakefurtherinvestmentslater,if

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thoseinvestmentsarelikelytobeneededinthenot-too-distantfuture.However,thecostsoftheseinvestmentsmustbereasonable,andthelikelyimpactofthisspendingonothersectorsmustbetakenintoaccount.Medicalfacilitiesandservices,food,education,transportation,andothersocialservicesneedtobeprovidedaswellascleanair.Abalancemustbestruckbetweenwhatisdesirableandwhatisachievable.Crucialtothedevelopmentandimplementationofanyprojectistheabilitytofinanceit.Financingisunlikelytobeavailablefrominternationalagenciesunlessenvironmentalmitigationmeasuresarebuiltintotheproject.Environmentalimpactassessments,whicharenowaprerequisiteforWorldBankprojectappraisal,ensurethatnecessarycontrolmeasureswillbeincludedinprojects.

Technology-andpolicy-basedoptionsneedtobeidentifiedearlyinthecycle.Discussionofthetechnologicaloptionswillbeintroductory,sinceadetailedreviewwouldrequiretheidentificationofalltheavailabletechnologies,thefactorsthatmustbetakenintoaccountintheestimationofcapitalrequirements,andadiscussionoftheproblemsofcost-benefitanalysis.

Whenthecostsofinvestinginairpollutionprogramsarehighandsuchinvestmentscoulddivertresourcesfromotherusefulandpopularprograms,investmentsthatcanbejustifiedineconomicandfinancialtermsunderstoodbypolicymakersaremorelikelytowinapproval.Inthedevelopingcountriesthequestionthatmustbeansweredbypolicymakersandinternationalagenciesisnotwhetheraprogramhasmeritbutwhetheritiscrucialforhumanwelfare.Suchproblemsaschildmalnutrition,polluteddrinkingwater,andhighlevelsofunemploymentwillordinarilytakeprecedenceoverprogramstocombatairpollution.Nevertheless,thebenefitsofairqualityenhancementareveryreal.Aswillbeshowninthisreport,theycanbemeasuredandshouldthereforereceivehighpriority.

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2HealthandEnvironmentalEffectsofMajorPollutants,PartI:CarbonMonoxide,Hydrocarbons,OxidesofNitrogen,SuspendedParticulateMatter,andLeadThischapterandtheonethatfollowsdiscussthepotentialhealthandenvironmentaleffectsofmajorairpollutants.Theseeffectsarediscussedtodemonstratetheneedfortheirreduction,particularlyinhigh-population-densityareasandmajorcities.Thefindingsfromseveralstudies,mainlyfromtheindustrializedcountries,arepresented,inasmuchasverylittlemeaningfulinvestigativeworkhasbeendoneonairpollutioninthedevelopingcountries.Nonetheless,thelessonsofthestudiesarehighlyrelevanttodevelopingcountries,especiallybecausetheyarenowpassingthroughsomeofthesamestagesofgrowththattheindustrialcountrieshavetraversedpreviously.

CarbonMonoxide

Effects

Inhalationofcarbonmonoxide(CO)byhumanbeingshasdetrimentaleffectsonhealth.TheamountofharmdependsontheconcentrationofCOandthedurationofexposureandiscausedbythespecialaffinityofhemoglobininthebloodforcarbonmonoxideabout240timesthatofitsaffinityforoxygen(Romieu1992).Carbonmonoxideformsastrongcoordinatebondwiththeironatomoftheprotohaemcomplexinhemoglobintoproducecarboxyhemoglobin(COHb).COHb,inturn,reducestheamountofavailableoxygenneededinthebloodtocarryoutnormalbodilyactivities.Hence,morebloodneedstobepumpedtodeliverthesameamountofoxygen,resultingin

strainontheheart.COHblevelsofapproximately1.2to1.5percentarefoundinanormalpopulation.Intraffic-congestedareas,however,elevatedconcentrationsofCO(20to30mg/m3,or17to26ppm)arefoundintheambientair,andthiscanleadtoequilibriumCOHbbloodlevelsof3percent,comparabletothe3to4percentCOHbfoundincigarettesmokers(Romieu1992).Table2.1givestheexpectedlevelsofCOHbinthebloodatdifferentconcentrationsofCO.

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Table2.1PredictedCOHbBloodConcentrationsforSubjectsEngagedinDifferentTypesofWork

COconcentration PredictedCOHblevel(%)forthoseengagedinppm mg/m3 Exposuretime Sedentarywork Lightwork Heavywork100 115 15minutes 1.2 2.0 2.850 57 30minutes 1.1 1.9 2.625 29 1hour 1.1 1.7 2.210 11.5 8hours 1.5 1.7 1.7

Note:ppm=partspermillion;mg/m3=milligramspercubicmeterSource:Romieu(1992).

Ingeneral,thosewhoexerciseheavilyoutdoorsorworkoutdoorsaremorepronetosuffertheeffectsofelevatedCO.TheclassicsymptomsofCOpoisoningarerevealedatlevelsabove10percentCOHb.Betweenthelevelsof10and30percent,thesesymptomsareheadacheanddizziness.Atlevelsabove30percent,thesymptomsaresevereheadache,cardiovasculareffects,andmalaise.Thechancesofcomaanddeathareheightenedwhenthelevelexceeds40percent(Romieu1992).ThesefindingsseemtobeinaccordwiththesignsandsymptomsofCOHbshowninTable2.2(Watkins1991).Otherstudies,however,indicatethatdrowsiness,impairedperceptionandthought,andslowedreflexesoccuratlevelsof5to10percent(Adams1990).AccordingtoWatkins(1991),theconcentrationsinTable2.2aremuchhigherthanthoseusuallyexperiencedbyroadusersorothersexposedtovehicleexhaustfumes.However,otherstudiesindicatethatparkingattendantsandtrafficpoliceshowincreasedratesofchronicrespiratoryandcardiacdisorderslinkedtoCOexposure(Adams1990).ThereisnodoubtthatCOisfatalwheninhaledatveryhighconcentrations,andheartdiseasepatients,pregnantwomen,infants,seniorcitizens,andthoseespeciallysusceptibletorespiratoryproblemsmayexhibitsymptomsofCOpoisoningatlowerpercentagesofCOHbthanindicatedinTable2.2.Concentrationshigherthan9ppm,forexample,mayincreasetheprobabilityofanginaattacksfortheestimated5to7millionpeople,aprevalencerateof3percent,intheUnitedStateswhoareatrisk(Krupnik

prevalencerateof3percent,intheUnitedStateswhoareatrisk(Krupnik1991:13).

AlthoughstudieshavebeenconductedtodeterminethehealtheffectsofCOatvariousambientlevels,thedataneededtodeterminedose-responsefunctionsaccuratelyhavenotbeencollected.VariousempiricalequationshavebeenproposedrelatingconcentrationsofCOinambientairtotheformationofCOHblevelsinblood.Mostrelationshipsseemtobelinear,atleastinitially,andthenreachanequilibriumconcentrationofCOHbafterexposureoflongduration(seeFigure2.1).AccordingtotheWHO(1979:90),analyzingCOlevelsinairandCOHblevelsinbloodshouldnotberegardedasalternativemethodsofmonitoring,sinceitisnoteasytoestimatetherelationshipbetweentheCOlevelinambientairandCOHblevelinbloodbecausethe

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concentrationofCOanddurationofexposureareinfluencedbycomplexfactorsthatis,weatherconditions,trafficdensity,ageandstateofrepairofthevehiclefleet,thetypesofemissioncontrolequipmentandenforcement,highwaydesign,timeofday,andlevelofventilationwillallaffecttheconcentrationofambientCOatanyparticularlocationandthereforethecorrespondinglevelsofCOHb.Congestedstreetsandconfinedspacessuchastunnelsandparkinggarages(particularlythosewithinadequateventilation)arelikelysitesforhighconcentrationsofCO,whereaswidestreetswithfree-flowingtrafficareunlikelytohaveunsafeCOaccumulations.Dispersionfactorsmayalsoplayaroleindiscrepanciesinthedatagatheredatmonitoringstations.NumerousstudieshaveindicatedthatthelevelsofCOandotherairpollutantsinsidemotorvehiclesandalongroadsidesaretypicallyhigherthanthelevelsrecordedsimultaneouslyatfixed-sitemonitors.Thissuggeststhatpeopleinmotorvehiclesareatmostrisktoairpollutants,followedbypedestriansandstreetvendors,andthenbythegeneralurbanpopulation,sincelevelsofmotorvehiclepollutantsdeclinewithincreasingdistancefromroads(Flachsbart1992).

Table2.2SignsandSymptomsofIncreasingCOHbLevelsinanAverageAdultCOHb(%)

Signsandsymptoms

010 None1020 Tightnessacrosstheforehead,possibleslightheadache,dilationofthe

cutaneousbloodvessel2030 Headacheandthrobbinginthetemples3040 Severeheadache,weakness,dizziness,dimnessofvision,nausea,

vomitingandcollapse4050 Sameasabove,greaterpossibilityofcollapse,syncope(fainting)and

increasedpulseandrespiratoryrates5060 Syncope,increasedpulserate,coma,intermittentconvulsions,and

Cheyne-Stokesrespiration6070 Coma,intermittentconvulsions,depressedheartactionandrespiratory

rate,andpossibledeath7080 Weakpulse,slowrespiration,respiratoryfailureanddeathwithinafew

hours8090 Deathinlessthananhour90+ Deathwithinafewminutes

Source:Watkins(1991).

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Figure2.1UptakeofCObyBlood,aDose-ResponseCurve

Note:ThistypicalCOdose-responsecurvehasbeenderivedfromobservationsmadebyForbesandothers(1945).ActualCOHblevelinanyindividualmayvaryconsiderablyfromthatpredictedinthisfigure,

dependingonprevailingconditionsanddurationofexposure.Source:WHO(1979:91).

Typically,ambientCOstandardsareaveragedover8hours.Thisisbecauseittakesapproximately4to12hoursforCOHblevelstoreachequilibriumwithambientCOlevels(UNEPandWHO1988).TheUnitedStatesandWHOhavestringentCOstandards(9ppmor10mg/m3)foran8-hourperiod.Theseconcentrationsmayseemtoostringent,sincetheexpectedcorrespondingCOHblevel(basedonamodelbyCoburnandothers1965)appearstobeapproximately1.5percentforsubjectsatrestand1.7percentforthoseengagedinheavyphysicalwork(WHO1979:119),andaccordingtosomestudies

wouldhavenonoticeableeffectonthegeneralpopulation.Itshouldbeborneinmind,however,thattheseguidelinesaredesignednotonlytogivethegeneralpopulationanadequatemarginofsafetybutalsotoprotectthosewhoareparticularlysusceptible.AstudybytheGlobalEnvironmentalMonitoringSystem(GEMS),usingarelativelysmallsampleof20cities(predominantlyinindustrialcountries),foundthatapproximatelyhalfwereviolatingtheWHO8-hourguideline(UNEPandWHO1988).

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ManyurbancitiesindevelopingcountriesprobablyexceedtheWHOCOguidelineaswell,althoughthedataneededtoprovethisdonotexist.

Sources

PetroleumfuelsusedinmotorvehiclesarethelargestcontributorsofCOemissions(seeBox2.1).Forexample,between1940and1970theU.S.motorvehiclefleetincreasedrapidly.Carbonmonoxideemissionsduringthesameperiodrosefrom73milliontonstoapproximately100milliontons(WHO1979:23).ThisincreaseinCOemissionsinparallelwiththeincreaseinnumberofvehiclesmayhaveresultedprimarilyfromlackofstringentemissioncontrols.Evenwithemissioncontrolsinplace,thetransportsectorremainsthemajorsourceofCOemissionscausedbyanthropogenicactivities.Approximately90percentoftheCOintheurbanenvironmentsofmanycountriesisattributedtomobilesources(Romieu1992).COcanalsoaccumulateindoorsinacuteorfataldosesfromtheuseofcoal,gas,oroilforcookingorinheatingappliancesthataremaladjustedandinadequatelyventedtooutsideair.

Box2.1ChemicalNatureofCarbonMonoxide

Carbonmonoxide(CO)isacolorless,odorless,tastelessgasthatisslightlylessdensethanair.Incompletecombustionofcarbon-containingfuelsproducescarbonmonoxide,andtheprincipalsourceisemissionsfrommotorvehicles.Intheory,allthecarbonatomsinfuelareconvertedtocarbondioxide(CO2)ifenoughoxygenispresentintheair/fuelmixtureinthecarburetorofamotorvehicle:

Ifthefuelmixtureistoo''rich"thatis,containstoomuch

fuelandtoolittleairconsiderableamountsofCOwillbeformed:

Theoretically,theCOwillbeconvertedtoCO2intheatmosphere:

Butthisconversionisnormallyquiteslow,andCOcontinuestobeCOfor0.2to0.3yearsorfortwoorthreemonths.

Note:(l)=liquidphase;(g)=gasphase.

Source:Mastersonandothers(1985:534).

Table2.3summarizestheoutlookforworldwideCOemissionsfortheperiod1980to2005.Theseestimatesassumemoderateeconomicgrowthgloballyandrisingoilprices.Basedontheseestimates,totalworldwideCOemissionsareexpectedtobeonlyslightlyhigherin2005thantheywerein1980.The57percentprojecteddeclineinCOemissionsfromtheOECDtransportsectorfrom1980to2005istheprincipalfactorlimitingtheoverallincrease.ThetransportsectorwillremainthemajorsourceofCOemissions,however,especiallyintheOECDcountries.COemissionsinboththecentrallyplannedeconomies(CPEs)andthedevelopingcountriesarealsoontherise.As

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Table2.3SummaryofCOEmissionsOutlook,19802005Risingoilpricecase(103metrictonsofCOperyear)

Region 1980 1986 1995 2005OECDsummaryElectricitygeneration 1243(1%) 1346(1%) 1721(2%) 2136(1%)Industry 1170(1%) 1024(1%) 1000(1%) 1150(1%)Residential/commercial 13827(8%) 12317(9%) 9860(9%) 8487(11%)Transport 152427(90%) 127508(89%) 99198(88%) 64783(84%)Transformation 565(0%) 507(0%) 475(0%) 382(0%)Total 169232(100%)142702(100%) 112254(100%) 76938(100%)CPEsummaryElectricitygeneration 897(2%) 1042(2%) 1302(2%) 1863(2%)Industry 1247(3%) 1294(2%) 1484(2%) 1864(2%)Residential/Commercial 31944(64%) 31968(60%) 32104(51%) 33230(42%)Transport 15429(31%) 18622(35%) 27951(44%) 40960(52%)Transformation 92(0%) 350(1%) 452(1%) 658(1%)Total 49609(100%) 53276(100%) 63293(100%) 78575(100%)DevelopingcountrysummaryElectricitygeneration 203(0%) 332(0%) 568(0%) 1082(1%)Industry 341(0%) 424(0%) 562(0%) 769(0%)Residential/commercial 99711(68%) 86046(59%) 93468(53%) 96741(45%)Transport 46440(32%) 58589(40%) 80024(46%) 11571(54%)Transformation 111(0%) 165(0%) 273(0%) 400(0%)Total 146806(100%)145556(100%) 174895(100%) 21463(100%)WorldsummaryElectricitygeneral 2343(0%) 2720(1%) 3591(1%) 5081(1%)Industry 2748(1%) 2742(1%) 3045(1%) 3783(1%)Residential/commercial 145483(40%) 130331(38%) 135432(39%) 138458(37%)Transport 214296(59%) 204719(60%) 207173(59%) 220913(60%)Transformation 768(0%) 1022(0%) 1200(0%) 1439(0%)TOTAL 365648(100%)341534(100%) 350441(100%) 369674(100%)Note:Duetorounding,somepercentagesmaynotaddupto100.Source:OECD/IEA(1991:147-48).

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thevehicularpopulationsofCPEsanddevelopingcountriesincrease,theshareofworldCOemissionsfromOECDcountriesisexpectedtodeclinefromthe46percentof1980to21percentin2005,whilethedevelopingcountries'shareisexpectedtorisefrom40percentto58percentandtheCPEsharefrom14percentto21percent.Thesechangesareprimarilyattributabletodifferencesinemissioncontrolpoliciesinthethreegroups.SimilardifferencesaffectednationalemissionsofCOduringthe1970s.COemissionsfrommotorvehiclesroseinFinland,France,Sweden,andSwitzerlandintheearly1970s,andtheUnitedKingdomsawanincreaseinCOemissionsovertheentiredecade.Meanwhile,theUnitedStatesandCanadaevidencedadeclineinCOemissionsresultingfromtheearlycreationandenforcementofstringentemissionstandards(Holdgateandothers1982:520).

Inlinewiththeobservationthatdevelopmentneednotworsenenvironmentalquality,itisworthnotingthatanincreaseinvehicledensitydoesnotnecessarilyleadtoanincreaseinCOemissionswhenemissionstandardsandenforcementofemissioncontrolsareeffective.Astudydonein1980tomeasureCOconcentrationsinsidevehiclesonasuburbanhighwayinCaliforniafoundthataverageCOconcentrationswere51percenthigherthanwhenvehiclesonthehighwaywereresurveyedin1991bythesameresearchersusingasimilarmethodology.Theresearchersattributedthedeclinetothereplacementoftheoldervehiclefleetwithnewermodelshavingloweremissionfactors,anditwasparticularlysignificantthatthedeclinewassosubstantialeventhoughvehicledensityonthehighwayhadincreasedby17percentduringthesameperiod(Flachsbart1992).

Unfortunately,thevehicleturnoverrateindevelopingcountriesislow,andthevehiclesnowontheroadaregenerallyolderandhavenopollutioncontroldevices.Undersuchcircumstances,anincreaseinvehicledensityisboundtoincreasetheconcentrationofambientCO.

Sincevehicleinspectionandmaintenanceprogramsarenotwelldevelopedindevelopingcountries,itisalsomorelikelythatdangerousorevenlethalconcentrationsofCOmayaccumulateinsidemotorvehiclesbecauseoffracturesinexhaustsystemsorothermechanicaldefects.Furthermore,thestop-and-gotrafficthatisthenorminurbancentersindevelopingcountriesmayaggravateexposuretoCOemissions,whicharehighestwhenanengineidlesanddecreasewithincreasingenginespeed(seeBox2.2).

Hydrocarbons

ChemicalNatureandEffects

Hydrocarbons(HCs)areorganiccompoundsconsistingmainlyofcarbonandhydrogen.Straight-chaincompoundsareknownasaliphatics;thosewithacyclicstructureareknownasaromatics.Hydrocarbonsareprecursorstoozoneformation.Aromatics(particularlybenzene,whichimprovestheoctanevalueofgasoline)alsopromotetheformationofnitrogenoxides.Whenhydrocarbonsinteractwithnitrogenoxidesinthepresenceofsunlight,ozoneistheresult.Athighconcentrations(100to

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Box2.2TheTrafficPoliceofJaipur,India

Adarkzoneofblacksmokehangsabovetheground,acommonsightinJaipurCityduringthelateeveningandearlymorninghours.Thesmokehasbeenattributedtoanincreasingrateofvehicularpollution.ArandomcheckoftheambientairqualityofJaipurCitybytheDepartmentofEnvironmentinRajasthanrevealedthattheamountsoflead,carbonmonoxide(CO),sulfurdioxide(SO2),nitrogenoxides(NOx),andsuspendedparticulatematter(SPM)overa24-hourperiodwereabovethelimitsconsideredacceptablebytheWorldHealthOrganization.Itisestimatedthat90percentofthepollutioniscausedbyvehicularemissions.

Inordertoassesstheimpactofmotorvehicleemissionsonhumanbeings,astudywasconductedusingonehundredtrafficpoliceconstables.Theconstablesareexposedcontinuouslyforperiodsof6hoursormoretoemissionsfromvehiclesidlingatintersectionswithelevatedconcentrationsofCOandHC.SO2emissionsattheseintersectionsarealsosubstantial.

Thestudyrevealedthat94percentoftheconstablessufferedfromsomesortofphysicaldisorder.Eyeirritation,itchingskin,nasalcongestion,fatigue,coughs,lossofappetite,"burning"sensations,and"tenderness"intheabdomenwerecommoncomplaints.Respiratorydifficultiesanddigestiveproblemswerealsonumerous.Themoststartlingrevelationwasthehighincidence(55percent)oftuberculosisamongconstablesbetween20and30yearsold.

Whatmakesfindingsliketheseparticularlydisturbingis

thatthemajorityofIndia'surbanpoorlivebytheroadside,andtrafficintersectionsaretheplaygroundsofpoorchildren.

Source:Sinha(1993).

1,000timesthelevelsinambientair),hydrocarbonscauseminorirritationofmucosaandhaveageneralnarcoticeffect.BenzeneisclassifiedbytheU.S.EnvironmentalProtectionAgency(EPA)asahumancarcinogenbecauseofitslinktoadultleukemia.Concentrationsofbenzeneshouldbekepttomuchlessthan1ppm.Theothervolatilearomatichydrocarbonswithmethylsidechainsarenotconsideredtobecarcinogenicormutagenic.Formaldehydeisashort-termrespiratoryandskinirritantandmaybeacarcinogen.Individualvariabilityinsusceptibilitytotheharmfuleffectsofformaldehydeislarge,butmanypeopleinworksituationsshowsensitivitywhenexposedto500to3,000microgramsformaldehyde/m3.Thethresholdlevelisreportedtobeaslowas12micrograms.Astudyontheeffectsofformaldehydefoundthat120microgramsofformaldehyde/m3wasthethresholdlevelforhumanperceptionofitsodorandforirritationofeyes,nose,andthroat,whereas600microgramscausedlachrymation(tearing)and1,200microgramscausedrhinorrhoea(runnynose)anddrythroat(Suessandothers1985:97101).

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SourcesofHydrocarbons

Coalandpetroleumarethetwolargestorganicsourcesofaromaticcompounds.Petroleumisthemainsourceofbenzene,toluene,andxyleneusedinthechemicalindustryandintheproductionofhigh-octanegasoline.TheU.S.decisiontoeliminateleadedgasolinegraduallyatthebeginningofthe1980sandcompetitionforhigheroctanelevels(above91)resultedinaphenomenalincreaseinthelevelsofbenzeneandaromaticsingasolinebetween1979and1989.Figure2.2depictstheincrease.

Figure2.2TheDramaticRiseofAromaticsinU.S.GasolinePool,197989

Source:HyOx,Inc.,ofFallbrook,California,inOxy-FuelNews(1990).

Anywherefrom1to5percentofthecontentofmarketedgasolineconsistsofbenzene.Asgasolineismovedfromtherefinerytothemarketplace,benzeneisemittedintotheatmosphereatbulkgasolineterminals,depots,andservicestationsandfromtanktrucks.Itisalsoemittedwhengasolineispumpedintomotorvehicles(AlcoholOutlook1990).Thelargestsourceofatmosphericbenzene,however,ismotorvehicles.TheEPAstatesthat70.2percentofallbenzeneemissionscomefromvehicles.Ofthatfigure,70percentcomesfrom

motorvehicleexhaustpipesand14percentfromevaporation(Sinhaandothers1990).

Straight-chainoraliphatichydrocarbons,suchasaldehydes,areemittedbybothgasoline-anddiesel-fueledvehicles.Gasolineproducesfromabout0.6to2.3g/laldehydes,anddieseloil1to2g/l.Some50to70percentofallmotorvehicleemissionsareformaldehyde.Table2.4showsthecontributionoftheroadtransportsectortototalhydrocarbonemissionsin14cities.ExceptinOsakaandSeoul,theycontributedmorethan50percent.

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Table2.4ContributionofRoadTransportSectortoTotalHCEmissionsinSelectedCities

Region Year %HCMexicoCity 1987 89SãoPaulo 1981 83

1987 76Ankara 1980 73Manila 1987 82KualaLumpur 1987 95Seoul 1983 40Athens 1976 81aGothenburg 1980 89aLondon 1978 94LosAngeles 1976 61a

1982 50Munich 1974/75 96Osaka 1982 17Phoenix 1986 64aPercentsharesapplytoalltransport.Motorvehiclesaccountfor75to95percentofthetransportshare.Source:AdaptedfromWorldResourcesInstitute(1992:196).

OxidesofNitrogen

Effects

GenerallyexpressedasNOx,oxidesofnitrogenincludeNO(nitrogenoxide),N2O(nitrousoxide),andNO2(nitrogendioxide)(seeBox2.3).Nitrogenoxidesintheatmospherereducevisibility,helptoformacidaerosols,contributetoglobalwarming,andactascatalystsinthedecompositionofozoneintheupperatmosphere.Nitrogenoxidesalsocanformozonethroughinteractionwithhydrocarbonsinthepresenceofsunlight.Nitrogendioxideisarespiratoryirritantthatalsocausesirreversiblelungdamagetopersonsexposedtoitforlongperiodsof

time.Otherilleffectsincludechesttightness,burningoftheeyes,andheadaches.Peoplewithasthmaareparticularlyvulnerabletotheseeffectsandtobronchitis.RecurrentexposuretohighconcentrationsofNO2ismoredamagingthanconstantexposuretolower-levelconcentrations.

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Box2.3ChemicalNatureofNitrogenOxides

Oxidesofnitrogenareproducedduringtheburningoffuelsinaninternalcombustionengine.Nitrogenoxideiscreatedfirst;itthencombineswithmoreoxygentoformnitrogendioxide.Noticeableamountsofnitrogenoxideareproducedbythefollowingreaction:

Inurbanair,NOisconvertedtoNO2:

OxidesofnitrogenoftencontributetothegenerationofacidrainthereactionofNO2withwatervaporinairformsnitricacid(HNO3):

AcidrainfallinthewesternUnitedStatesisattributedmainlytonitricacid.

Note:(g)=gasphase;(l)=liquidphase;(aq)=aqueousphase.

Source:Mastersonandothers(1985:515-46).

Sources

Bacterialactioninthesoil,volcaniceruptions,andlightningarethemajorsourcesofatmosphericNOx.Althoughsuchnaturalphenomenageneratemuchlargeramountsofoxidesofnitrogenthananthropogenicsources,naturalemissionsofNOxarenotsignificantintermsofharmtotheenvironmentbecausetheycomefromsourcesallovertheglobeandgenerallyproducenegligibleconcentrationsinthe

air.Therelativelyminorroleofnaturalsourcescanbeseeninthefactthatnaturalconcentrationsofnitrogendioxideabovelandareasrangefrom0.4to9.4microgramspercubicmeter,whereasaverageannualmeanconcentrationsinurbanareasworldwidearesome20to90microgramspercubicmeter(WorldBank1988:218).

Theprincipalsourceofnitrogenoxidecreatedbyhumanactivityistheinternalcombustionengine,althoughthecombustionoffossilfuelsinhomesisalsoasource.Oxidesofnitrogenalsoareemittedbyplantsmanufacturingexplosives,fertilizer,andglass;inironorepreparationplants(sinteringandpelletizing);andatpetroleumrefineriesandelectricpowerstationsthatburnfossilfuels.

Table2.5summarizesexpectedNOxemissionsintheworldfortheperiod1980to2005.ThetransportsectorwillcontributethemajorshareofNOxemissions,withgenerationofelectricityaclosesecond.InbothdevelopingandOECDcountriesthetransportsectorcontributesthelargestshareofNOxemissions,whereasthegenerationofelectricityyieldsthemostNOxemissionsinCPEs.Itisestimatedthatwhereastransport-relatedNOxemissionsfromOECDcountrieswilldeclinefrom63percentto40percent,thedevelopingcountries'sharewillincreasefrom19percentto35percentandtheCPEs'sharewillrisefrom18percentto24percentoverthisperiod.

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Table2.5SummaryofNOxEmissionsOutlook,19802005BilliongramsofNOx

Region 1980 1986 1995 2005OECDsummaryTransport 20352(50%) 19828(52%) 19366(54%) 18244(52%)Residential/commercial 2082(5%) 1977(5%) 1915(5%) 1891(5%)Industry 5304(13%) 4040(11%) 3545(10%) 3288(9%)Electricitygeneration 11566(28%) 10623(28%) 9994(28%) 10617(30%)Othertransformation 1706(4%) 1415(4%) 1063(3%) 782(2%)

Total 41010(100%) 37883(100%) 35883(100%) 34822(100%)CPEsummaryTransport 5644(24%) 6231(24%) 8959(27%) 11056(25%)Residential/commercial 2666(11%) 2920(11%) 3308(10%) 3774(9%)Industry 4606(20%) 4726(18%) 5347(16%) 6794(15%)Electricitygeneration 9790(42%) 11023(42%) 13615(41%) 19381(44%)Othertransformation 561(4%) 1593(6%) 2130(6%) 3314(7%)

Total 23267(100%) 26493(100%) 33359(100%) 44319(100%)DevelopingcountrysummaryTransport 6196(48%) 7750(48%) 11853(49%) 16075(45%)Residential/commercial 2236(17%) 2106(13%) 2615(11%) 3088(9%)Industry 1536(12%) 1766(11%) 2365(10%) 3194(9%)Electricitygeneration 2271(18%) 3633(23%) 6071(25%) 11455(32%)Othertransformation 644(5%) 852(5%) 1349(6%) 1948(5%)

Total 12883(100%) 16107(100%) 24253(100%) 35760(100%)WorldsummaryTransport 32192(42%) 33808(42%) 40178(43%) 45375(39%)Residential/commercial 6984(9%) 7003(9%) 7838(8%) 8753(8%)Industry 11446(15%) 10532(13%) 11257(12%) 13276(12%)Electricitygeneration 23626(31%) 25279(31%) 29679(32%) 41453(36%)Othertransformation 2910(4%) 3860(5%) 4542(5%) 6045(5%)

TOTAL 77158(100%) 80482(100%) 93494(100%) 114902(100%)Note:Duetorounding,somepercentagesmaynotaddupto100.Source:OECD/IEA(1991:149-50).

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Box2.4HarvardSixCitiesStudy

Studiestodeterminetheassociationbetweenairpollutionandmortalityrateshaveoftenbeencriticizedongroundsthattheinvestigatorsdidnotdirectlycontrolforotherfactors,suchastobaccosmoking.Theconsistentfindingsobtainedfromawell-characterizedcohortofadultsbytheHarvardSixCitiesStudysuggestthatthecriticismhaslimitedvalidityatbest.

DatafortheHarvardstudywereobtainedfrom8,111adultsinsixcitiesintheUnitedStates,commencingin1974andconcludingin1991.Theobjectofthestudywastodeterminetheeffectsofairpollutiononmortalitywhilecontrollingforseveralriskfactors,includingtobaccosmoking;sex;age;educationlevel;andoccupationalexposuretodust,gases,andfumes.Dataonambientconcentrationsoftotalsuspendedparticulatematter,sulfurdioxide,ozone,andsuspendedsulfateswereobtainedforeachcommunityfromacentrallylocatedairmonitoringstation.

Theinvestigatorsfoundthatairpollutionhadsignificanteffectsonmortalityrateswhentheycontrolledfortheabove-mentionedriskfactors.Astatisticallysignificantassociationwasfoundbetweenfineparticulateairpollutionanddeathsfromcardiopulmonarydisease,andlungcancer.Theinvestigatorsconcludedthattheirconsistentfindingsprovidedanadditionalreasontoreduceurbanairpollution.

ThefindingsofthestudytookonglobalsignificancewhentheGlobalEnvironmentalMonitoringSystemoftheUnitedNationsestimatedthat70percentofthe

world'surbanpopulationlivesincitieswherethelevelofsuspendedparticulatesexceedsWHOguidelines.

Source:Dockeryandothers(1993:175359,1807);andGEMS,WHO,andUNEP(1987:47).

SuspendedParticulateMatter

ChemicalNatureandEffects

Particulatematteristhenameforabroadarrayoffinelydividedsolidsorliquidsthatmaybedispersedintotheairbycombustionprocesses,industrialactivities,ornaturalevents.Thenatureoftheparticulatesvariesdependingontheirsource.Particulatescanrangeindiameterfromlessthan0.1micrometers(µm)to1,000µmorso.Particulatessmallerthan10µmarereferredtoassuspendedinhalableparticulates;particulates2.5µmorsmallerareknownasfineparticulates.

Suspendedparticulatesthatmeasure10micronsorlessremainintheatmospherelongerthanlargerparticlesandaresmallenoughtobeinhaleddeeplyintotherespiratorytract.Hence,particulatemattercancontributetorespiratoryillnesses,withthetoxiceffectdependentonthechemicalnatureoftheparticulateandongasesthatmaybeadsorbedonparticulatesurfacesorabsorbedwithinparticulates(seeBox2.4).Particulatesintheatmospherealsoreducevisibility.

Sources

Largerparticlescomeprimarilyfromsoilandothercrustalmaterials,whereasfineparticulatescanbecombinationsofsoot,acidcondensates,andsulfateandnitrate

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particles.Respirableparticlesinurbanareasoftencontainlead,othermetals,organiccompounds,sulfuricacid,andothersulfates.However,thereisnosharpdividinglinebetweensmallerandlargerparticulates,sinceeventhelargerparticulatescanbefoundintheairundercertainconditions.

Naturalsourcesofparticulatematterincludevolcanicactivity,duststorms,forestfires,strongwindsblowingoverdrysoil,andpollenfromtreesandflowers.Combustionoffuelsforheatingandpowergenerationinindustrialprocessesandforpoweringmotorvehiclesalsogeneratesparticulates.Particulatescontainingleadcompoundsareemittedfromtheexhaustsofvehiclesthatuseleadedgasoline.Theblacksmokeofdieselvehiclesalsocancontainsubstantialamountsofparticulatematter;infact,uncontrolleddieselenginesemitsome30to70timesmoreparticulatematterthanvehiclesequippedwithcatalyticconvertersandusingunleadedgasolineasfuel(Sinhaandothers1990).

AstudyconductedbytheGEMSnetworkontheglobalspreadofparticulatepollutionovertheperiod198084foundthatparticulateemissionsin37of41citieseitherexceededorcameclosetoexceedingWHOguidelinesforparticulates(French1990:11).Nearly1.4billionurbanresidents,mostlyindevelopingcountries,maybeexposedtoairwithborderlineorunacceptableamountsofparticulates.Althoughtheselevelswerepartiallyattributedtonaturaldust,themainoffenderswerediesel-fueledvehicles,whichmaygenerate10timesmoreparticulatesthangasolineengines,andmotorscootersequippedwithtwo-cycleengines.AccordingtotheWHOandtheUnitedNationsEnvironmentProgramme,oneineveryfivepersonsintheworldisexposedtoexcessiveconcentrationsofparticulatematter.Table2.6liststenofthecitiesthatexceededtheWHOguidelineofanannualmeanof60to90µg/m3forparticulatematter.AnnualmeanconcentrationsofparticulatesinKuwait,New

Delhi,andBeijingexceededWHOguidelinesbyasmuchasfivetimes(French1990:1112).

Lead

Effects

Atpresentregulatoryagenciesandhealthorganizationshavenotreachedafirmconsensusonthemaximumpermissibleconcentrationofleadintheblood.Evenso,thegroupshaveallloweredtheamountofleadconsideredtocauseleadpoisoningasnewinformationabouttheneurologic,reproductive,andpossiblehypertensiveeffectsofleadtoxicityhasbecomeavailable.Currently,theWorldHealthOrganizationsuggeststhatalevelof20microgramsofmetalperdeciliterofblood(20µg/dl)isthemaximumacceptableconcentration.Otherstudiesconsiderthatthedetrimentaleffectsofexposuretoleadappearatconcentrationsofbetween10and15µg/dl(Correa1989:2).Itisnotnecessary,however,tohavebeenexposedtomajordosesofleadtocontractleadpoisoning.Thebodytendstoaccumulateleadoveralifetimeandcanreleaseitonlyslowly.Hence,evenexposuretosmallconcentrationsofleadoveralongperiodcan

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Table2.6SuspendedParticulateMatterinVariousCitiesBetween1980and1984City Annualmeana(µg/m3) Daysabovestandardb(peryear)

Kuwait 603 N/ANewDelhi 405 294Beijing 399 272Tehran 245 174Jakarta 231 173Bangkok 197 97KualaLumpur 130 37Zagreb 127 34RiodeJaneiro 114 11Lisbon 104 12Note:µg=1×10-6gm.aWHOannual-meanstandardis6090µg/m3.bWHOdailystandardis230µg/m3.Citiesareinviolationofthestandardwhentheyexceeditmorethansevendaysperyear.Source:French(1990).

produceharm.Itisthetotalbodyburdenofleadthatisrelatedtotheriskofadverseeffects(AgencyforToxicSubstancesandDiseaseRegistry1992:6).

Theprimarypathwaysofexposuretoleadareinhalationandingestion.Onceinhaledoringested,inorganicleaddoesnotundergobiologictransformation.Thisisincontrasttoorganiclead,whichentersthebodythroughinhalationorskincontactandisthenmetabolizedintheliver.Theprimarysourceoftheorganicformistetra-alkyl-leadadditivesingasoline.Irrespectiveofthemodeofexposure,however,thebiologicoutcomesarethesame:normalcellfunctionandanumberofotherphysiologicprocessesaredisrupted.Chieflyaffectedareperipheralandcentralnervoussystems,bloodcells,andthemetabolismofvitaminDandcalcium.

Lead'sdetrimentaleffectshavemoresevereconsequencesforchildrenthanforadults(seeBox2.5).Increasingmedicalevidenceshowsthatlead

thanforadults(seeBox2.5).Increasingmedicalevidenceshowsthatleadatrelativelylowlevelsinthebloodcanharmthementaldevelopmentofchildrenandthattheharmfuleffectspersistintoadulthood.Thedevelopingnervoussysteminchildrencanbeaffectedadverselyatblood-leadlevelsoflessthan10µg/dl(AgencyforToxicSubstancesandDiseaseRegistry1992:8).Neurologicdeficitsaswellasothereffectscausedbyleadpoisoningmaybeirreversible.Effectsonchildrengenerallyoccuratlowerconcentrationsthaninadults.Figure2.3showsblood-leadlevelsassociatedwithspecifichealtheffectsinchronicallyexposedchildrenandadults.

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Acuteexposuretoleadcanhaveharshoutcomes,insomecasesendingindeath.Severetoxicityisoftenassociatedwithblood-leadlevelsof70µg/dlorhigherinchildrenand100µg/dlorhigherinadults(AgencyforToxicSubstancesandDiseaseRegistry1992:12).Atlevelsof80µg/dl,poisoningofthecentralnervoussystemcanoccur,causingconvulsions,coma,anddeep,irreversiblementalretardation.Functionalchangesintheperipheralnervoussystemandanemiacanalsooccuratthatlevel.Alaginthetransmissionofnervesignalsfromthebraintotherestofthebodyhasbeenobservedatlevelsbelow40µg/dl(Correa1989:2).

Otherscientificstudieshavedemonstratedthatleadisalsolinkedtohighbloodpressureandmaysignificantlyincreasetherisksofheartattacksandstrokesinadults.Leadalsocausesreproductivetoxicity.Maternalleadstorescaneasilybetransmittedtothefetusthroughtheplacenta,therebyplacingthefetusatgreatriskofsufferingreductionsingestationalage,birthweight,andmentaldevelopment(Romieu1992).

Ithasbeendeterminedthatthelevelsofleadingasolinearecorrelatedwithlevelsinthebloodstreamofthepopulation.Between1972and1984theconsumptionofleadadditivesingasolinedeclinedandwasfollowedbyadecreaseinleadconcentrationsinambientair.Thischange,inturn,hadstrikingeffectsontheblood-leadlevelsoftheU.S.population(Shy1990).Figure2.4depictsthecorrelation:aparalleldecreaseinblood-leadlevelsasthequantityofleadusedingasolinedecreased.Thepresentaverageblood-leadconcentrationintheU.S.populationisbelow10µg/dl;itaveraged16µg/dlbeforethelegislatedremovalofleadfromgasoline(AgencyforToxicSubstancesandDiseaseRegistry1992:14).Figure2.5givesblood-leadlevelsofpersonsincitiesinseveralcountries.Peopleincountriesthatstilluseleadedgasoline,onaverage,havehigherleadcontentintheirblood.

Sources

Metalsmelters,batterymanufacturingplants,andleadedgasolinearetheleadingsourcesofairbornelead.Althoughthedetrimentaleffectsofleadonhumanhealthhadbeenknownforalongtime,itwasnotwidelyrealizedthatgasolinewasamajorsourceofleadintheairuntilthemid-1970s.Althoughleadingasolineaccountsforonlyabout10percentofallrefinedleadproducts,itisnowunderstoodtoaccountfor60percentofanthropogenicleademissions(possibly90percentincitieswithhightrafficcongestionandvehicleswithoutadequateemissioncontrolsystems).

Gasolineisnowconsideredbyfarthegreatestcontributortoairborneleadintheindustrializedworld(GEMS,UNEP,andWHO1988).Nearlyalltheleadaddedtogasolineisreleasedtotheatmosphereatsomepoint.Theorganicformstetra-ethyl-lead(TEL)ortetra-methyl-lead(TML)arereleasedintotheair,principallyasinorganicleadsaltsandoxidesinaerosolform.Only1percentoftheleadingasolineisemittedunchangedasTELorTML.Leadparticlesremainsuspendedinairforlongdurationsbeforesettling.Theymayalsobedepositedinthesoilandcontaminatefoodandwater.Thus,leadcanbeinhaledfrommotorvehicleemissionsoringestedthroughfoodandwater.

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Figure2.3EffectsofInorganicLeadonChildrenand

AdultsLowestObservableAdverseEffectLevelsSource:AgencyforToxicSubstancesandDiseaseRegistry(1992).

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Figure2.4CorrelationBetweenLevelsofLeadinGasolineandin

BloodstreamSource:Shy(1990).

Figure2.5

LeadPollutioninSelectedCitiesSource:UNESCAP(1992).

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Box2.5TheEffectsofLead

About10percentoftheleaddischargedbymotorvehiclesisdepositedwithin100meters(0.6miles)ofroadsidesareasfrequentlyoccupiedbychildrenatplayindevelopingcountries.Onlyafewstudieshavebeenconductedindevelopingcountriesontheeffectsofleadonchildren'shealth,however.Thesestudies,conductedbytheWHO,revealthatchildrenindevelopingcountrieshaveabody-leadcontentthreetimesthatfoundinchildrenintheUnitedStates,Japan,orWesternEurope.Althoughthereisincreasingevidenceoflead'sharm,amajorityofthedevelopingcountriescontinuetouseleadedgasoline.

AstudyconductedinmetropolitanManila(JimenezandValasquez1989:55)foundconcentrationsofleadinbloodsamplesfrom544infantsandchildrenbetweentheagesof4monthsand14yearstobesufficienttowarrantconcern.Theaverageleadlevelinthesampledpopulationwas22.8µg/dl,withapproximately8percentofthechildrenhavinglevelsgreaterthan30µg/dl.Theselevelsareconsideredtobehighenoughtohavedetrimentaleffectsonthechildren(seeFigure2.3).Thestudyalsofoundasignificantcorrelationbetweenhighleadlevelsinthebloodandproximityofthehouseholdtodensetraffic.

Thenegativeeffectsofleadareenduring.Astudythatmeasuredtotalbody-leadburdeninprimaryschoolchildrenwithhightooth-leadlevelsbutwithnoknownhistoryofleadpoisoningfoundthatthechildrenhadlowintelligencescoresandattentionspans,poorspeechand

languageskills,andpoorclassroomperformancecomparedwithchildrenhavinglowerconcentrationsoflead.Afollow-upreportonchildrenwithelevatedlevelsofleadintheirteethfoundasevenfoldincreaseinfailuretograduatefromhighschool,greaterabsenteeism,morereadingdisabilities,anddeficitsinvocabulary,finemotorskills,reactiontime,andhand-eyecoordination11yearslater.Theseobservedeffectsarebelievedtohavebeenasignoftheenduringtoxicityofleadratherthanofexcessiveacuteexposure,sincetheblood-leadlevelsoftheyoungadultswerelessthan10µg/dl(AgencyforToxicSubstancesandDiseaseRegistry1992:9).

Anotherstudy(Satterthwaite1993:93)conductedbetween1979and1981andinvolvingadultvolunteersin10citiesaroundtheworldrevealedthattheblood-leadlevelsofMexicoCityresidentswerethehighestandexceededWHOguidelines.Furthermore,theblood-leadlevelsweretwotofourtimesthoseofresidentsofcitieswherelow-leadandunleadedgasolinewereused.Sincematernalleadstoresreadilycrossthroughtheplacenta(AgencyforToxicSubstancesandDiseaseRegistry1992:2),itisnotsurprisingthata1988studyrevealedthatmorethan25percentofnewborninfantsinMexicoCityhadblood-leadlevelshighenoughtoimpairneurologicalandmotor-physicaldevelopment(Satterthwaite1993:93).

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3HealthandEnvironmentalEffectsofMajorPollutants,PartII:GreenhouseGases,SulfurOxides/AcidRain,Ozone,andChlorofluorocarbonsTwenty-fiveyearsagoitwasthoughtthatairpollutionwasaproblemonlyinpopulouscitiesoftheindustrializedregions.Itisclear,however,thatairpollutionisnowamajorprobleminurbanareasofthedevelopingworldaswell.Thischapterlooksbrieflyatsomeregionalandglobalairpollutionproblemsthegreenhouseeffect,depletionoftheozonelayerintheupperatmosphere,andacidrainthathavereceivedincreasingattentionsince1970.

CarbonDioxideandtheGreenhouseEffect

Theaccretionintheatmosphereofcarbondioxide(CO2),nitrousoxide(N2O),methane(CH4),ground-levelozone(O3),andchlorofluorocarbons(CFCs)hasledtoglobalwarming.Thesegasesabsorbinfraredradiation(IR)fromtheearth,ineffectactingasaninsulatingblanketpreventingheatfromescapingtheearth'satmosphere,causinga''greenhouseeffect."Approximately50percentofglobalwarmingisattributedtoCO2.CFCsareresponsibleforabout20percent,methaneforabout16percent,andground-levelozoneforabout8percent;nitrousoxideaccountsformostoftheremaining6percent(Tétrault1992:48).CFCs,CH4,O3,andN2OabsorbinfraredradiationmoreeffectivelythanCO2,andcollectivelytheirheat-trappingabilitymayequalthatofCO2.

Areportpreparedbyagroupof200scientistsfrommorethan24countriesknownastheIntergovernmentalPanelonClimateChange(IPCC)concludedthatcontinuedproductionofCO2andother

greenhousegasesatcurrentlevelswouldcauseadoublingoftheirpreindustrialconcentrationsby2050.Thepanelalsoconcludedthattheaverageplanetarytemperaturewouldriseby3°Cbytheendofthetwenty-firstcentury,andtheearth'ssurfacetemperaturewouldthenbeapproximately18°C(64°F);thecurrentmeanglobaltemperatureattheearth'ssurfaceisabout15°C(59°F).Thismaybecontrastedtoanormforglobaltemperaturechangesof1to2°Coveraspanof1,000to10,000years,anditmaybesignificantthatittookariseofa"mere"5°Ctobringtheearthoutofthelasticeage(Tétrault1992:48).Hence,thecurrentrateofchangeintheearth'stemperaturemaywellbecauseforalarm.

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Table3.1summarizestheincreaseingreenhousegases.Acenturyago,theCO2concentrationintheatmospherewaslessthan300,000ppb(300ppm).Thecurrentconcentrationis354,000ppb(354ppm)andisexpectedtodoubleearlyinthetwentyfirstcentury(GraedelandCrutzen1990).AccordingtoSilver(1993:314)atmosphericCO2hasincreasedby25percentsincethebeginningoftheindustrialrevolution,morethan200yearsago.

Givenacontinuationofthecurrentrateofincreaseof0.4percentperyear,CO2couldhavesignificantadverseimpactsontheworld'sclimate.Theseeffectsmightincludeshiftsinclimaticzones,changesinrainfallpatterns,moreextremeweatherconditions,andariseinsealevel.Suchchangeswouldseriouslyaffectlifeinmostcountries.Ifglobalwarmingincreasesuncheckedthepolaricecapsmayshrink,causingtheoceanleveltoriseby5or6meters.Mostcoastalcitiesworldwidecouldbeaffected.Itisalsocontendedthatever-largerconcentrationsofCO2willhaveadirecteffectonfarmsandforestseveniftheydonotelevateworldtemperatures.Plantswouldgrowatanacceleratedrate,buttheirqualitywouldbepoor.Plantlifewouldcontainfewernutrients,andplantswouldharborincreasednumbersofinsects,whichwouldconsumemoreleaves.Ultimately,plantswoulddecomposemoreslowly,anditwouldtakelongerfortheirnutrientstoberestoredtothesoil(EnvironmentalUpdate1990).

Deforestationandthecombustionofcoal,oil,andnaturalgasinjectbillionsoftonsofcarbonintotheatmosphereeachyearandareresponsiblefortheincreaseinCO2.Fossilfuelstodaygenerateapproximately20billiontonsofCO2annually,andincreasesinvehicleusesuggestthatwithoutstrictemissioncontrolsCO2emissionswillcontinuetogrow.Between300and400poundsofCO2aregeneratedduringcombustionofthecontentsofasinglestandard(16gallon)tankofgasoline.Ithasbeenestimatedthatmotorvehiclesemitalmost15percentoftheworld'sCO2emissions(DeLuchiand

others1988).In1986,themobilesector,withapproximately25percentoftotalCO2emissionsintheOECDcountries,wasthesecondlargestcontributortoCO2emissions.Thissectorisexpectedtoaccountfor26percentinOECDcountriesin2005(OECD/IEA1991:48).Landclearing,cultivationofricepaddies,livestockproduction,andincreaseduseoffertilizers(Tétrault1992)alsocontributetoglobalwarmingbycausingtheaccumulationofmethaneandnitrousoxide.

Themostrecentavailabledataarefrom1989(WorldResourcesInstitute1992:208)andindicatethattheUnitedStatesandtheformerSovietUnion(FSU)arecurrentlythelargestandsecondlargestemitters,at18percentand14percent,respectively,ofgreenhousegases.TheEuropeanCommunityranksthird,at11percent.Indescendingorderbycountry,thelargestgreenhousegasemittersaretheUnitedStates(17.8to18.4percent),FSU(13.5to13.6percent),China(8.4to9.1percent),Japan(4.7to5.6percent),India(3.5to4.1percent),andBrazil(3.8to3.9percent).Together,thesecountriesaccountformorethan50percentofcurrentemissions.Itisworthnotingthatthreeofthesecontributorsaredevelopingcountries.

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Table3.1IncreaseinGreenhouseGasesConcentrationinatmosphere(ppb)

Gas

Majoranthropogenic

sources

Totalannualanthropogenic

emissions(millionsoftons)

Averageresidenceinatmosphere(years)

Average100yearsago

Current(approx.)

Projectedinyear2030

CO2 Fossilfuelcombustion,deforestation

5,500/~5,500

100 290,000 350,000 400,000to

550,000CH4 Ricefields,cattle,

landfills,fossil-fuelcombustion

300to400/550 10 900 1,700 2,200to2,500

N2ONitrogenousfertilizers,deforestation,biomassburning

6/25 170 285 310 330to350

CFCsAerosolsprays,refrigerants,foams

~1/1 60to100 0 About3(chlorineatoms)

2.4to6(chlorineatoms)

Note:ppb=partsperbillion;CO2=carbondioxide;CH4=methane;N2O=nitrousoxide;CFCs=chlorofluorocarbons.Source:AdaptedfromGraedelandCrutzen(1990).

Asdevelopingcountriesindustrialize,theiremissionswillrisesteeplyandmaycompoundenvironmentalproblemsunlessthesecountriesactinconcertwithorfollowtheleadofindustrializedcountriesinlimitingemissions.

SulfurOxidesandAcidRain

SourcesofSulfurOxides

Thelargestshareofsulfuremissionsfromhumanactivitiestakestheformofsulfurdioxide(SO2)andcomesfromtheburningofcoalandpetroleumproducts,petroleumrefining,andnonferroussmelting(seeBox3.1fora

products,petroleumrefining,andnonferroussmelting(seeBox3.1forabriefexplanationofthechemicalmakeupandbehaviorofsulfuroxidesaspollutants).LargemetropolitanareaswithheavydailyenergyproductionandindustrialactivitytendtohavesubstantialSO2thataccumulateinthelocalatmosphereanddisperseonlyslowly.AstudywasconductedbyGEMS/Air(GEMS,UNEP,andWHO1988:1620)overtheperiod198084todeterminethelevelsofSO2intheambientairof54citiesworldwide.ThestudyfoundthatwhereashalfthecitieshadacceptableSO2levels,theotherhalfhadeithermarginal(20percent)orunacceptable(30percent)SO2levelswithreferencetoWHOannualaverageguidelinesof4060mg/m3.Datafromthe54-citystudywasextrapolatedtoincludeapopulationof1.8billion,andanapproximationofthetotalglobalurbanpopulationatriskforSO2wasobtained.Thisapproximationrevealedthatwhereas625millionpeopleliveinurbanareaswithaverageSO2levelsthatarewithinWHOannualguidelines,upto1.2billionurbanresidentsliveinareaswheretheairqualityforSO2is

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eithermarginal(550millionresidents)orunacceptable(625millionresidents).Furthermore,nearlyone-fifthoftheworld'spopulation(975million)areestimatedtoliveincitieswheretheshort-termWHOguidelinesof100150mg/m3limitfor98percentofdailyaveragesisexceededmorethan7daysayear.

Box3.1TheChemicalNatureofSulfurOxides

Sulfurdioxideisacolorlessgasthatcanbedetectedbytastebymostpeopleatconcentrationsintherangeof1,000to3,000microgramspercubicmeter(0.35to1.05ppm).Itspungent,asphyxiatingodorbecomesapparentatconcentrationsaboveabout10,000microgramspercubicmeteror3.5ppm.Mostfossilfuelscontainsulfurinfreeorcombinedform.Mostofthesulfurandsulfurderivativesreleasedtotheairaretheproductsofcombustionprocesses.Sulfurcompoundsreactwiththeoxygenpresentinairtoformoxidesofsulfur,whichareprecursorstoacidrain.Muchofthesulfurdioxidepresentinairisconvertedtosulfurtrioxide:

Sulfurdioxideandsulfurtrioxidereactwiththewatervaporinairtoformdilutesulfurous(H2SO3)andsulfuric(H2SO4)acids:

Thesediluteacidsareformedhighintheatmosphereandmaybecarriedbyprevailingwindsasfaras1,000milesbeforefallingtoearthasacidrain.Sulfurpollutantscanalterawholeecosystemwhentheyfalltoearthasacid

rain.

Note:(g)=gasphase;(aq)=aqueousphase.

Source:Mastersonandothers(1985:515-46).

Table3.2providesdataonSO2concentrationsinselectedcitiesintheGlobalEnvironmentMonitoringSystems(GEMS)network(UNEP1991).Thedataarebasedontheannualmeanconcentrationsfortwoyears,withthetotalnumberofobservationsduringeachtwo-yearperiodshowninparentheses.Althoughmanymonitoringstationsmadedailyobservations,somemadethemlessfrequently(e.g.,onceeverysixdays),andthusthedatavaryincompletenessandmustbeinterpretedwithsomecaution.

Mostofthecitiesshowedagradualameliorationinairquality.Severaldevelopingcountries,however,reportedaworseningtrend.Ironically,concentrationsofSO2incitiesinlow-incomecountriesinthelate1970swere,onaverage,lessthanthoseincitiesofhigh-incomecountries.The1980s,sawareversal,however,asSO2concentrationsdeclinedincitiesofmiddle-andhigh-incomecountriesbutroseinthecitiesoflow-incomecountries(WorldBank1992:53).Thisshiftmayhavebeentheresultofthewealthiercountries'adoptionofmorestringentregulationofthesulfur

Table3.2ConcentrationsofSO2atSelectedGEMS/AirSites,198089(mg/mAnnualmeanconcentration(numberofobservations)

Country City Site 198081 198283 198485 198687 198889U.S. NewYork SR

CCRCCI

40.0(728)70.5(725)50.5(726)

35.0(716)64.6(730)47.0(723)

31.0(725)61.0(724)45.0(729)

27.0(361)a52.0(364)a40.0(350)

Brazil SãoPaulo CCRCCM

120.0(729)127.0(723)

97.0(728)99.0(723)

62.0(727)60.0(725)

54.5(120)73.0(120)

55.0(61)50.0(61)

China Beijing SICCCSRCCR

38.0(104)a66.0(113)a6.0(93)a98.0(110)a

60.5(365)101.5(374)15.0(349)147.0(368)

79.0(76)a130.0(86)a27.0(80)a161.0(78)a

61.5(297)112.5(326)28.5(324)125.0(293)

53.5(336)103.0(351)29.5(326)114.5(330)

Guangzhou SRCCRCCCCCI

38.0(104)a66.0(113)a117.0(76)a12.0(55)a

60.5(365)101.5(374)93.5(349)14.5(333)

79.0(76)a130.0(86)a67.5(336)113.0(317)

61.5(297)112.5(326)59.5(345)122.0(333)

53.5(336)103.0(351)58.5(353)135.5(354)

Shanghai CCICCRCCC

23.0(88)a52.0(87)a65.0(85)a

52.5(341)69.0(354)57.5(355)

49.0(86)a84.5(353)51.0(358)

40.5(357)98.0(351)77.5(358)

55.5(338)104.0(294)69.0(343)

Shenyang CCRCCICCCSI

29.0(73)a136.0(72)a72.0(72)a27.0(72)a

130.5(288)238.5(288)130.5(288)46.0(287)

135.0(288)320.0(288)58.0(72)a17.0(72)a

115.5(290)223.0(288)134.0(288)49.0(288)

70.0(288)207.5(288)101.5(288)29.0(276)

Xian SRCCRCCCSI

22.0(98)a108.0(119)a160.0(120)a46.0(117)a

30.0(383)118.0(396)104.5(397)66.5(394)

29.5(313)100.5(324)120.5(323)52.0(321)

31.0(276)118.0(289)92.5(288)66.5(287)

37.0(252)97.5(288)95.5(286)79.5(288)

Iran Tehran CCCSISR

169.5(172)137.5(154)140.0(160)

145.5(122)161.5(135)111.0(125)

97.5(115)87.5(94)47.5(98)

90.0(49)120.5(31)45.5(33)

211.0(42)149.0(28)81.5(30)

Japan Tokyo CCCSRCCI

42.0(719)40.0(722)48.5(724)

25.5(719)37.0(726)31.0(724)

24.0(731)31.0(727)31.0(731)

20.5(730)21.5(729)29.5(730)

19.0(360)18.0(366)26.0(366)

Thailand Bangkok SR 14.0(155) 18.0(310) 14.0(166) 14.5(1210) 13.0(190)Poland CCC 39.0(577) 40.5(583) 62.5(565) 35.0(488) 53.0(564)

Poland CCCCCICCR

39.0(577)27.5(583)31.5(558)

40.5(583)34.5(563)31.0(527)

62.5(565)48.5(547)44.0(522)

35.0(488)26.0(445)32.0(446)

53.0(564)34.5(542)40.0(506)

Spain Madrid CCCSRCCI

111.5(578)46.0(653)113.5(310)

80.5(566)33.5(654)91.0(208)a

47.5(499)27.5(582)

50.5(667)25.5(680)

31.5(663)17.5(658)

Yugoslavia Zagreb CCCSRCCI

87.5(671)41.5(730)41.5(731)

85.0(716)42.5(712)53.0(705)

104.5(727)64.5(694)75.0(721)

110.0(703)63.0(725)73.0(679)

82.5(694)44.0(637)102.0(698)

Note:=notavailable.;CCC=citycentercommercial;CCI=citycenterindustrial;CCM=citycentermobile;CCR=citycenterresidential;SI=suburbanindustrial;SR=suburbanresidential.aBasedononeyearofmeasurementonly.Source:AdaptedfromUNEP(1991).

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contentinfuels(seechapter4),conservation-basedenergypolicies,andashiftfromoiltosulfur-freeenergysourcessuchasnaturalgasandnuclearenergy(OECD/IEA1991).ItisalsopossiblethatthebuildingoftallersmokestacksindevelopedcountrieshassimplydispersedSO2emissionsfurtherafield.

Untilrecently,acidrainwasfoundonlyinthenorthernhemisphere.Butasdevelopingcountrieshaveexpandedtheirindustrialbasesandusedmorefossilfuel,acidrainhasalsoappeared.RecentdatashowthreateninglevelsofsoilacidityinpartsofBrazil,Colombia,Venezuela,India,SoutheastAsia,Japan,andChina.SoilsthathavebecomeacidicfromlandclearingandbiomassburninghavealsobeendetectedeveninpartsofunindustrializedAfrica(Tétrault1992).

EffectsofSO2andAcidRain

Anestimated1billionormorepeopleworldwideareexposedtounhealthylevelsofatmosphericSO2(WorldBank1992:53).Clinicalstudiesusinghumansubjectshavefoundthatchildrenandbothhealthyandat-riskadultsarevulnerabletoSO2emissions,dependingonhealthstatus,individualsensitivity,andactivitylevel.Individualswhosufferfromchronicrespiratorydiseasessuchasbronchitis,emphysema,andasthmamayexperiencecoughinganddifficultiesinbreathingwhentheSO2concentrationrisesfrom0.1to0.2ppm.Ithasbeendocumentedthatasthmaticsareupto20timesmoresensitivetoatmosphericSO2thanhealthyadults(U.S.Congress1987).AcuterespiratorydiseasesareamajorprobleminbigcitiessuchasShanghai,wherehousingiscrampedandalackofzoningrestrictionsplaceslargenumbersofpeopleindwellingsadjacenttoindustrialplantsthatemithighlevelsofSO2.Thecity'sairqualityproblemsareattributedtoits91,000industrialboilersandtoitshouseholdstoves,whichburn25milliontonsofcoalayear.GEMShasrecordedSO2levelsinShanghaiatoraboveWHOguidelines,and

thelevelsmaywellbetwiceashighasrecommendedinareasnotmonitoredbyGEMS(UNEPandWHO1992:33).SO2pollutionisalsomeasurablyaffectingthehealthofarmyinducteesinPoland.ChronicbronchitiswasfoundtobethreetimesasprevalentininducteesatarmyrecruitmentcentersincitieswithelevatedconcentrationsofSO2thanatcentersincitieswithcleanerair(WorldResourcesInstitute1993:546).

SO2isaprimarycomponentofaciddepositionanddamagestheecosystembothdirectlyandindirectly.Thedirectharmisseeninfoliage,particularlycropplantssuchaswheat,barley,oats,whitepine,cotton,alfalfa,buckwheat,andsugarbeets,whichcanbeseverelyinjuredbySO2concentrationsofaslittleas0.3ppm.SO2alsodisruptsecosystemsindirectlythroughacidificationofsoilsandsurfacewaters.ThesynergisticeffectofSO2andlowlevelsofozoneornitrogenoxidescausessevereinjurytoplants.ThisisevidentinEurope,whereforestshavesuffereddramaticallysincethe1970s.Accordingtoarecentanalysis,about75percentofEurope'scommercialforestshavebeenaffectedbySO2.Thecostsofforestdiebackscanrangefromdecreasedrevenuesfromsmallertimberharvestsandsubsequentlossestowoodmanufacturingindustriestoscarringofrecreationalareasandparks(WorldResourcesInstitute1992:208).

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BarrenlakesthroughouttheworldrevealtheindirectdamagethatcanbecausedbySO2.Theconcentrationofhydrogenionsinacidrainis5to100timesthatindistilledwater.Whenacidrainfallsinareaswherethebedrockisgranite,orwhereothermaterialispresentthatisincapableofneutralizinghydrogenions,itisespeciallyinjurious(U.S.Congress1987).Astheconcentrationofacidgrowsinlakes,marinelifefromalgaetobrooktroutdies,leavingaclearbutbarrenbodyofwater.IntheUnitedStates,lakesinNewYork'sAdirondackmountainsandinthemountainsofnorthernNewEnglandareendangeredbyannualdepositsofasmuchas4metrictonsofsulfuricacidpersquarekilometer.Morethan200sterilelakescanbefoundintheAdirondacksalone,allofthemvictimsofacidrain.InEurope,heavilyindustrializedregionsareprimarysourcesofacidrain.Inadditiontothelocaldamagetheycause(seeBox3.2),SO2emissionscanwreakhavocondistantecosystems.Morethan50percentofthesulfurdepositioninFinlandisattributedtoemissionsfromothercountries.EmissionsfromCentralEuropeandtheU.K.havealsoacidifiedsome7,000squaremilesoflakesinsouthernNorway(WorldResourcesInstitute1993:544).

Box3.2SO2andEffectsofAcidRainintheCzechRepublic

SulfurdioxideemissionsandacidrainhavecausedseveredamagetotheenvironmentandthepopulationintheCzechRepublic.

EnergyconsumptionintheCzechRepublic(whichpartedcompanywiththeSlovakRepubliconJanuary1,1993)isquitesubstantialandhasbeentheleadingcauseofenvironmentalharmsinceWorldWarII.Oneofthekeyproblemsisthattheprimaryfossilfuelislignite(browncoal),whichhasaverylowcaloriccontentanda

highsulfurcontent(5to10percent).Ligniteisstripminedprimarilyinasmall(2,500km2)regionofthecountry,NorthernBohemia,thatishometo500,000inhabitants.Theregionharborsthecountry'shighestconcentrationofcoal-firedpowerplantsandproduces45percentofallSO2and40percentofnitrogenoxideemissionsfortheentireCzechRepublic.

OnlyafewforestsintheRepublicremainhealthy;thousandsofhectaresoflandhavebecomebarrenfromthedailyonslaughtofacid.InNorthernBohemiaandsurroundingareasinparticular,thesoilissoacidic(pHof4.3to2.3)thatitisunabletosupportlifeofanykind.Withthedemiseofforests,soilerosionisinevitable.

DecreasedlifeexpectancyinsomeareasoftheCzechRepublichasbeenattributedtothedetrimentaleffectsofSO2pollution.InNorthernBohemia,theaveragelifespan(foraman,65.4years;forawoman,73.3years)istwoyearslessthanthecountry'saveragelifeexpectancy.Moreover,thepeopleofNorthernBohemiasufferfrombronchitisandotherdiseasesoftheupperrespiratorytractandallergiesatrates260and300percenthigher,respectively,thantheCzechRepublic'spopulationasawhole.

Source:Havlicek(1993).

SO2emissionsalsohavedamagedEurope'sheritageofoutdoorsculptureandarchitecture.SmoghangsoverAthens;theSO2inthesmogcanturnmarbleandotherstoneintogypsumthatiswashedawaybyrain.Greece'soutdoormonumentsand

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statues,includingthepricelessruinsontheAcropolis,havebeenpockedanddiscoloredbythischemicalreaction.Moredamagehasbeendoneinthe20thcenturythaninthepreceding2,000years.AcidicparticlesalsothreatenstonemonumentsinItaly.Morethan8milliontouristsvisitGreeceeachyear,andabout50millionvisitItaly(WorldResourcesInstitute1993:532,540).Damagetohistoricartifactsandbuildingscouldproduceadecreaseintourism,followedbyadeclineintheireconomies.

Ozone

Ozoneisabluishgaswithapungentodorthatispresentintheatmospherefromtheearth'ssurfaceuptoatleast100km.Dependingonitsconcentrationanddistancefromtheearth'ssurface,ozonecanhaveeitherharmfulorbeneficialeffectsontheenvironmentandonthehealthofindividuals.Ozonefoundneargroundlevel(within10to15kmoftheearth)isreferredtoastroposphericozoneandcomprisesapproximately10percentofatmosphericozone.Ozonefoundataltitudesof15kmormoreisknownasstratosphericozoneandcomprises90percentormoreofatmosphericozone.

Dynamictransportofmaterialsfromthetropospheretothestratosphereandviceversaisimportanttothechemicalcompositionofbothregions.Globaltroposphericchemistryisimportanttotheoverallatmosphericbehaviorofozone,sinceprecursormolecules,suchasNO2,andsinkmolecules,suchasNOandCl,arederivedfromorremovedinthetroposphere.

Ground-LevelOzone

OzonemeasurementsnearthegroundinthemiddleandhighlatitudesoftheNorthernHemispherehaveincreasedoverthepastfewdecadesatarateof1to2percentperyear.Aslittleas0.2ppmofozoneneartheearth'ssurfacepromotestheformationofsmog.Troposphericor

ground-levelozoneisformedintheatmospherethroughacomplicatedseriesofchemicalreactionswhenitsprecursors,hydrocarbonsandnitrogenoxides,combineinthepresenceofsunlight(seeBox3.3forasimplifiedchemistryoftroposphericorground-levelozoneformation).Thereactivehydrocarbons,volatileorganiccompounds(VOCs),areproducedbyseveralsources,includingmotorvehicleemissions,evaporationofsolventsandgasoline,chemicalmanufacturing,petroleumrefining,andtoalesserdegreewastedisposalsitesandwastewatertreatmentplants.

Thenitrogenoxides(NOx)arisemainlyfromcombustionoffossilfuels.GroundlevelozoneisoneofmorethanahundredcompoundsformedwhenVOCsandNOxreactchemicallyinthepresenceofsunlight.Theresultingmixtureisknownasphotochemicalsmog.PhotochemicalsmogwasinitiallynotedinLosAngeles,butitisnowcommoninmanycitiesinEurope,Japan,SouthAmerica,andelsewhereintheUnitedStates.BrightsunnymorningswithrelativelyhighlevelsofNO2areidealforsmogformation,asarehightemperatures.Ozoneconcentrationsarelowestaroundsunrisenearzeroinmosturbanareasandreachamaximumconcentrationintheearlyafternoon.SeeFigure3.1foraprofileofdailypollutionconcentrationsinLosAngeles.Ozoneformationisaggravatedwhentemperature-inducedairinversionstrapthecomponentsthatformsmog.

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Box3.3ChemistryofTroposphericOzoneFormation

Thechemicalreactionsgivenbelowareasimplifiedversionofthecomplexseriesofchemicalreactionsthatoccurduringtheformationoftroposphericorground-levelozone.Sunlightisessentialbecauseitprovidestheenergynecessaryforthesereactionstooccur.Thephoto-oxidationofCO,CH4,andhydrocarbons(foundintheatmosphere)givesrisetoavarietyofcomplexorganicperoxyradicalsrepresentedasNitrogenoxide(NO)inairreactswiththeseperoxyradicalstoformnitrogendioxide(NO2):

Thekeystepinsmogformationisthephotodissociationofnitrogendioxide:

Theabovereactiontakesplaceattheedgeofthevisibleregionintheatmosphere(392nm).TheoxygenatomsproducedreactwithsurroundingO2moleculestoformozone:

Note:(g)=gasphase.SeeWorldMeterologicalOrganization(1985:117-50)foradetailedaccountoftroposphericchemistry.

Source:WorldMeteorologicalOrganization(1985:119,127);Mastersonandothers(1985:536-37).

Figure3.1AverageConcentrationsofNO,NO2,andO3atVariousTimesofDayinLosAngeles

Source:Mastersonandothers(1985).

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Table3.3givesthehighesthourlymaximumlevelsoftroposphericozoneinselectedcitiesaroundtheglobe.Mostofthemetropolitanareasmonitoredforozoneexceededtheshort-term(1hour)WHOguidelinesforozoneof150to200mg/m3(0.0766to0.1005ppm).

Table3.3OzoneLevelsinSelectedCities,1989Concentration

Metropolitanarea Population ppm mg/mTokyo-Yokohama 28,700,000 0.0738a 145MexicoCity 19,400,000 0.4050 793NewYork 17,400,000 0.2780 545SãoPaulo 17,200,000 0.1549 304BuenosAires-LaPlata 12,400,000 0.0560b 110bLosAngeles 11,500,000 0.3500 686Paris 10,000,000 0.1170 229Karachi 7,300,000 0.0900 176Tianjin 5,625,000 0.1900 372SanFrancisco-Oakland-SanJose 5,225,000 0.1500 294HongKong 5,175,000 0.1070 210Nagoya 4,925,000 0.0699b 131Santiago 4,700,000 0.3990 782Johannesburg 4,600,000 0.1200 235Berlin(EastandWest)d 3,940,000 0.2600 509Houston 3,225,000 0.2300 450Guadalajara 3,100,000 0.1900 372Montreal 2,950,000 0.1550 303Naples 2,925,000 0.0780b 137SanDiego-Tijuanad 2,720,000 0.2500c 489Budapest 2,575,000 0.1100 216CapeTown 2,425,000 0.1030 202Note:Highesthourlymaximumin1989orlatestavailableyearfromresponsestoPopulationCrisisCommitteequestionnaire.aAverageconcentrationfortwoyears.bMeasuresmorethan1hour.cSanDiegoonly.dInternationalcities:DataareprovidedseparatelyforSanDiego-Tijuanabutnotfor

dInternationalcities:DataareprovidedseparatelyforSanDiego-TijuanabutnotforEastandWestBerlin.Source:Camp(1990).

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HealthandEnvironmentalEffectsofOzoneandOtherPhotochemicalOxidants

Thephotochemicalreactionofhydrocarbonswithoxidesofnitrogenproducesmanyphotochemicaloxidants,mostofwhicharecolorlesstoxicgases.Apartfromozone(O3),theseincludeformaldehyde(HCHO);peroxyacylnitrate(CH3[CO]OONO2),commonlyabbreviatedasPAN;acrolein(CH2CHO);andperoxybenzoylnitrate(PBzN).TheeffectofozoneatdifferentconcentrationsisgiveninTable3.4,andTable3.5providesarecentupdateontheshort-termoracuteeffectsofozoneonhealthyindividuals.Theeffectsoflong-termorchronicexposuretoozonearepoorlydefinedandshouldbestudiedmoreintensively.ThedetrimentaleffectsofozonemayalsobecausedbythesynergiesbetweenNO2,acidsulfate,andotherphotochemicaloxidants.

Excessivelevelsofozonehavebeenfoundtobeharmfultopeople.Evenshort-termexposuretoozonecanresultincoughing,painfulbreathing,andtemporaryreductionoflungfunctionafteroneortwohoursofexercise.Repeatedexposuretoozonemayresultinretardationoflungdevelopmentinchildren,acceleratedagingofthelung,permanentimpairmentoflungfunction,andthedevelopmentofchroniclungdiseasessuchaspulmonaryfibrosis.Manyindividualsexposedtoozonesuffereyeirritationandasthmaattacks.Ozone'sprecursors,NO2andVOCs,alsoposeathreattohumanhealthandtheenvironment.NO2isarespiratoryirritant,whereasVOCsarerespiratoryandeyeirritantsandmayalsobecarcinogenic.InJuly1992,whenozoneinAthenssurpassedthedangerouslevelandNO2alsoreacheddangeroushighs,manypeoplewenttohospitalswithheartandrespiratorycomplaints(Walsh1992b:19).

Onthebasisofstudiesofthehealtheffectsofshort-term(one-hour)exposuretoozone,EPAhasconcludedthat0.12ppm(240mg/m3)is

thepermissibleexposurelevel.Butozoneconcentrationsatlevelsbelow0.12ppmhaveadverseeffectsifexposureisprolonged(about6hours;ChiltonandSholtz1989).A1991studyconductedbytheAmericanLungAssociationrevealedthathealthyyoungadultssufferedfromareductioninlungfunction,aswellaswheezing,coughing,andchestirritationwhenexposedtoozoneconcentrationsof0.08ppm(Walsh1994a:1314).Hence,thecurrentEPAstandardmaynotbelowenoughtoprotectpeoplewhoareexposedforlongperiods,andrevisionofthestandardiscontemplated.

Elevatedozonelevelsalsoaffectvegetation.Visiblesignsofexposureincludelightflecks,darkstipples,andyellowspotsorpatchesonleaves,theseareindicationsofprematureaging.OzonemayalsobecontributingtothedeclineoftreespeciesintheUnitedStates,Canada,andEurope.ThedeclineofponderosaandJeffreypinesintheSanBernardinoMountainseastofLosAngelesandthedeclineofeasternwhitepinetreesacrosstheEasternUnitedStates,forexample,havebeenattributedprimarilytoozone(OfficeofTechnologyAssessment1989).

Table3.4EffectsofOzoneatVariousConcentrationsConcentration(partspermillion)

Effectsa

0.01 Odorthreshold0.02for8hours Damagetotobaccoleavesbegins0.03for8hours Significantdamagetotobaccoleaves0.05 Noseandthroatirritationthreshold0.05for1hour Damagetotobaccoleavesbegins0.10for1hour Significantdamagetotobaccoleaves;pinetreeneedletipsburn0.05 Thresholdforeyeirritationinsensitivepeople(ambientoxidant)0.15b Eyeirritationthresholdformostpeople(ambient)0.10 Reductioninoxygenconsumptionandbloodoxygentension

(concentration)levelsinemphysemapatients0.1to0.25longterm Shortenslifespanofguineapigs0.10for8hours Definitesymptomaticeffectsinsensitivepeople0.20for3hours Decreaseofvisualacuity0.60 Coughirritationthreshold,pronouncednoseandthroatirritation1for1-1/2hour Coughing,irritation,severeexhaustion3to12forafewhours

Lethaltosmalllaboratoryanimals

Note:WHOguidelinesare0.076to0.1ppm(150to200mg/m3)for1hourexposureand0.05to0.06ppm(100to120mg/m3)for8hourexposure.aAsconcludedfromlaboratoryexperimentsutilizingozoneexceptwhereotherwiseindicated.Ambientmeasurementsarefor''totaloxidants."b0.25ppmbythephenolphthaleinmethod.Source:U.S.DepartmentofTransportation(1984).

Table3.5HumanResponsetoSingleOzoneExposureResponse Subjects Exposureconditions

510%meandecrementinFEBa

Healthyyoungmen

0.18ppmwithintermittentheavyexercisefor2hoursO3inpurifiedair0.1ppmwithmoderateexercisefor6.6hoursOinpurifiedair0.1ppmwithveryheavyexercisefor0.5hourinambientair

Healthychildren 0.1ppmnormalsummercampprogramOpurifiedair

Increasedcough Healthyyoungmen

0.12ppmwithintermittentheavyexercisefor2hoursO3inpurifiedair

Healthyyoungmen

0.08ppmwithmoderateexercisefor6.6hoursO3inpurifiedair0.12to0.13ppmheavyexercisefor16to28minutesO3inpurifiedair

Reducedathleticperformance

Healthyyoungmen

0.18ppmwithexerciseatVEbof54L/minutefor30minutes,120L/minutefor30minutesOpurifiedair

Healthyyoungmenandwomen

0.12to0.13ppmwithexerciseatVEbof30to120L/minute16to28minutesO3inpurifiedair

Increasedairwayreactivity

Healthyyoungmen

0.08ppmwithmoderateexercisefor6.6hoursO3inpurifiedair

Healthyyoungmenwithallergicrhinitis

0.18ppmwithheavyexercisefor2hoursOpurifiedair

Increasedairwaypermeability

Healthyyoungmen

0.4ppmwithintermittentheavyexercisefor2hoursO3inpurifiedair

Increasedairwayinflammation

Healthyyoungmen

0.08ppmwithmoderateexercisefor6.6hoursO3inpurifiedair

Acceleratedtracheobronchialparticleclearance

Healthyyoungmen

0.2ppmwithintermittentlightexercisefor2hoursO3inpurifiedair

aForcedexpiratorybreathing.bExpiratoryvolume.

bExpiratoryvolume.Source:AdaptedfromRomieu(1992:19).

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Upper-LevelOzone

Ozoneisbothproducedanddestroyedintheupperatmosphere(seeBox3.4forthesimplifiedchemistryofupper-levelorstratosphericozoneformation).Satellitemonitoringoftheupperatmospherehasshownthattheozonelayerataltitudesof28to35kmisbeingdepletedandthatasmuchas5percentoftheozoneatthe45kmlevelhasdisappeared.

Box3.4ChemistryofStratosphericOzoneFormation

Ozoneisproducedintheupperatmospherewhenoxygenmoleculesabsorbsolarultravioletradiation.First,oxygenatoms(O)arereleasedbythephotodissociationofmolecularoxygen(O2)byshort-wavelengthultravioletradiation(<243nm):

ThisisfollowedbyacollisionbetweenanOatomandanO2moleculetoproduceanunstablemoleculeofthreeoxygenatomsknownasozone(O3):

Note:(g)=gasphase;E=hn,whereE=energy,h=Planck'sconstant,n=frequencyoflight.SeeWorldMeteorologicalOrganization(1985:2756)foramoredetailedaccountofstratosphericozonechemistry.

Source:Mastersonandothers(1985).

Depletionofstratosphericozonehasimportantdetrimentaleffectsonhealthandtheenvironment.StratosphericozoneshieldstheearthfromultravioletB(UV-B)radiationfromthesun.A1percentdecreasein

ozoneintheatmospherecausesa2percentincreaseinUV-Bradiation,whichinturnmayresultina4percentincreaseinskincancer(Titus1986:1).IncreasesinUV-Bradiationcanalsocauseeyecataractsandinjuretheskin'simmuneresponses.

Severalfactorssuchasmeteorologicalconditions,type,andconcentrationsofindustrialchemicalscontributetoozonedestructioninthestratosphere.Theprincipalchemicalsinvolvedarenitrogenoxideandchlorofluorocarbons(Box3.5givesabriefdescriptionofthecomplexchemicalprocesses).

CFCsandStratosphericOzoneDepletion

Theindustrialchemicalsknownaschlorofluorocarbons(CFCs)yieldchlorineatoms(Cl)throughaseriesofcomplexchemicalreactions.TheClatomsarethedirectcausesofthedepletionoftheozonelayer.CFCsareprimarilyresponsibleforthefactthatozone-depletingchlorinatedcompoundsinthestratosphereare4to5timeshigherthannormal.UnlessfurtherstepstocurbCFCemissionsaretaken,chlorinecompoundsinthestratospherewillincreaseatapproximately5percentperyear(GraedelandCrutzen

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Box3.5DepletionofStratosphericOzone

Ozonemoleculesdecaytoanoxygenmoleculeandanoxygenatomwithintheozonelayer.Thishappensinseveralways;oneofthemostimportantisthedirectcollisionofanozonemolecule(O3)withanoxygenatom(O):

RoleofNitrogenOxideinOzoneDestruction

Certainsinkmolecules,suchasNOandchlorine,actascatalystsinthedecompositionofozone.ThesemoleculescompetewithO2moleculesforfreeoxygenatomsintheozonelayerandhinderozoneformation.Ozoneisdepletedintwosteps:

NOmolecule:

Overallreaction:

Theoverallreactionisthesameaswhenanozonemoleculecollideswithanoxygenatom.

RoleofCFCsinOzoneDestruction

Sincethemid-1970s,CFCshavebeenrecognizedasasourceofchlorineinthestratosphereandhenceathreattotheozonelayer.CFCsareunaffectedbynaturalcleansingmechanisms,suchasrainfall,andescapeintothestratospherewithintenyears,wheretheysurvivefor

about400years.Freongases,suchasCFCl3andCF2Cl2,areasourceofchlorine(Cl)atomsintheupperatmosphere.ThesecompoundsdecomposetoformClatomswhenexposedtoultravioletradiationat200nm.Atanaltitudeof40km,lightofthiswavelengthisfreelyavailable:

Thechlorineatomsactascatalysts(whichacceleratetherateofachemicalreactionandarefreedunalteredattheend)inthedecompositionofstratosphericozone.First,thechlorine(Cl)breakstheozoneintoordinaryoxygen(O2)andanoxygenatom(O).Itthencombineswiththefreeatomtoformchlorinemonoxide(ClO):

ThisisthenstrippedofitsOatombyanotherfreeOatomthatcombineswithittogivemolecularoxygen(O2).Thechlorineatom(Cl)isleftintactandcanrepeatthiscycle100,000timesbeforeitisfinallyneutralized:

IthasbeensuggestedthattheCl-catalyzedreactioncouldultimatelydecreasetotalozoneintheupperatmosphereby5to9percent.UseofCFCsasaerosolpropellantshasbeenphasedoutintheUnitedStates,Canada,andSweden.

Note:(g)=gasphase.SeeWorldMeteorologicalOrganization(1985:2756)foradetailedaccountofstratosphericchemistry.

Source:WorldMeteorologicalOrganization(1985:

2938);Mastersonandothers(1985:527-28).

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1990:1718).CFCsareusedasrefrigerants,solvents,propellantsinspraycans,andblowingagentstoproducefoam.TheinertnessofCFCsintheloweratmospherewasinitiallyconsideredapositiveattributeinpreventingCFCsfromposingadirectthreattolivingorganisms.Unfortunately,thisalsoallowsCFCstoreachtheupperatmosphereunchanged,wheretheyarebrokenapartbyexposuretostrongsunlight,beginningachainreactionleadingtothedestructionofozone.BeforetheinventionofCFCs,ozoneconcentrationinthestratospherewas220Dobsonunits(Dobsonunitsarethestandardozonemeasure).By1987theozonereadinghadfallento120Dobsonunits.Itwasaboutthesamein1990,butin1992arecordlowmeasurementof105DobsonunitswasobtainedovertheAntarctic(Walsh1992a:8687).

TheUnitedKingdom's1993StratosphericOzoneReportstatedthatozonedepletionisworseninginEurope,withrecordlossesoccurringintheNorthernHemisphere'smid-latitudes.Thereportattributesthe3percentperdecadelossofozonetochlorineandbromine.ThereportalsostatesthattheaveragethicknessoftheglobalozonelayerfromMay1992toMay1993measuredbytheTotalOzoneMappingSpectrometerwas3percentlessthaninanyyearsince1978,whenmeasurementscommenced(Walsh1994b:78).TheNationalOceanicandAtmosphericAdministrationfounda5to18percentdecreasebelowaverageconcentrationintheozonelayerovertheUnitedStatesduringtheperiodJanuary1992toMay1993.Theseverestthinning(18percent)occurredfromMarchthroughMay1993.Thesevaluesarerecordlowsforthepast20years.BelgiumandtheNetherlandsalsoreportedalossof17to18percentbelowaveragelevelsforozonebetween1971and1993.TherecordlowsmayberelatedtotheJune1991eruptionofMountPinatubo(Walsh1993b:12),whichspeweddropletsofsulfuricacidintotheatmosphere.Thesedropletsprovidesurfacesforgeneratingtheozone-destroyingreactiveformsof

chlorine.

ThemostalarminglossofstratosphericozonehasbeenobservedoverAntarctica.SixscientistswhospenttwomonthsintheAntarcticin1990wereexposedtosunlightthroughagiganticholeintheozonelayer.Unlesstheyworeprotectiveclothing,theywereseverelyburnedandbecamenauseatedafterexposureofjustafewhours.Exceptionallyhighconcentrationsofozone-depletingClOmoleculeshavebeendetectedintheAntarcticstratosphere(EnvironmentalUpdate1990),andasimilarsituationmaynowbeoccurringinthehighnorthernlatitudes.Approximately1.5ppbbyvolumeofClOhavebeendetectedinthestratosphereoverthehighnorthernlatitudes,aconcentrationcomparablewiththatfoundintheAntarctic(Walsh1992c:8586).

RelevancetoDevelopingCountries

Asstatedatthebeginningofchapter2,littlemeaningfulworkhasbeendoneinthedevelopingcountriestomonitorairpollutantsandassesstheireffectsonadults,children,andtheenvironment.AvailabledataindicatethatemissionsofallmajorpollutantsSO2,suspendedparticulatematter,CO,andNOx,andleadaregrowingindevelopingcountries;noneofthesecountrieshaveissuedozone,particulate,orother

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pollutionalerts.Thepollutantsdiscussedinchapters2and3arepresentinalmostallmajorcitiesinsome,atlevelsthatmayhaveacriticalimpactonhealth.

Governmentsandindustriesaremakingmajoradvancesineffortstofindalternativestoozone-destroyingCFCsandhalons,forexample(seeAhmed1994b).Withafewsalientexceptions,however,developingcountrieshavebeenrelativelyslowtoincorporatenewproductsandtechnologies.

Theinactioninmostdevelopingcountriesisnottheproductofignorance;mostdevelopingcountriesrecognizetheneedtotakecorrectivemeasurestomanageairpollution.Theyareunabletoactbecauseofcompetingclaimsforlimitedresourcesandbecausemanylegislatorsandpolicymakersmisperceivetheextentoftheproblem,therelativecostsofamelioration,andthedangersofinaction.

Sincemorethan50percentofallairpollutantsareemittedbyindustrializedWesterncountries,itisfortunatethatthesecountrieshaveboththefinancialandtechnicalresourcestoimplementsuccessfulpollutioncontrolstrategies.ThatsuchstrategiesarehavinganeffectisindicatedbythedownwardtrendsinSO2,suspendedparticulatematter,andleadlevelsinthesecountries.Meanwhile,however,pollutionlevelsindevelopingregionsareincreasing.OfparticularconcernistheworseningairpollutioninpopulousdevelopingareasinLatinAmerica,China,India,andSoutheastAsia.Itisestimatedthatbytheyear2000,everyotherpersonwillbeanurbanresident,andoneinthreepersonswillliveinacityofatleast100,000people.Eightoutof10peoplewillliveinadevelopingcountry.

Airpollutionhasnoboundaries,andemissionsintheIndiansubcontinentorAfricacouldultimatelyaffecttherestoftheworld.Airqualitymanagementwillrequiretheexperienceandtechnical

expertiseaswellasfinancialassistanceoftheindustrializedworldandwouldinthelongrunbenefitbothdevelopedanddevelopingcountries.Forthesereasons,itisusefultoexaminesomebasicaspectsofaprogramtoadaptairqualitymanagementtothepresentandemergingneedsofdevelopingcountries.

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4AmbientAirQualityandEmissionStandardsInmostdevelopingcountries,formulatinganairqualitymanagementprogramgenerallyhasalowerprioritythanimplementingprogramstopromotehousing,generateelectricpower,orprovidesocialservices,education,andmedicalcare.Countrieswithlimitedfinancialmeansmustmakedifficulteconomicandpoliticalchoicesabouthowtoallocatetheirresources,andgenerallytheypursueprogramsthatwillshowthemostvisibleresults.Giventheirprioritiesandconstraints,thedevelopingcountriesmaynotbeabletoimplementthesamecleanaircontrolsastheindustrialcountriesintheshortormediumterm.Butnocountrydevelopedordevelopingcanaffordtoignoretheneedforprogramstoachieveminimumlevelsofcleanair.ThischapterdiscussescurrentandproposedairqualitystandardsinvariousdevelopedanddevelopingcountriesandreviewsthestandardsproposedbytheWorldHealthOrganization(WHO).

AirQualityStandards

Measurements

Theharmfuleffectsofanairpollutantaredeterminedinpartbyitsvolumeconcentrationandbyitsdurationintheatmosphere.Partspermillion(ppm)isthestandardmeasureofthevolumeofairpollutants;partsperhundredmillion(pphm)andpartsperbillion(ppb)areusedforverylowconcentrations.(1ppmisequivalentto10(-4)percent;theoxygencontentinairis20.946percent,equalto209,460ppmbyvolume.)Theothermeasureofvolumeisfoundedonweightperunitvolume,andtheunitsarerepresentedasmicrogramspercubicmeter(µg/m3).Thismeasurementisassociatedwithppmat25°C(77°F)andoneatmospherepressure(BellomoandLiff1984:2627).

Differenttechniquesareusedtomeasureairpollutantconcentrations.Thesetechniquesrangefromsimplemeasuringprocedurestocomplexsimulationsthattracedispersedpollutantsthroughtimeandspace.Computerprogramsareavailablethatcanpredictlevelsofemissionsunderdifferentconditions.

TypesofStandards

Airqualitystandardsareintendedtopreventconcentrationsofairpollutantsfromreachingharmfullevels.Twostandardsarewidelyused.Emissionstandardspertainto

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pollutantscomingfromspecificsourcessuchasindustrialsmokestacksandmotorvehicleexhaustsystemsandspecifyallowableconcentrationsofpollutantsatreleasesites.Ambientstandardsareconcernedwiththeoverallairqualityofacommunityorindustrialareaandspecifyallowablepollutantconcentrationsinsuchareas.Emissionstandardsmakeitpossibletoidentifyspecificsourcesofairpollutionandtodesigncorrectiveactions.Ambientstandardsaredefinedwithanadequatemarginofsafetytopreventharmtohumanbeingsandtheenvironment.

Ambientairqualitystandardsareoftensubdividedintoprimaryandsecondarystandards.Theprimarystandardsareintendedtoprotecthumanhealthandhaveamarginofsafety;economicandtechnicalfeasibilityaredisregarded.Primarystandardsalsoestablishdeadlinesforcompliance.Secondarystandardsrefertoenvironmentaleffectsandareintendedtoprotectoverallorlong-termhumanwelfare.Theypertaintovisibility,soil,water,vegetation,domesticanimals,wildlife,materials,property,transportation,andeconomicissues.Secondarystandardscanbeattainedatamoreleisurelypace.

AmbientAirQualityStandards

Table4.1givesambientairqualitystandardsinselectedcountries.ThosegivenfortheUnitedStatesareprimarystandardsandarebasedonworkbytheEPA,otherregulatoryagencies,andindustry.BrazilandIndonesiahaveambientairqualitystandardsthatareverysimilartothoseoftheUnitedStates,anditisnotapparentwhetherthesestandardsweresetindependentlybyBrazilandIndonesiathemselvesorsimplyechotheU.S.standards.

ChinaandIndiaestablishedambientairqualitystandardsin1982.UnlikeJapan,theUnitedStates,andseveralEuropeancountries,whichhavenationwidestandards,ChinaandIndiahaveambientstandardsthatvaryinregionswherelivingconditionsdiffer.Because

oftheircomplexity,thesestandardsaregiveninseparatetables(Tables4.2and4.3).ThelimitssetforheavilypollutedareasinChinaarethreetimesashighasthelimitssetfornaturalconservationareas.ThestringencyofIndia'sstandardsvarieswithregionaldesignationsmadebyStatePollutionControlBoardsonthebasisoflanduseandotherfactors.TheClassIIstandardsinChina,andthosepertinenttoregionsdenoted"B"inIndia,typicallyconcernresidentialandcommercialregions.ApartfromIndia'sparticulatestandards(whicharelessstringent)andChina'scarbonmonoxidestandards(whicharemorestringent),thesestandardsdonotvarygreatlyfromthestandardsinJapan,Sweden,andtheUnitedStates,andcanbeconsideredadequatetosafeguardpublichealth.

Table4.4furnishesambientairqualityvaluesgivenbytheWorldHealthOrganization.Thesevaluesareguidelinesratherthanstandards.Theysignifythelevelandexposuretimeatwhichnodetrimentaleffectsareanticipatedandbelowwhichthereisnoexpectedhazardtothehealthofpeople.Anoteofcautioniswarranted,sinceguidelinesareprovidedonlyforindividualpollutants;exposuretoamixtureofpollutants(noneofwhichbyitselfexceedstheguidelines)mayhavedetrimentaleffects.

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Table4.1ComparativeAmbientAirQualityStandardsof14Countries/EconomiesandTwoInternationalOrganizations

Pollutant: TSPg SO2 CO NOx LeadConcentration: µg/m3 ppm ppm ppm ppm µg/mSamplingtime: 24hours 24hours 8hours 1hour (seenotes) (seenotes)

Brazila 240 0.14 9.0 0.08 0.25HMiChilea 260 0.14 9.0 0.08 0.16DMjIndonesiab 260 0.10 20.0 0.10 0.05DMj 60.024hr.Japanc 100 0.04 20.0 0.06 0.040.06DMjKoreac 300 0.15 20.0 0.1 0.15HMiKuwaitc 350 0.06 10.0 0.08 0.05DMj 2.024hr.Malaysiac 260 0.04 9.0 0.10 0.17HMi 3.0QAMexicod 275 0.13 13.0 0.11 0.21HMiPeruc 350 0.30 17.0 0.20(30min.) 0.11DMj 15.0MASaudiArabiac 340 0.15 9.0 0.15 0.35HMiTaiwanc 250 0.10 9.0 0.12 0.25hmn 1.0MMThailande 330 0.11 17.0 0.10 0.17hmn 10.024hr.Turkeyf 300400 0.15 0.16DMj 2.0AAMUSAc 260 0.14 9.0 0.12 0.05AAMo 1.5QAEECf 300 0.15 2.0AAMWHOd 150230 0.04 9.0 0.10 0.05(8hours) 0.51.0Note:=notavailable.;µg=1x10-6gm;mg=1x10-3gm;ppm=partspermillion;µg/m3=ppmx40.91xMW,whereMW=molecularweight;(H=1,C=12,N=14,O=16,S=32);SO2=sulfurdioxide;NOx=nitrogenoxide.aWeitzenfeld(1992).bSinha(1989).cMurley(1991).dFaizandothers(1990).e1994WorldBankdata.fSebastian(1990).gTotalsuspendedparticulates.hPhotochemicaloxidants(ozone).iHourlymaximum.jDailymean;meanconcentrationnottobesurpassedbyanydailymean.kQuarterlyaverage(3months).

kQuarterlyaverage(3months).lMonthlyaverage.mMonthlymean:themathematicalmeanvalueofeachdailymeanvalueobtainedinamonth.nHourlymeanvalue.oAnnualarithmeticmean.

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Table4.2China'sNationalAmbientAirQualityStandards(µg/m3)Pollutant Averagingtime Firstclassa Secondclassb ThirdclassTSP Dailymeand 150 300 500

Notoncee 300 1000 1500Flydust Dailymeand 50 150 250

Notoncee 150 500 700SO2 Annualdailymeanf 200 600 100

Dailymeand 50 150 250Notoncee 150 500 700

NOx Dailymeand 50 100 150Notoncee 100 150 300

CO Dailymeand 4000 4000 6000Notoncee 10,000 10,000 20,000

O3 Hourlymean 120 160 200Note:µg=1x10-6grams;TSP=totalsuspendedparticulates;SO2=sulfurdioxide;NOx=nitrogenoxides;CO=carbonmonoxide;O3=ozone.aNaturalconservationareas,scenicspots,historicalsites,andconvalescentplaces.bResidentialareas,mixedareasofbusiness,culturalareas,historicalsitesinrelevanturbandevelopmentprograms,andopenareas.cCities,towns,andindustrialareashavingseriousairpollutionproblems,aswellasurbantrafficcentersandmainroads.dMeanconcentrationlimitnottobesurpassedbyanydailymean.eConcentrationlimitnottobesurpassedevenonceinsamplinganddetermination.fMeanconcentrationlimitnottobesurpassedbyanydailymeaninanyyear.Source:Faizandothers(1990).

Table4.3India'sAmbientAirQualityStandards(µg/m3)Pollutant Averagingtime AreaAa AreaBb AreaC

TSP 8-houraverage 500 200 100SO2 8-houraverage 120 80 30CO 8-houraverage 5,000 2,000 1,000NOx 8-houraverage 120 80 30O3Note:=notavailable;µg=1x10-6grams;TSP=totalsuspendedparticulates;SO

Note:=notavailable;µg=1x10-6grams;TSP=totalsuspendedparticulates;SOsulfurdioxide;NOx=nitrogenoxides;CO=carbonmonoxide;O3=ozone.aIndustrialandmixedareas.bRuralandresidentialareas.cSensitiveareas.Source:Siddiqi(1984).

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Table4.4WorldHealthOrganizationGuidelinesforAmbientAirQualityStandardsPollutant Samplingtime Standard

Particulatematter Annualmean 4060µg/m3b,d98percentilec 100150µg/m3b,dAnnualmean 6090µg/m3b,d98percentilec 150230µg/m3b,d

Thoracicparticles(PM10)a 24hours 70µg/m3bSO2 Annualmean 4060µg/m3b,d

98percentilec 100150µg/m3b,d10minutes 500µg/m31hour 350µg/3

CO 15minutes 100mg/m330minutes 60mg/m31hour 30mg/m38hours 10mg/m3

NO2 1hour 400µg/m324hours 150µg/m3

Lead Annualmean 0.51.0µg/m3Photochemicaloxidants(O3) 1hour 150200µg/m3

8hours 100120µg/m3PAHs n.a. NoguidelinesyetNote:n.a.=notapplicable;µg=1×10-6grams;mg=1×10-3gm;SO2=sulfurdioxide;NO2=nitrogendioxide;CO=carbonmonoxide;O3=ozone;PAHs=polynucleararomatichydrocarbons.aUNEPandWHO(1992).bValuesgivenareforthecombinedeffectofSO2andsuspendedparticulatematter.Thesefiguresmaynotbeapplicablewhenonlyonecompoundispresent.cOfthedailymeans,98percentneedtobebelowthisconcentration.dStandardestablishedforblacksmoke.Source(exceptasnoted):UNEPandWHO(1988).

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EmissionStandards

Anemissionstandardisalegallimitonthequantityofapollutantanindividualsourceisallowedtoemit(Tietenberg1992:372).Emissionstandardshavebeensetbymostindustrializedcountriestocurbpollutionfrombothstationaryandmobilesources.Stationarysourcesusuallyinvolvepowergenerationandindustrialprocesses.Themanydifferentmanufacturingprocessesmayemitdifferenttypesofpollutants.Hence,emissionstandardsareindustry-andsite-specific.Althoughmobilesourcesemitmanyofthesamepollutantsasstationarysources,theiremissionsaremoredifficulttocontrol,anditismoredifficulttotailoremissionratestolocalpollutionpatterns.Thesedifficultiesmaybeattributedtotheintrinsicallytransientnatureofvehiclesourcesevenwithinametropolitanareaandtothepossibilitythataparticularvehiclewilltraveltomanydifferenturbanandruralareasduringitsusefullife(Tietenberg1992:450).Mobilesourcesarealsomorenumerousthanstationarysources,addingtothedifficultyofcontrollingtheiremissions.

Transport-RelatedEmissions

Thetransportationsectorisasignificantcontributortoairpollution.Forexample,emissionsfromtransportationsourcesinFrancein1990accountedforabout76percentofemissionsofCO,69percentofHCs,56percentofNOx,30percentofparticulates,21percentofSOx,and80percentoflead(Faiz1993).Motorvehiclesarethelargestcontributorsofmobile-sourceemissions(seeTable4.5).

Table4.5TransportSectorContributiontoNationwidePollutantEmissionLevelsinFrance,1990

(%oftotalanthropogenicemissions)Modeoftransport CO HC NOx SPM SOx

Motorvehicles 76 69 48 26 8Railways .. .. 1 1 ..Aviation(withinairports) .. 1

Coastalnavigation .. .. 7 3 12(NorthSeaandMediterranean)

TOTAL 76 69 56 30 21..=Lessthan1percentcontribution.=notavailable.Source:AdaptedfromFaiz(1993).

Table4.6givesthecontributionofthetransportsectortoconventionalairpollutantemissionsinselectedcountries.ThebulkofanthropogenicCOemissionsisfromthetransportsectorincluding58to85percentinOECDcountries,above90percentintheMiddleEast,andbetween50and60percentinthetropicalAsiancountries.

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Table4.6TransportSectorContributiontoAirPollutantEmissionsinSelectedCountriesPercentageattributabletotransport

Country Year CO HC NOx SOxOECD

Canada 1985 66 40 64 3USA 1988 67 33a 41 4Austria 1986 58 87 72Finland 1980 80 60 50France 1990 76 69a 48 21Germany 1986 74 52 61 5Greece 1985 32 55 3Ireland 1983 81 55 33 4Italy 1985 82 56 43 7Netherlands 1987 80 87 59 7Switzerland 1984 73 27 74 6U.K. 1985 75 40 48 3

EasternEuropeHungary 1987 99 39 2Poland 1988 40 37 33 3U.S.S.R 1988 66 40 29Estonia 1989b 73 56 1

MiddleEastandAsiaIsrael 1988 99 100 52 4Kuwait 1987 96 76 26 0.1SouthKorea 1987b 25 57 85 8Taiwan 1988b 46 53 50 14Malaysia 1988b 50 95 36 1Thailand 1982b 60 46 23 15

=notavailable.Note:ForamoredetailedlookatthetrendinemissionsandthecontributionoftransporttopollutantemissionsseeFaiz(1993):170-71.PM=particulatematter.aVolatileorganiccompounds,excludingmethane.bPercentageattributabletotransportappliesonlytomotorvehicles.

Source:Faiz(1993).

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HydrocarbonemissionsfromthetransportsectorinOECDcountriesrangefrom30to87percent,andinnon-OECDcountriesfrom37to100percent.Thedeveloping-countryshareissomewhathigher(46to100percent)becausethehigheraveragetemperaturesinmanydevelopingcountriesincreasetheamountofevaporativeemissions.

NOxemissionsfromthetransportsectorareapproximatelythesameinbothOECDandnon-OECDcountries.WiththeexceptionoftheUnitedStatesandCanada,NOxemissionsincreasedduringthe1980sinbothdevelopingandindustrializedcountries.

Thetransportsector'sroleinSOxemissionsinOECDandEasternEuropeancountriesis,withtheexceptionofFrance,generallylowbecauseofthelowsulfurcontentoffuelintheseregions.SOxemissionsarehigherindevelopingcountriesbecauseofthehighersulfurcontentoffuelandgreateruseofdieselfuelinpassengertransport.(Sulfurcontentisinexcessof0.6percentbyweightindevelopingcountriesand0.3percentbyweightintheUnitedStates.)TheproportionofSOxfromthetransportsectorinFranceishighbecauseofdrasticreductionsinSOxemissionsfromothersources,suchascoal-andoil-firedindustrialderivatives.(NuclearenergyisalargesourceofpowerinFrance.)

Thenatureofparticulatesandthevariationsinthemethodologiesusedtoobtainparticulateemissionsinventoriestendtomakecomparisonsofparticulatesamongcountriesunreliable.Ingeneral,thetransportsectorintheOECDcountriesemitsmoreparticulatematterthandothemorerigorouslycontrolledstationarysources(Faiz1993).

GasolineVehicles

Themid-1970ssawtheintroductionofmotorvehicleemissioncontrolprogramsinmajorindustrializedcountries,butthestandardsdiffered

fromcountrytocountry.Table4.7showsemissionstandardsforgasoline-poweredvehiclesintheUnitedStates,Japan,andtheEuropeanCommunity.UntilquiterecentlytheUnitedStateshadthemoststringentstandards.Switzerland'sbecameasstringentin1988,Sweden'sin1989.

ItislikelythattheemissionstandardsgiveninTable4.7willbeunachievableinmanydevelopingcountries,sincemeetingthemwouldrequiremodernizingvirtuallyallexistingvehicles.However,severaldevelopingcountrieshaveintroducedstringentemissionstandardsfornewvehiclesandsomewhatrelaxedrequirementsforin-usefleets.Forexample,Brazil,Mexico,Taiwan,Thailand,andKoreaareamongdevelopingcountriesthathaveadoptedbothmobile-andstationary-sourceemissionstandards.TheexhaustemissionstandardsadoptedbyBrazilforbothalcohol-andgasoline-poweredvehiclesandbyMexicoforgasoline-poweredvehiclesaregiveninTables4.8and4.9,respectively.Thesearereasonableemissionstandardsfordevelopingcountries.

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Table4.7ExhaustEmissionStandardsforGasoline-PoweredLight-DutyVehiclesinSelectedIndustrializedCountries(g/km)

Country Year CO HC NOxUnitedStatesa 1980 5.6 0.25 1.2

1992 2.1 0.25 0.6By1995 2.1 0.16 0.25By2003 2.1 0.08 0.125

Japanb* 1975 2.7 0.39 1.21978current 2.7 0.39 0.48

EECc,** ByJuly1992f 2.72# 0.97g,#AfterJanuary1993f

ByJuly1992f 3.16## 1.13g,##AfterJanuary1993f1996proposed 2.2 0.5g

Swedend After1988 2.1 0.25 0.620.76Australiae 1986 9.3 0.9 1.9Switzerlande 1987 9.3 0.9 1.2

1988 2.2 0.21 0.62Canadae 1987 2.1 0.25 0.62=notavailable.*Testprocedureusedwasthe10-modetestcycle;standardsgivencorrespondtomaximumlimits.**ThisisaConsolidatedDirective(91/441/EEC)givingemissionstandardsforallnewvehiclesbelow2.5metrictons,ofwhateverfuelandenginetype,boughtintheEC.(Particulatelimitsnotgivenastheyarenotapplicabletogasolinevehicles.)#Typeapprovallimits.##Conformityofproduction.Note:g/km=gramsperkilometer.Foreachpollutantatypeapprovallevelisdefinedfornewvehiclemodels,asisaconformityofproductionlevelagainstwhichasampleofvehiclesfromagivenproductionrunischecked.aMageandWalsh(1992).bWatkins(1991).cOECD/IEA(1993b):145-54.dEconomicCommissionforEurope(1991:35).eOECD(1988).fAllnewmodelsoflight-dutyvehiclesarerequiredtomeetthislimitbyJuly1992

fAllnewmodelsoflight-dutyvehiclesarerequiredtomeetthislimitbyJuly1992andallnewcarsafterJanuary1,1993.gHC+NOx.

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Table4.8Brazil'sEmissionStandardsforGasoline-andAlcohol-PoweredLight-DutyVehicles(g/km)

Typeofemission Year CO HC NOx RCHOExhaust 19891991 24.0 2.1 2.0

19921993 12.0 1.2 1.4 0.15March1994 12.0 1.2 1.4 0.15January1997 2.0 0.3 0.6 0.03

Evaporative 19891991 6.0(g/test)19921993 6.0(g/test)bMarch1994 6.0(g/test)bJanuary1997 6.0(g/test)b

=notavailable.Note:g/km=gramsperkilometer;g/test=gramspertest.aOnlyforalcohol-fueled,light-dutyvehicles.bExpressedaspropaneforgasohol,orcorrectedtoethanolforalcoholvehicles.Source:Walsh(1993c:4143).

Table4.9Mexico'sEmissionStandardsforGasoline-PoweredMotorVehicles(g/mile)Description HC CO

1989cars,notrucks 3.20 35.21990cars 2.88 28.8GVWupto6,012poundsa 3.20 35.2GVW6,013to6,614poundsb 4.80 56.01991cars 1.12 11.2GVWupto6,012poundsa 3.20 35.2GVW6,013to6,614poundsb 4.80 56.01992cars 1.12 11.2GVWupto6,012poundsa 3.20 35.2GVW6,013to6,614poundsb 3.20 35.21993cars 0.40 3.4GVWupto6,012poundsa 3.20 35.2GVW6,013to6,614poundsb 3.20 35.21994cars 0.40 3.4

GVWupto6,012poundsa 1.00 14.0GVW6,013to6,614poundsb 1.00 14.0

Note:GVW=Grossvehicleweight.aCommercialvehicles(e.g.,NissanvanandCombis).bLight-dutytrucks.Source:MageandWalsh(1992).

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Diesel-PoweredVehicles

Diesel-fueledmotorvehiclesareontheriseinmanydifferentpartsoftheworld.Sincemillionsofpeopleareexposeddailytodieselfumes,emissionstandardsfordieselvehiclesareimperative.Theindustrializedcountrieshaveattemptedtocontroldieselparticulatesbysettingrisingstandards,amongothermeasures.Tables4.10and4.11presenttheexhaustemissionstandardsforlight-andheavy-dutydieselvehicles,respectively,intheUnitedStates.Table4.12givesthestandardsforheavy-dutydieselvehiclesinEurope.

StandardsforSulfurContent.In1990theU.S.EnvironmentalProtectionAgencyannouncedplanstoreducethesulfurcontentofdieselfuelsby80percentfrom0.25wt-%to0.05wt-%effectiveOctober1,1993(''EPAIssues1993andLater:DieselSulfurRegulations"1990).Mexico,aspartofanongoingprogram,loweredthesulfurcontentofdieselfuelto0.1wt-%.AlthoughTaiwan'sdieselfuelpresentlycontains0.5wt-%ofsulfur,itproposestoreducesulfurcontentto0.3wt-%by1993andtotheU.S.standardof0.05wt-%by1997.Brazil'sdieselfuelcurrentlyhasasulfurcontentofabout1wt-%,butattemptsarebeingmadetointroducea0.5wt-%sulfurdieselfuelincitybuses(Walsh1993a:9,1617).Ageneraltrendtowardloweringthesulfurcontentinfuelisapparent,atleastincountrieswherethisisfinanciallyandtechnologicallyfeasible.Reductionofsulfurinfuelwillreducedieselexhaustemissions'contributiontotheproductionofsulfurdioxide.

LimitsonParticulateEmissions.Controlofparticulatesfromdieselfuelhasgainedincreasedimportanceovertime.Thefirstdiesel-fuelparticulatestandardswereestablishedbytheEPAin19800.6g/mileforallcarsandlight-dutytruckscommencingwithmodelyear1982.Thestandardwasloweredto0.2g/mileforcarsin1985andto0.26g/mileforlight-dutytrucksbeginningin1987(Walsh1993a:2).

CanadaadoptedtheU.S.dieselparticulatestandardsof0.20(0.13g/km)and0.26g/mile(0.16g/km)forautomobilesandlight-dutytrucks,respectively,in1985.SwedenalsoadoptedtheU.S.standardforparticulateemissionsforautomobiles.

InAustriathemaximumpermissiblelimitforparticulateemissionsis0.6g/mile(0.38g/km),butbothAustriaandSwitzerlandareexpectedtoadoptU.S.light-dutytruckstandardsinthenearfuture(Walsh1992d).TheEuropeanCommunity(EC)decidedinJune1991toadoptstandardsforallnewmodelsofbothgasolineanddiesellight-dutyvehicles,commencinginJuly1992,ofnomorethan4.35g/mile(2.72g/km)ofCOandamaximum1.55g/mile(0.97g/km)ofvolatileorganiccompounds(VOCs)andNOxcombined,andfordieselvehiclesamaximumemissionof0.22g/mile(0.14g/km)ofparticulates.ConformityofProductionlimitsareasfollows:CO5.06g/mile(3.16g/km),VOCandNOxcombined1.81g/mile(1.13g/km),andfordieselvehiclesaparticulatelimitof0.29g/mile(0.18g/km)(OECD/IEA1993b:149).

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Table4.10U.S.EmissionStandardsforLight-DutyDieselVehicles(g/mile)Modelyear VOC CO NOx Particulates

1981 0.41 7.0 2.019821986 0.41 7.0 2.0 0.619871994 0.41 7.0 2.0 0.219941996limitstobephasedin:

First50,000miles 0.25 3.4 0.4 0.08Second50,000miles 0.31 4.2 0.6 0.1

From2004 0.125 1.7 0.2 0.08Note:g/mile=gramspermile.Light-dutyvehiclesincludecars,taxis,vans,andlighttrucks(lessthan3.5metrictonsinEuropeandlessthan3.9metrictonsintheUnitedStates).Source:OECD/IEA(1993a):136.

Table4.11U.S.EmissionStandardsforHeavy-DutyDieselVehicles(g/BHP-hr)Modelyear HC CO NOx Particulates

1983 1.3 15.5 10.7 0.61990 1.3 15.5 6.0 0.61991 1.3 15.5 5.0 0.251991(buses) 1.3 15.5 5.0 0.101994 1.3 15.5 5.0 0.101994(buses) 1.3 15.5 5.0 0.05a1998 1.3 15.5 4.0 0.1b2004 1.3 15.5 3.0 0.1cNote:Unitsareingramsperbrakehorsepower-hour.Heavy-dutyvehiclesincludegoodsvehiclesandbusesexceeding8,500pounds(3.9metrictons).aOr0.07if0.05g/BHP-hrprovesnotfeasible.bFederalproposal.cCaliforniaproposal.Source:OECD/IEA(1993c):119.

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Table4.12CurrentHeavy-DutyDieselPollutantLimitsinEurope(g/kWh)Country CO HC NOx Particulates

SwitzerlandStep1(October1989)andAustriaStep1(January1988)

8.4 2.1 14.4

SwitzerlandStep2(October1991)andAustriaStep2(October1991)

4.9 1.23 9.0 0.7

Sweden93MY(A-30)andNorway(October1993) 4.9 1.23 7.0 (0.35or0.40)

ECStep1(1992) 4.5 1.1 8.0 0.63(<85kW)

Typeapproval0.36(>85kW)

Conformityofproduction (4.9) (1.23) (9.0) (0.7)(<85kW)

(0.4)(>85kW)

SwitzerlandStep3 (4.9) (1.23) (9.0) (0.4)ECStep2(1995)(AlsolikelySwissStep4)

4.0 1.1 7.0 0.15

ECStep3(2000)orlater Newtestpossible

Note:g/kWh=gramperkilowatthour.Heavy-dutyvehiclesincludegoodsvehiclesandbusesofmorethan3.5metrictons.Source:Walsh(1992d).

TheU.S.CleanAirActandAmendments

TheU.S.CleanAirActof1970,asamended,establishedemissionstandardsfordifferenttypesofvehiclesforCO,HC,andNOx;authorizedtheEPAtoestablishregulationsforfuelqualityforconventionalandalternativefuels,performancestandardsforvehiclesusingalternativefuels,andemissionstandardsforvehiclesnotregulatedbytheAct;andauthorizedtheEPAtoestablishNationalAmbientAirQualityStandards(NAAQS)fordesignatedpollutants(CO,NOx,ozone,particulatematter,SOx,andlead)thatwouldensuretheprotectionandenhancementofthecountry'sairresources.

ensuretheprotectionandenhancementofthecountry'sairresources.

TheCleanAirActAmendments(CAAA)of1990tightenedrevisionstothe1970Act(CleanFuelsLegislationDirectory1994)bytighteningpollutioncontrolmeasuresincitiesthatwerenotcomplyingwithfederalairqualitystandards,makingchangesinfuelspecifications,andendorsingtheuseofalternativefuelsinareaswiththeworstairqualityproblems(seeTable4.13forasummaryofthefuelprovisionsoftheCAAAof1990).Morestringenttailpipeemissionstandardswereestablished,anduseofcleanerfuelsingasolineanddiesel-poweredvehicleswasstipulated.Theamendmentsrequiredbasicreformulationofpetroleumfuels,reductionofsulfurlevelsindieseloil,andlimitationsonbenzeneandaromaticsingasoline,loweringofvaporpressure,andadditionofoxygenates.TheEPAissuescleanfuelrequirementsandemissionsstandardsunderTitleIIoftheCAAA(CleanFuelsLegislationDirectory1994).

Table4.13U.S.FuelSpecifications19922000,BasedonU.S.CleanAirActAmendmentsof1990

Fuelsprovision Effectivedate

Amendments

OxygencontentinCOnonattainmentareas(moderateandserious)

11/1/92 2.7wt-%minimumaverageoxygencontentfornolessthanfourwintermonths

IffederalairqualitystandardforCOhasnotbeenachievedbyaspecifiedattainmentdate,minimumoxygencontentwillincreaseto3.1wt-%

Oxygencontentinozonenonattainmentareas

1/195 2.0wt-%minimumaverage

Aromaticscontent 1/1/95 25vol-%maximumBenzene 1/1/95 1.0vol-%maximumLead 1/1/95 Prohibitedtomanufacture

1/1/96 Illegaltosellgasolinewithleadorleadadditivesforhighwayuse

Additives 1/1/95 Required,fordepositcontrolAirtoxics 1/1/95 15%reduction

2000 20%reductionVOCs 1/1/95 15%reduction

2000 25%reduction;ifEPAdecidesitistoocostlyorisnotfeasible,then20%reduction

NOx NoincreaseinNOxOzonenonattainmentareasaffectedbyrequirement

1/1/95 Ninecities(with1989ozonedesignvalueof0.18ppmorgreater)with"opt-in"provisionforothermoderateorseriousozonenonattainmentareas.

Reidvaporpressure(Rvp)Summer1992

9.0psiforallgasoline

Summer1992

10psiforgasolinewitha10%orgreaterethanolcontent,whichisgranteda1.0psiwaiverofRvpstandard.

Sulfur(diesel) 10/1/93 0.05wt-%maximumCetaneindex(diesel) 10/1/93 40minimumNote:VOCs=volatileorganiccompounds.Forimplementationpurposes,the1990CleanAirActAmendmentsdefineanareaaseithera"nonattainmentarea"oran"attainment

AirActAmendmentsdefineanareaaseithera"nonattainmentarea"oran"attainmentarea."AreasinviolationoftheNationalAmbientAirQualityStandards(NAAQS)forozoneorcarbonmonoxideorparticulateemissionsbecome"nonattainmentareas."Source:AdaptedfromOECD/IEA(1993a:138)andCleanFuelsLegislationDirectory(1994:4144).

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The1990legislationcallsfora2.7wt-%minimumaverageoxygencontentfornolessthanfourwintermonthsinallgasolinessoldinbothmoderateandseriousCOnonattainmentareas,risingto3.1wt-%inallCOnonattainmentareasifthestandardisnotmet.A2.0wt-%minimumaverageoxygencontentisrequiredforthenineworstozonenonattainmentareasbythebeginningof1995.Citieswithalessseriousproblemmaychoosetoadopttherequirementsthen.Benzenecontentislimitedto1.0vol-%andaromaticsto25vol-%.Allheavymetaladditivesareprohibited;leadandmanganesearementionedspecifically.

MostindustrializedcountrieslooktotheUnitedStatesasaleaderinestablishingstandardsforairqualityandcontrolofharmfulemissions.OtherOECDcountrieseventuallyadoptedtheU.S.airqualitystandardsestablishedin1970.ThismayindicatethatOECDcountrieswilladoptthe1990changesaswell.However,futuregasolineanddieselspecificationsandformulationsnowconsideredessentialintheindustrializedcountrieswillrequireamajorrestructuringofrefineriesinthosecountries.Ifthedevelopingcountriesaretoadoptthesamestandards,evenatareducedpace,similarmajorinvestmentsinrefineriesmayberequired.

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5ValuationoftheBenefitsofMitigatingAirPollutionDevelopingcountriesmustmakechoicesinallocatingresourcestomeetmanypriorities,includinghealth,education,reductionofpoverty,andprotectionoftheenvironment.InThailand,Mexico,Taiwan,Indonesia,andKorea,recentandrapideconomicgrowthhasprovidedtheresourcesneededtoimproveenvironmentalquality.Inmanyoftheleast-developedcountries,however,suchresourcesmaynotbesoavailable.Nonetheless,countriesthatproducemoregoodsandservicesanduseincreasingamountsofenergyintransportationareboundtoproducemorepollutionandwillhavetotakeearlyanddecisive,ifnotcomprehensive,stepstoaddresstheproblemorriskcontinuingdegradationoftheenvironment.Forthesecountries,implementingthenecessaryenvironmentalmeasuresmayrequiretheassistanceofinternationalagencies.

Onewaycountrieswhatevertheirstageorrateofdevelopmentcanjustifyandplanforenvironmentalprotectionisbymakingeffortstoquantifyfactorsaffectingenvironmentalqualityandestimatetheireconomiceffects.Thisisacomplexexercise,inasmuchasthecostsareprimarilyintheformofadversehealthimpactsanddonotlendthemselvesreadilytoquantification,andadequateenvironmentaldataareoftenlackingindevelopingcountries.Moreover,applicationofvaluationmethodologiesrequireshighlyspecializedskills.Mostdevelopingcountrieswilllikelyfindthetasksofevaluationandameliorationdauntingbothinfinancialandmanagerialterms.Thismakesitallthemoreimportanttomakerealisticassessmentsofenvironmentalproblemsandtodevelopaffordableprogramsthatcanbecarriedoutinorderoftheirnetbenefits.

Thisreportdoesnotattempttosetenvironmentalorsocialprioritiesfordevelopingcountries.Suchanexercisemustbebasedonmoreextensivestudiesandinanycasewillhavetooriginatewithinthespecificcountriesthemselves.Instead,thechapteraddressesoneofthefoundationsofairqualitymanagementevaluatingthebenefitsofmitigatingairpollutionassociatedwithincreasesinindustrialoutput,energyuse,andtransportation.Includedareamethodologyforestimatingenvironmentalbenefitsaccruingfromthereductionofvariouspollutantsanddiscussionofthelimitsofcurrentenvironmentalprotectionmethods.Toillustratethebasisforvaluingbenefits,the

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chaptersummarizessomerecentWorldBankresearchonthepotentialhealthbenefitsofimprovingambientairqualityinBangkok,Thailand.

AHealth-BenefitsModel

Reductionsinconcentrationsofambientairpollutantswillreduceexposureofthepopulationtopollutantsandthusreduceacuteandchronicillness,thecostsofmedicalservices,andprematuremortality.Theywillalsoincreaseproductivityandimprovethequalityoflife.Asocietythatbenefitsfromimprovementsinairqualitywillnormallybeexpectedtopayforthesebenefits,butfullcostrecoveryisnotfeasibleformostdevelopingcountries.Forexample,althoughareductionofsulfuremissionsfromdieseloilusedinpublictransportwouldhavemajorbenefits,thecostisveryhigh,andthelowincomepeoplewhoarethelargestusersofpublictransportcouldnotabsorbitallifitwerepassedontothemintheformofincreasedpassengerfares.Eveninthedevelopedcountries,increasesinthecostofaproductorservicewillultimatelyhaveanimpactoneconomicactivity.Hence,itisimperativethatappropriatecriteriaareadoptedtomeasurethehealthbenefitsofreducingvariouspollutantsandthatairpollutionmanagementprogramsaredevelopedinacost-effectivemanner.

Twocomplementaryapproachesaregenerallyusedtoestimatetheimpactsofpollutiononhealth.Wherewell-establishedrelationshipsareavailablethatlinkconcentrations(orexposures)tohealthimpacts(dose-responseorconcentration-responsefunctions),aswithairpollutantssuchasSPM,lead,SO2,andozone,thesefactorscanbecombinedwithdataonambientairqualityoremissionstoderiveestimatesofmortalityandmorbidity(Ostro1994;Krupnickandothers1992).Inthiscase,ahealth-benefitsmodelisusedtocalculatetheeconomicvalueoftheresultingmortalityandmorbidityeffects.

Wheredose-responserelationshipsarenotwellestablished,aswithCO,onepossibleapproachistoestimatethepopulationatrisk.

Thehealth-benefitsmodelisbasedonthedamage-functionapproachtoestimatingbenefits.Beginningwithbaselinedataandprojectedchangesintheconcentrationofspecificpollutants,dose-responsefunctionsfromepidemiologicalandpopulationdataareusedincalculatingchangesinavarietyofhealthendpoints.Theeconomicvalueofthesebenefitsisthenestimated,basedonhealthbenefitsfrompublisheddata.Themodelaggregatesthebenefitsassociatedwithprojectedchangesinpollutantconcentrations.Eachofthesecalculationsisperformedusingstatisticalandjudgmentalconfidenceintervalsonthecoefficientsofthedose-responseandvaluationfunctions.Theresultingrangesofimpactsandbenefitsarepropagatedusingthecrudebutcommonapproachofmultiplying"low"healthimpactestimatesby"low"values,"high"impactsby''high"values,and"expected"impactsby"expected"or"best"values.

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TheCaseofThailand

SummaryDataandKeyFindings

Applicationofthehealth-benefitsmodelisillustratedina1994WorldBankstudyonThailandthatanalyzesthepotentialhealthimpactsofa20percentreductionofambientconcentrationsofvariouspollutants.Tables5.1through5.4showtherangeandbestestimatesofthehealthimpactsassociatedwithsuchachangeinBangkok.Table5.5summarizestherangeofhealthbenefitsofsuchareduction.

Table5.1Bangkok:EstimatedImpactsonMorbidityandMortalityof20PercentReductioninAmbientConcentrationsofSPM

ReductioninnumberofcasesperyearHealthimpacts Low Mid High

Restrictedactivitydays 3,300,000 5,330,000 8,370,000Emergencyroomvisits 3,120 34,600Asthmaattacks 322,000 5,800,000 51,300,000Chronicbronchitisinchildren 863 78,600 156,000Chroniccoughinchildren 537 90,700 181,000Respiratoryhospitaladmissions 3,450 14,900Respiratorysymptomsdays 159,000,000 200,000,000 251,000,000Mortalityreductions

SchwartzandDockery(1992a)-SPM 152 405SchwartzandDockery(1992b)-SPM 459 761

Note:SPM=suspendedparticulatematter.Source:1994WorldBankdata.

Table5.2Bangkok:EstimatedImpactsonMorbidityandMortalityof20PercentReductioninAmbientConcentrationsofLead

ReductioninnumberofcasesperyearHealthimpacts Low Mid High

ReductioninIQpointsinchildren 16,000 26,700Hypertensioninadultmales Nonegiven 9,500 NonegivenCoronaryheartdiseaseeventin10year Nonegiven 677 Nonegiven

MortalityreductionsNeonatalmortality Nonegiven 4.27 NonegivenAdultmalemortality(in12years) Nonegiven 846 Nonegiven

Source:1994Worldbankdata.

Table5.3Bangkok:EstimatedImpactsonMorbidityof20PercentReductioninAmbientConcentrationsofSO2

ReductioninnumberofcasesperyearHealthimpacts Low Mid High

Coughingbychildren 15,900 152,000 288,000Chestdiscomfortinadults 6,630 169,000 331,000Source:1994WorldBankdata.

Table5.4Bangkok:EstimatedImpactsonMorbidityof20PercentReductioninAmbientConcentrationsofO3

ReductioninnumberofcasesperyearHealthimpacts Low Mid High

Minorrespiratory-relatedrestrictedactivitydays 32,400 239,000 489,000Anysymptom-day 762,000 1,930,000 3,090,000Asthmaattacks 16,200 59,300 101,000Eyeirritationdays 1,790,000 2,430,000 3,070,000Coughingdays 436,000 1,060,000 1,700,000Coughincidents 5,110,000 8,830,000 13,000,000Shortnessofbreath 3,390,000 7,600,000 11,800,000Discomfortinchest 3,170,000 6,490,000 9,940,000Source:1994WorldBankdata.

Table5.5SummaryofHealthBenefitsof20PercentImprovementinAirQualityinBangkok

Pathway:impact Total($million) Healthbenefits(1989)percapita(s)Particulates:mortality 1381,315 18169Lead:mortality 302309 3940Lead:morbidity 68 0.81Sulfurdioxide:morbidity 0.2 <0.1Ozone:morbidity 936 15

TOTAL 7463,138 96402Source:1994WorldBankdata.

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Themodelsuggeststherangesofbenefitsfromreductionofdifferentairpollutants.Therangesindicatetheuncertaintiesinherentinsuchanexercise.Theestimatesareindicativeoftheorderofmagnitudeofexpectedbenefits,andthelowlevelsshowexpectedminimumbenefits.Yetdespitesuchlimitations,thestrikingfeatureoftheseestimatesisthatthehighestbenefitswouldcomefromreductionsinconcentrationsofSPMandlead.Thus,thelowestimatesofbenefitsfromreducingleadexceedthehighbenefitsofreducingambientSO2orozone.ThedisparityinbenefitsreflectsthemuchhigherambientlevelsofparticulatesandleadrelativetoSO2andozone.Moreover,exposuretothesehighlevelsofSPMandleadcausesdeath,makingreductionofthesepollutantsfarmorevaluablethanreductionsoftheillnessesthatresultfromexposuretoSO2orozone.

LimitationsoftheModel

Threefeaturesofthemodel,however,maylimititsvalue.Thesepertaintotheprocessoftransferringthedose-responseandvaluationfunctionsdevelopedinonecountrytoanother.

ProblemsinTransferabilityofDose-ResponseFunctionsfromDevelopedtoDevelopingCountries.First,althoughthedose-responsefunctionsarerecentandemploystate-of-the-artstatisticalandsurveytechniques,theywereestimatedforspecificregionsoftheUnitedStates.ThemostseriousdifficultyinapplyingthemtoBangkokisthattheepidemiologicalstudiesonwhichtheyarebasedalsoinvolvedtheUnitedStates.Thesestudieslinkchangesinambientconcentrationstohealtheffects,withanassumedlinkbetweentheamountofapollutantactuallyinhaledbyapersonduringagivenperiodanditsambientconcentration.Totheextentthatpeopleactuallybreathemorepollutedairperperiod(exposureordose)forgivenambientconcentrationsofpollutants,theseepidemiologicalstudiesunderestimatetherelationshipindevelopingcountries.Thatis,thereisgoodreasonto

believethatexposuretoairpollutantsinBangkokaswellasinthemetropolitanareasofmostdevelopingcountriesishigherbecausepeoplespendagreateramountoftimeonthesidewalksandstreetsandinopenvehiclesthaninU.S.cities(particularlyLosAngeles,thesiteofanumberoftheepidemiologicalstudies).Furthermore,morepeopleindevelopingcountriesliveclosertotrafficarteries.Finally,inferiorhousingandlessuseofairconditioningmeanthatthediffusionofairfromoutdoorstoindoorsmaybegreaterincitieslikeBangkok.

Theproblemsinextrapolatingdose-responsefunctionsarealsoexacerbatedbythepotentialforinaccuracyinestimatingthepredictedhealthimpactscausedbythefactthattheaveragepersoninBangkokislesshealthythantheaveragepersonintheUnitedStates.Lesshealthypersonsaremoresusceptibletopollution-induceddiseases,soadose-responsefunctionforacitylikeBangkokmaybesignificantlysteeperthanonefortheUnitedStates.

ProblemsinBalancingInformationfromLaboratoryandEpidemiologicalResearch.Asecondlimitationisthattheseestimatesexcludethehealthimpactsofairpollutionthathavebeenfoundinlaboratoryandtoxicologicalresearchbuthaveyettobe

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reproducedinepidemiologicalstudies.Note,forexample,thattheeffectsofSO2onhealtharerelativelysmall.ThisisaconsequenceoftheprevailingviewthatparticulateeffectssurpassthoseofSO2wheneverthetwopollutantsaretreatedtogetherinstatisticalanalysis.TheeffectsofSO2throughitstransformationtoacidaerosolscannotberuledout,however,becausethesesulfatesarecountedasparticulates.Thus,somefractionofthebenefitsfromreducingparticulatesinBangkokcouldprobablybeattributedtoreductionsinSO2throughassociatedreductionsinsulfates.

SkewingofDatabyLimitsinSampling.Third,itmaybequestionedaswellwhetherthequalityofthedataresultsinanoverestimationofhealtheffects.Themonitorsusedtogatherdatawerelocatedindensedowntownareasandthereforemayoverestimateeffectsonpeoplewholiveandworkinoutlyingareas.ThismaybeparticularlytrueforleadandSPM,butlesssignificantforozoneconcentrations,whichdispersemorebroadly.Arelatedissueiswork-lossdays,whichagainwerederivedfromU.S.data.AbsenteeratesaregenerallythoughttobelowerinThailandthanintheUnitedStatesbecauseofgreaterpenaltiesimposedonworkersforabsenteeism,soworkdayslostthereforemightbefewerinBangkok.

Notwithstandingitsshortcomings,themodeldoesofferarational,asopposedtoasubjective,basisforevaluatinghealthbenefits.Ideally,ifnewbenefitsmodelsweredevelopedthatmorecloselysimulatedtheconditionsindevelopingcountries,amorerealisticandpreciseassessmentofbenefitscouldbemade.Thedevelopmentofcountryorregion-specificmodelswouldentailsubstantialtimeandcosts.Withcarefuladjustmentoftheinputdata,however,thecurrentmodelcouldbeavaluablebasisfordesigninganairpollutionmanagementprogram.

RelevancetoDevelopingCountries

Themethodologyandthehealth-benefitsmodeldiscussedinthischapterareapplicabletoallcountries,providednecessarychangesaremadeintherelevantcoefficients.ThehealthbenefitsintheThailandstudyassumedareductionof20percentinambientpollutionconcentrations,irrespectiveofwhethertheseconcentrationsexceededpermissiblelimits.Fordevelopingcountries,thepermissibleconcentrationlevelsestablishedbytheWHOaresound.Controlstrategieswouldbedesignedtoaddresspollutantsthatarealreadyatornearthesafelimitsandlikelytoexceedtheselimitsintheforeseeablefuture.

Beforeamajorairpollutionmanagementprogramisputinplace,thevalueofitsbenefitsmustbeassessed,asinthecasestudyofThailand.However,dataonambientpollutionconcentrationswillhavetobeextrapolatedtocoveraperiodofatleast15years,usingamodellinkinggrowthinemissionswithambientairquality.Epidemiologicaldatacoveringaslongaperiodaspossibleshouldbeusedtoidentifymajororchronichealthproblems.Valuationofbenefitsmusttakecognizanceofallthesefactors.

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6OptionsforMitigatingAirPollutionPreviouschaptershaveexaminedtheenvironmentalandhealthimplicationsofvariousairpollutantsandthebenefitsofreducingambientairpollution.Thediscussionhasstressedthatevaluationmodelsmusttakecarefulaccountofthedifferencesintheeconomicandepidemiologicalcontextsofdevelopedanddevelopingcountries.

Similarspecificityisnecessaryinselectingoptionsformitigatingairpollutionbecauseofthevaryingprofilesofpollutionsourcesindevelopedaswellasindevelopingcountries.Inbothdevelopedanddevelopingcountries,themainsourceofurbanairpollutionisthetransportsector.Insomedevelopingcountries,however,industryisalsoakeyurbanairpolluter.Thedifferenceisattributabletothefactthatwhereasdevelopedcountrieshaveforsometimetendedtolocateindustrialplantsawayfromthecentersofcities,developingcountrieshaveallowedandevenencouragedindustriestoclusteraroundpopulouspolitical,commercial,andbankingcenters.Forexample,theBangkokmetropolitanregionaloneencompassessome73percentofThailand'smanufacturingindustries,contributingmorethan50percentofgrossdomesticproduct(GDP).Similarly,largecitiesinMexico,thePhilippines,India,Indonesia,andKoreaallcontainhighconcentrationsofheavyindustries.Hence,mitigatingairpollutioninthecitiesofmanydevelopingcountrieswillrequirelimitingemissionsfrombothstationaryandmobilesourcestolevelsthatwouldnotcollectivelypushconcentrationsofpollutantspastsafelimits.Choosinganyspecificstrategywillrequireabasicappreciationoftheoptionsforreducingbothstationaryandmobilesourceemissions.

OptionsforReducingStationary-SourceEmissions

Developingcountriesalmostuniversallyperceiveindustrializationasthekeytoeconomicprosperity.Duringthelastdecadeinparticular,theyhaveprovidedliberaltaxincentivesfornewindustriesandinsomecasesdismantledurbanandenvironmentalregulationsthatwereconsideredasimpedimentstotheflowofinvestmentcapital.Thebroadeffectofsuchpolicieshasbeentodrawhigh-pollutingindustriesfromdevelopedtodevelopingcountriesand,concomitantly,toacceleratethedeteriorationoftheambientairqualityofmanycitiesinthedevelopingworld.Ifthistrendistobearrested,developing

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countrieswillneedtoidentifyandpursueoptionsforreducingemissionsfromexisting,relocated,andnewindustries.Someofthemoreattractiveoptionsarediscussedbelow.

SwitchingtoNaturalGas

Switchingtocleanerfuelsisoneofthemostcost-effectivestrategiesforreducingemissions,particularlyofSO2andCO2.Thecleanfuelofchoiceisnaturalgas.Korea,whichhasnoreserves,importsnaturalgasforusebyindustriesandinpowerplants.Naturalgascontainsvirtuallynosulfur,andburningitalsoproducesfarlessNOxthancoalorfueloil.Sincenaturalgashasahigherhydrogentocarbonratio,itproducesfarlessCO2,agreenhousegas,thaneithercoalorfueloil.Acombined-cyclepowerplantusingnaturalgasproduces55percentlessCO2thanacoal-firedpowerplantperunitofelectricityproduced.

UsingLow-SulfurCoal

Low-sulfurcoalisanotherfueloptionfordevelopingcountriesdespiteitsenvironmentaldrawbackscomparedwithgas.Ifhigh-quality,low-sulfurcoalcanbeimportedatareasonableprice,newtechnologiessuchascoalwashing(whichcanreducethesulfurcontentofhigh-qualitycoalfrom50percentto20percent)maymakecoalaviableoption.Also,newcombustiontechnologiescanreduceNOxemissionsbyabout50percent.Useoffluidized-bedcombustionorintegrated-gasification/combined-cyclepowergenerationatnewplantshasalsoresultedinsubstantialSO2andNOxcontrol.

Scrubbingofstackgasesfromcoal-firedpowerplantsreducesbothSO2andNOxemissions.Thecostsarehigh,however,especiallyforretrofittingoldplantswithscrubbers.Anotherdrawbackofscrubbersisthattheyproducelargequantitiesofsludgeandlow-gradegypsumwastethatmustbedisposedof.Butscrubberscanremoveabout95percentoftheSO2andbetween70and90percentoftheNOx

producedbycoalcombustion(formoredetail,seeTavoulareasandCharpentier1994).

EncouragingandPracticingConservation

Energyconservationoptionsincludemodernizationofexistingplants,includinginstallationofwasteheatrecoveryequipmenttogeneratesteamorasprocessheat,andimprovementsinefficiency.Identifyingtheseoptionsandtheireconomicandenvironmentalbenefitsrequiresmajorstudiesofexistingfacilities,buttheinvestmentsarerelativelymodestandthebenefitssubstantial.

ExploitingAlternativeEnergySources

Alternativeenergyoptionsincludehydro,wind,solar-thermalandphotovoltaicpower,geothermal,nuclear,andhydrogen.Nuclearpowerandhydropowerarethemostcommonoptions.Manydevelopingcountrieshavedevelopedtheirhydropowerpotentialtoasubstantialextent.Useofnuclearpower,exceptinKorea,hasnotprogressedmuchbecauseofsafetyandenvironmentalconcernsaswellasthelargecapitalrequirements.Forcurrentdataonpromisingrenewableenergyoptions,seeAhmed(1994a).

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OptionsforReducingMobile-SourceEmissions

Optionsforreducingairpollutionfrommobilesourcesincludereplacingoldvehicles,maintainingin-usevehiclesmoreeffectively,usingalternativecleanerfuels,reformulatingfuels,improvingtrafficmanagement,expandingmasstransitsystems,andimprovingroadandhighwaycapacity.Theseoptionsareexploredbrieflybelow.

ReformulatingFuels

Substantialworkhasbeendoneintheindustrializedcountriesonthereformulationoftransportfuelstoreducepollutantemissions.Someofthemoreindustriallyadvanceddevelopingcountrieshavealsoembarkedonsuchprogramsdespitetheircapital-intensity.Abriefintroductiontofuelsreformulationfollows.

Gasoline.Themainpollutantsemanatingfromgasolinearelead,aromatics,benzene,carbonmonoxide,andhydrocarbons.WhencatalyticconvertersweredevisedtoreduceemissionsofCO,HCandNOx,itthenbecamenecessarytoremoveleadfromgasolineaswellbecauseleaddeactivatesthecatalystintheconverter.Theobjectatthattimewasnottoprotecthumanhealth;theharmfuleffectsofleadbecameanissueonlylater.Inaninitialefforttocompensatefortheoctanelosscausedbytheremovaloflead,U.S.refiners,inparticular,increasednaphthareformingcapacityasawaytoincreasehigh-octanearomaticsandbenzenecontentofgasoline.Then,whentheU.S.EPArestrictedthearomaticsandbenzenecontentofgasoline,refinershadtomakeadditionallargeinvestmentstocompensatefortheconsequentlossinoctane.

Currently,severaltechnologicaloptionsareavailabletocompensateforleadloss.Ifreformingaloneisinadequate,isomerizationoralkylationprocessescanbeused.SomeU.S.citiesthosedesignatedasCOorozonenonattainmentareasarenowrequiredduringthewinter

monthstoaddoxygenatestogasoline;thesehelptocompletethecombustionprocessandboostoctane.Methyltertiarybutylether(MTBE)istheoxygenateofchoice.

Ingeneral,developingcountriesconsumerelativelysmallquantitiesofgasoline,andhencethetotalamountofleadreleasedisalsolow.Regulationsmandatingremovalofleadthusmaynotbeofhighpriorityinsuchcontexts,particularlybecausetheinvestmentsneededtoreformulategasolinetocompensateforleadlossarehigh.Itmustberemembered,however,thatleadcanhaveseriouseffectsonhumanhealth.Thus,anydecisionregardingthepermissiblelevelofleadmustbemadeaftercarefulevaluationofthelikelyimpactofchange.Ifthereisanyevidencethatleadisaproblem,itsremovalshouldhavethehighestpriority.

Diesel.Mostdevelopingcountries,areheavyconsumersofdieseloil.ReformulatingdieseloilbyreducingitssulfurcontentwilldecreasetheemissionsofSO2andconsequentlyofsulfatesthatcontributetoelevatedconcentrationsofSPM.Inaddition,reductionintherefiningprocessoftheheavierhydrocarbonfractionsindieseloilbyreducingthetemperatureatwhich90volume-percentofthedieseloilisdistilled(therebyeliminatingagreaterproportionoftheSPM-formingdieseloilcomponents)will

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decreasetheformationofSPM10micronsorlessindiameter.Thecostofreformulatingdieseloilishigh,butbecausedemandfordieseloilishighandtheambientSPMconcentrationsarealsohigh,reformulationofdieseloilwilllikelymerithigherpriorityindevelopingcountriesthanreformulationofgasoline.

UsingAlternativeFuels

Liquefiedpetroleumgas(LPG)andcompressednaturalgas(CNG),whereavailable,canbecost-effectiveandenvironmentallybeneficialoptionsformanydevelopingcountries.However,theiradoptionastransportationfuelshasbeenslow,primarilybecauseoftheirlimitedavailabilitycomparedwithgasolineanddieseloil.

LimitingVehicleEmissions

Twootheroptionsareend-of-tailpipecontrols,suchascatalyticconvertersthatreduceexhaustemissions,andvehicleemissionstandards:

Catalyticconverters.Thetwotypesofcatalyticconverterscommonlyinuseareoxidationortwo-waycatalysts,whichreduceCOandHCemissions,andoxidation/reductionthree-waycatalyststhatcontrolNOxemissionsaswell.Formanydevelopingcountriescatalyticconvertersarenotahighpriority.Theycanaddabout$600tothecostofamediumsizecar(whichisabout3to5percentofthepriceofsuchavehicle)andsubstantiallyincreasethecostoflargervehicles.

Emissionstandards.ExperienceinOECDcountrieshasshownthatemissionstandards,ifenforced,cansignificantlyreduceairpollution.Effectiveinspectionandmaintenanceproceduresmustalsobeestablishedandimplemented.Thisisdifficultformostdevelopingcountries,otherthanfornewvehicles.Suchstandards,however,areimperativeforpublictransitvehicles.

ImprovingRoadInfrastructure

Congestedurbanroadsaresignificantsourcesofurbanairpollutioninallcountriesparticularlyduringpeakhours,whentrafficslowstoacrawl.Yetdevelopingcountriesinparticularoftenfindthatimprovingtheirroadinfrastructuretorelievetheproblemisnearlyimpossiblebecausetheirmetropolitanareashaveoftenexpandedsohaphazardlyastomakesignificantroadcapacityimprovementsalogisticandeconomicnightmare.Improvingroadinfrastructureisalsocostlybothintermsofcapitalrequirementsandtimetakentoimplementprojects,butwhenitispossible,itshouldtakeprecedenceoverothercapital-intensiveoptions.

EnhancingTrafficManagement

Alesscostlyapproachtorelievingtrafficcongestionisbyenhancingtrafficmanagement.Theurbanareasofdevelopingcountriesareplaguedbylargenumbersofvehiclesoninadequateroads,lackofsufficientparkingfacilities,undisciplineddrivers,frequentvehiclebreakdowns,andpoorlydesignedtrafficmanagementplans.Improvedpracticesformanagingtrafficcouldreducecongestionsignificantlyindeveloping

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countries.Animprovedplancouldincludesuchincentivesanddisincentivesasrestrictinguseofmainarteries,encouragingcarpooling,providingincentivestousepublictransport,improvingpublictransitsystemsorestablishingnewones,taxingcarsenteringcitylimits,andimposingsteeperparkingfees.

Disincentivessuchastaxationandincreasedvehicleorparkingfeesarelikelytobeunpopular.Therefore,majorpublicrelationseffortsmayberequiredtoeducatepeopleabouttheconsequencesoftrafficcongestionandairpollution.Withoutatrafficmanagementstrategy,developingcountrieswillseecontinuedincreasesinmotorvehicleusenegateairqualitygainsfromotherprograms.Trafficmanagementandroadimprovementsthusshouldbestudiedsimultaneously,andbothshouldhavehighpriorityinanystrategytoreduceairpollution.

DevelopingMassTransit

Masstransitsystemsarehighlycapitalintensive,andtheyareunlikelytoyieldaprofitunlesstheirconstructionandoperationaresubsidizedbythestate.Arecentstudyof20masstransitsystemsimplementedinrecentyearsindevelopingcountriesfoundthatnoneofthemwasprofitableinpurelyeconomicterms(Allportandothers1990).However,hadhealthbenefitsbeenfactoredintothisassessment,thesystemswouldlikelyhaveshownaneteconomicbenefit.Carefulproposalevaluationthatincludesthehealthbenefitscouldthereforeprovidejustificationforneededstatesubsidies.

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7TowardanAirQualityManagementProgramAsthisreporthasargued,theimportanceofmaintainingambientairqualityatacceptablelevelscannotbeoveremphasized.Thereporthasdiscussedthesourcesandcausesofdifferentpollutants,thespecificimpactofemissionsonambientconcentrationsofairpollutants,andtheresultingadversehealthandenvironmentalimpacts.Theneedtomitigatethedetrimentaleffectsofpollutantsisbeyonddispute.Yetbecausetheeffectsofabatementmeasuresoftentakesometimetobecomeevident,theircostsandbenefitsareseldomfullyappreciated.Theresultisfrequentlyapolicyof''benign"inactionthatenduresuntilpollutionbecomesunbearableandirreversible.Thathashappenedinmanycities,perhapsmostnotablyinMexicoCityandBangkok.Unfortunatelyfordevelopingcountries,theideahasbecomeprevalentthatattentiontoenvironmentalmattersmusttakeabackseattoimprovedeconomicconditions.ArecentarticleinTheEconomist("AllthatGas"1994),forexample,suggestedthatincomesmustreachanannualthresholdofUS$5,000percapitabeforeairqualityandenvironmentalissuesbegintoattractattentionandconcern.Thisnotionneednotandshouldnotbetakenasinevitable.

Thischapteroutlinessomeessentialstepsneededtodevelopacost-effectiveandtimelyairqualitymanagementprogram.Manyofthedetailsofsuchprogramsmustbedecidedanddevelopedatthenationallevelineachcountryandcannotbedetailedhere.Butanumberofvitalcommonrequirementscanbeidentified.Hence,thechapterfocusesondevelopmentofanappropriatelegalframework,adequateinstitutionalarrangements,andsufficientmanpowerresourcestoensureproperdesignandcontinuityofprograms.Italsostressestherequirementsforevaluatingtheentirerangeofoptionsand

forcreatingintegratedprograms.Clearly,concertedeffortsbytheinternationalcommunityarealsonecessarytosupporttheadaptationandimplementationofairqualitymanagementprogramsinthedevelopingworld.

LegalFrameworkandInstitutionalArrangements

Pollutionisdirectlyrelatedtoindustrialandeconomicactivity,andenvironmentalproblemswillincreasewithdevelopmentregardlessofacountry'spercapitaincomelevels.Themosteffectiveabatementprogramsthusmustproceedinvirtuallockstep

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withtheexpansionofindustrialandeconomicactivities.Putanotherway,itishardlyevertooearlyinthedevelopmentcycletoestablishenvironmentalstandards,regulatorymeasures,andframeworksforcomplianceandenforcement.Theneededstandardswillcoverambientairqualitylevelsaswellasemissionlevelsfrommobileandstationarysources.Atthesametime,inawell-conceivedand-executedprogram,economicactivitieswillbedesignedfromthegroundupsothatpollutionemissionsonaregionalornationalbasisdonotputthehealthofpeopleatriskorharmtheenvironmentwithinacountry'sboundariesorbeyondthem.

Ensuringahighlevelofairqualityplanning,management,andenforcementrequiresaneffectivelegalfoundationembodyingnationalvalues,laws,andprecedents.Inaddition,ifthegoalsofprovidingasafeandsalubriousenvironmentaretomovefromstatutetoreality,airqualityandpollutionmanagementeffortswillrequirestronginstitutions,competenttechnicalandmanagerialstaff,andcleargovernmentmandates.

Manydevelopingcountrieshavealreadybeguntodraftenvironmentallawsandtoestablishthenecessaryinstitutions.Yet,toooften,mitigationandcomplianceeffortsarefragmentedbyinternecinepoliticalandbureaucraticconflicts.Itisnotunusual,forexample,tofindthreeormoreinstitutionswithoverlappingjurisdictionsissuingcountervailingdirectivesandcompetingoverlimitedresources.Tosomeextent,theinvolvementandcooperationofmanyinstitutionsinmitigationeffortsisdesirableandevenessential,giventhatpollutionproblemsgenerallyhavecross-sectoralcausesandimplications.Buteffectivemanagementwilllikelyrequirethatanoverarchingresponsibilityisfirmlyplacedwithanagencygivenspecificauthorityfordeveloping,coordinating,andmonitoringenvironmentalprograms.Anagencyoragenciesshouldalsobeidentifiedasresponsibleforensuringcomplianceandenforcement.

Ongoingmanagementofairandenvironmentalqualityarenecessarilynationalresponsibilities.RatherthansimplyadoptamodeldevelopedforacityintheUnitedStates,forexample,eachdevelopingcountryultimatelywillhavetoevolveitsownpollutionmanagementmodel,basedonitsdistinctivepatternsofeconomicgrowth,demography,geography,andpublicpriorities.This,inturn,willrequiretheresponsibleagenciestohavecompetenceinthetechnicalandpolicyaspectsofenvironmentalmanagement.Theywillneedtodevelopdispersionmodels,correlateepidemiologicaldatawithambientpollutionconcentrations,andusethisdatatodevelopcost-effectiveintegratedairpollutionprograms.

Theywillalsoneedtoquantifyandevaluatethebenefitsofincreasedproductivity,reductionsinmortality,andimprovementsinthequalityofliferesultingfromairqualityimprovementsothatthemodelcandevelopandadapttochangingprioritiesandpatternsofgrowth.Stafftrainingthusmustbeatthecoreofanyprogramtomitigateairpollution.Similarly,environmentalagenciesmustdevelopthecompetenceandinstitutionalclouttomobilizetheneededresources.

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DevelopinganIntegratedProgramtoManageAirPollution

Puttinginplaceanintegratedairpollutionmanagementprogramandmeetingallinstitutional,staffing,training,andequipmentrequirementscouldtakeadecadeormoreinmanydevelopingcountries.YetmanyareasinSouthAsia,EastandWestAfrica,andLatinAmericahavealreadyreachedcrisisornear-crisislevelsofdegradationinairquality.TheycannotaffordtowaitforadecadetocountertheilleffectsofleadandSPM.Therecommendationssketchedbelowthusareintendedtoassistcountriesinaddressingairpollutionconcernsanddevelopingstrategiesimmediately.

IdentificationoftheAirPollutionProblem

Assessment.Thestartingpointforanyabatementprogramisanaccurateassessmentofcurrentambientairquality.Ifreliabledatadonotexist,andiflocalcollectionandadequateanalyticalskillsarenotathand,specializedfirmswiththenecessaryequipmentandstaffareavailable.Ideally,airqualityatcriticalpointsshouldbemonitoredoverayeartoaccountforseasonalvariationsinwinddirection,precipitation,andtemperature.Alternatively,monitoringcanbedoneoverthreetosixmonthsifitcaneffectivelyprovidedatarepresentativeofambientairpollutionconcentrationsthroughouttheyear.Asthestudyhassuggested,themostlikelypollutantsforstudywillbeCO,CO2,NOx,SOx,SPM,HC,andlead.Analysisofthecollecteddatashouldhelpidentifyspecificpollutantsthatareabovepermissiblelevels.

ProjectionofEmissionsGrowthandDevelopmentofaModel.Theassessmentexercisemustbefollowedbyaprojectionofthelikelyfuturedimensionsoftheproblem.Thisworkshouldbeginwithassessmentsofcurrentemissionsandintegrateexpectedchangesinthelevelsofthesepollutantsoveratleasta10-yearperiod.Estimating

thechangesinemissionswillrequireprojectionsofchangesinpassengertransportmiles,shiftsfromautomobilestomasstransportsystems,andalterationsinlikelyvehiclespeedsstemmingfromchangesinvehiclepopulationsmeasuredagainstimprovementordegradationofthetransportinfrastructure.

Emissionmodelsthatcanpredictlikelyambientconcentrationsofpollutants,basedonprojectedemissions,shouldthenbedeveloped.Thisdatacouldthenbeusedtoidentifypollutantspeciesatriskofexceedingstandards.

CorrelationwithEpidemiologicalData.Epidemiologicaldatafromhospitalsandotheragenciesshouldbethestartingpointforidentifyinglinkagesbetweenambientpollutionlevelsandchronicoracutehealthproblems.Wheredocumenteddataarenotavailable,healthrecordsofpatientsfrommetropolitanareascanbeexamined.Formonitoringpurposes,establishmentofalaboratorycapableofgauginghumanexposuresandtoxicitylevelswillberequired.Thisphaseofdatagatheringwillconstituteacriticalphaseindevelopingameaningfulairqualitymanagementprogram,innosmallmeasurebecauseitbeginstheworkofputtingahumanfaceonthedata.

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ValuationofPollutionImpactsandBenefitsofReduction.Thebenefitsofreducingpollutioncanbeprojectedclearlyonlyafteractivitiesdescribedintheprecedingparagraphshavebeencarriedout.InThailand,forexample(seechapter5),theprojectedhealthbenefitsofa20percentreductionofpollutionwerethebasisforillustratingthedimensionsoftheproblemandwinningsupportformitigationefforts.Airqualitymanagementprogramswilllikelybemostsuccessfuliftheyincludesimilarassessmentstojustifythenecessaryexpenditures.

MitigationOptionsandStrategies

Asdiscussedinthereport,airpollutionistheresultofmanyfactors.Eliminatingthesefactorsorreducingtheireffectsrequiresapplyingadvancedtechnicalskillsandsubstantialcapital.

LeadasaCaseExample.Thesophisticationrequiredforasuccessfulmitigationstrategycanbeillustratedbyadiscussionoftheproblemsinremovingleadfromgasoline(theprimarysourceofleademissionsinmetropolitanareas).Ofcourse,theleadcouldsimplyberemovedornotaddedtobeginwith,butthiswouldreducetheoctanevalueofgasoline,causingmechanicalandemissionsproblems.However,themostcommonoptionsforcompensatingforthelostoctanehavetheirowndrawbacks.Moreseverereformingofgasolineincreasesoctanebutalsoincreasesemissionsofcarcinogenicaromaticsandbenzene.Addinghigh-octane-valuelightendsalsoincreasesoctanebutatthecostofincreasingvaporpressureandhydrocarbonemissions.Evenaddingoxygenatesmaybeproblematic,assomearehighlyvolatileandtoxic.

Otheroptionsforreducingleademissionsmayrequirecomplextechnicalandsocioeconomicstrategies.Forexample,moreefficientvehicledesignswillresultinlowerconsumptionofgasoline,andamoreefficientin-cityroadandtrafficsystemwillincreasevehicle

speed,reducegasolineconsumption,andtherebylowerleademissions.Amasstransitsystemwouldshiftautomobilepassengerstoamoreefficienttrainsystem,thusreducingtrafficcongestionandpollution.Similarly,trafficmanagementorenergydemandmanagementstrategiescanbeeffectiveinreducinggasolineconsumptionandtherebyreducingtheemissionoflead.Alloftheseoptionscutacrosssectorsandoftenrequirelarge-scaleplanningandinvestment.Inshort,manyoptionsareavailableforreducingemissionsofleadandmostotherpollutantsandeachoptionhascriticaltimeandcostfactors.

ShapeofaStrategy.Clearly,awell-designedairqualitymanagementprogrammusteffectivelyweighthemanyfactorsinvolvedinthechoiceofmitigationoptions.Themostimportantofthesefactorsarecosts,implementationtime,theepidemiologicalimpactofthedifferentpollutants,andtheexpectedbenefits.Onthebrighterside,actionstoreduceonepollutantareoftenlikelytohavethebeneficialeffectofreducingotherpollutantsaswell.Forexample,reductionoftrafficcongestion,mayreducenotonlyleadbutallotheremissionslinkedtocombustionoftransportfuels.Addressingonepollutant

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atatime,ontheotherhand,maybecounterproductiveandultimatelytooexpensive.Anintegratedandcomprehensiveapproachisneeded.

Thekeytothedevelopmentofasuccessfulprogramisitstechnicalandeconomicfeasibility.Establishingrealisticgoalsbasedondemonstrableurgencyisessentialtoobtainthefundsrequiredfromwithinacountry'sownresourcesandfrominternationalagencies.Anewmasstransitsystem,forexample,mayreducetrafficcongestion,buttheinitialcostsofsuchsystemsaregenerallyhigh,andimplementationmaytakealongtime.Moreover,aspointedoutinchapter6,areviewof20masstransitsystemsshowedthatnonewasprofitableunlessthehealthandenvironmentalbenefitswerecarefullyfactoredinastheywouldhavetobetohaveanyhopeofjustifyingthenecessarystatesubsidies.

Acomprehensiveanalysisandapproachdoesnotmeananattempttosolveallproblemssimultaneously.Suchanapproachislikelytobesocomplexandexpensivethatitstopstheprogramaltogether.Amorepracticalstrategyistosetcoreprioritiesbyrankingpollutantsinorderoftoxicity,adversehealtheffects,andresultingcoststotheeconomy.Thisallowsplannerstoidentifysecond-orthird-stageactivitiesforimplementationaseconomicconditionsimproveorastheadverseimpactsofotherpollutantsbegintoincrease.

RoleofInternationalAssistance

Establishingrigidnationalorinternationaltargetsorstandardswithoutappropriateprogramstoachieveobjectiveswouldbeasfruitlessasdictating,say,thatacountryshouldsimplydoubleitsGDPinayear.Internationalagenciescanplayafruitfulrolebyprovidingtechnicalassistancetohelpcountriesdevelopenvironmentalmanagementprograms.Sustainedmitigationeffortsmustremainanationalresponsibility,butinternationalagenciescanhelpcountriesidentifyandfulfilltheirinstitutional,staffing,training,equipment,and

laboratoryrequirements.

Intheinitialstageofinternationalassistance,priorityobjectivesmayincludeestablishingprogramstomeasureambientairquality,developingepidemiologicaldata-gatheringsystems,establishingstandardsforambientairquality,identifyingcurrentandlikelyfutureairpollutionproblems,developingmodelstomeasuretheimpactofemissions,establishingtargetsforpollutionreduction/containment,andvaluingthepotentialbenefitsofreducingpollutionandthecostsofinaction.

AnencouragingprecedentforsucheffortsistheMexicoCityairpollutionprogram.Inthiscase,WorldBankstafftooktheleadroleandcalledonassistancefromothertechnicalspecialistsandeconomistsasrequired.Amonitoringpanelwasalsoformedtoreviewtheworkofthespecialists.Theresultingprogramhasbecomeabasisforseveralsimilarprogramsinothercountries.Mostdevelopingcountrieswillrequiresimilarteamefforts,evenifnotonthescaleoftheMexicoCityprogram.

Althoughdevelopingcountriesaccountformorethan60percentoftheworldpopulation,theycurrentlyaccountforlessthan30percentoftheworld'semissionsof

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greenhousegases.Butifmitigationmeasuresarenotestablished,theirsharewillsoonexceedthatofthedevelopedcountries.Greenhousegasesfromdevelopingcountrieswillalmostdoublewithin10years.Itisthusclearlyintheinterestofbothdevelopedanddevelopingcountriestocontainorreversethegrowthofgreenhousegasemissions.

Internationalfinancialassistancemayberequiredtobuildairpollutionmitigationmeasuresintoexistingprojectsortoincorporatethemintonewprojects.Generally,projectswillnotbeabletoabsorbthesignificantadditionalcosts,andtheeffectofpassingtheincreasesontoconsumers(particularlyforfuelssuchasdiesel,whosepriceaffectsprimarilylow-incomeconsumers)couldbesociallyandpoliticallydisastrous.Confrontedbydomesticunrest,governmentsinseveraldevelopingcountrieshavealreadyhadtoretreatfromplanstoeliminateconsumerenergysubsidiesortoimplementfullycost-reflectiveenergytariffs.

Concessionaryfundingarrangementsmaybeanessentialtoolinanefforttopromoteabatementandminimizecosts.Sucharrangementswouldlikelyrequirecountriestohaveintegratedairqualitymanagementprogramsthatcaptureallfactorscontributingtoairpollutionandrankoptionsformitigation.Fromtherankingwouldflowmutualdecisionsregardingfundingofmitigationactivitiessuchashighwayimprovement,fuelsreformulation,trafficmanagement,andsoon.Ofcourse,systematicmitigationeffortsareamajorundertaking,evenifsubsidized,andthedetailsoffinancing,management,andimplementationinvitesubstantialfurtherdiscussion.

Itremainsclearthatacloserrelationshipbetweencountriesandinternationalagenciesonhowtocombatairpollutionisneeded,andthatresults-oriented,integrated,airqualitymanagementshouldreceivehighpriorityintheplansofalldevelopingcountries.

Ultimately,integrationofalllocalairqualitymanagementeffortswillbeessentialifglobalproblemssuchasgreenhousewarming,acidrain,andozonedepletionaretobebroughteffectivelyundercontrol.

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GlossaryAcidrain:RainfallthathasapHlessthanabout5.6,thevalueobservedwhenpurewaterissaturatedwithatmosphericcarbondioxide.Acidraintypicallycontainssulfuricacid,nitricacid,orboth.

Aerosol:Asuspensionoffinesolidorliquidparticlesingasorair,suchassmoke,fog,andmist;also,theparticlesthatmakeupthissuspension.

Airquality:Ambientpollutantconcentrationsandtheirtemporalandspatialdispersions.

Aldehydes:AnorganiccompoundcontainingtheC=Ogroup,generallyrepresentedas&obc:,whereRmaybeanaliphatic(q.v.)oraromatic(q.v.)compound.

Aliphatics:Agroupofstraightchainedhydrocarbons.Typicalaliphaticsareethanol,methanol,propane,andformaldehyde.

Ambientairquality:Theexistingstateoftheatmosphericpollutioninanoutdoorarea.

Ambientstandards:Thosestandardsconcernedwiththeoverallairqualitysurroundingacommunityoranindustrialarea;theseareusuallysetataleveldeemedsufficienttoprotectpublichealth.

Aromatics:Agroupofcyclicallystructuredhydrocarbonsofwhichbenzeneistheparent.Theyarecalledaromaticsbecausemanyoftheirderivativeshavesweetaromas.Thesehydrocarbonsareofrelativelyhighspecificgravityandpossessgoodsolventproperties.Certainaromaticshavevaluableanti-knock(octane)characteristics.Typicalaromaticsarebenzene,toluene,andxylene.

Benzene:Apurearomatichydrocarbon(q.v.)ofcharacteristicodor

occurringinsignificantproportionsincertainFarEasterncrudeoils.

Catalyst:Asubstancethataffectstherateofareactionwithoutbeingusedupitself.

Catalyticconverter:Adevicebuiltintotheexhaustsystemofanautomobilecontainingacatalystgenerallymadeupoffinelydividedplatinum(Pt),rhodium(Rh),andpalladium(Pd),whichconvertscarbonmonoxide(CO)tocarbondioxide(CO2);unburnedhydrocarbonstoCO2andwater(H2O);andnitrogenoxide(NO)tonitrogendioxide(NO2),nitrogen(N2),andoxygen(O2).

Chlorofluorocarbons:ThesecompoundsarealsoknownasfreonsandconsistofCFCl3andCF2Cl2.Mainlyusedasrefrigerants,theyareasourceofchlorineatomsintheupperatmosphere.

CleanAirAct:U.S.Congressionalactsandamendmentstopromoteimprovementsinairquality.

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Conformityofproduction:Thisreferstothetestingofsamplevehiclesfromaproductionruntodeterminewhetherthevehiclesmeetestablishedemissionsstandards.

Dispersion:Themannerinwhichatmosphericpollutantsareconveyedanddilutedbywindandturbulentmixing.

Dollars:AllpricesandcostsinthisreportareexpressedinU.S.dollars.

Effluent:Pollutantmaterialsdischargedintotheenvironment.

Emissionrate:Therateatwhichpollutantsarereleasedfromanexhaustsystem.

Emissionstandards:Standardsforpollutantsfromspecificsources,suchassmokestacks,ventilationsystems,andautomotiveexhaustsystems.Itisalegallimitontherateofsuchemissions.

Globalpollutants:Damagecausedbyglobalpollutantsisevidencedworldwide(e.g.,throughglobalwarming).Thegreenhousegases,whichincludecarbondioxide,nitrousoxide,methane,ground-levelozone,andchlorofluorocarbons,areoneclassofglobalpollutants.

Greenhouseeffect:Theabsorptionofoutgoinginfrared(IR)radiationbywatervaporandcarbondioxide,whichtherebyraisestheearth'stemperature.

Hydrocarbons:Materialscomposedentirelyofcarbonandhydrogen.Thecarbonatomsmaybeinlinear(aliphatic)orring(aromatic)formations.

Inspectionandmaintenance(I/M):AU.S.emissionstestingandinspectionprogramimplementedinnonattainmentareas(q.v.)toensurethatvehiclesmeetemissionsstandards.

Inversion(thermalinversion):Areversalofthenormalatmospheric

temperaturegradientwherethetemperatureincreaseswithaltitude.

Localpollutants:Theseincludelead,sulfuroxides,particulatematter,carbonmonoxide,ground-levelozone,andnitrogendioxide.Damagecausedbythemisevidencedinthevicinityofemissions.Alocalpollutantmayalsobearegionalpollutant(q.v.).

Naphtha:A"cut"coveringtheendofthegasolinerangeandbeginningofthekerosenerange.Itisfrequentlyusedasafeedstockforreformingprocessesandisalsoknownas"heavybenzene"or"heavygasoline.''

NationalAmbientAirQualityStandards(NAAQS):PollutantstandardsdevelopedbyU.S.EnvironmentalProtectionAgency.

Nonattainmentarea:Anareathathasnotmetorisunlikelytomeetnationalambientairqualitystandards.

Octanenumber:Thisisameasureofgasoline'santi-knockvalue.Thehighertheoctanenumber,thehighertheanti-knockqualityofgasoline.

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Ozone:Abluishirritatinggasofpungentodor.ItisanallotropicformofoxygeninwhichthemoleculeisO3.

Photochemicaloxidants:Toxicgases,mainlycolorless,thatareproducedinthepresenceofsunlightfrominteractionofhydrocarbonsandnitrogenoxides.Ozone,formaldehyde,peroxylnitrate,acrolein,andperoxybenzoicnitrateareexamples.

Photodissociation:Dissociation(asofNOx)undertheinfluenceofradiantenergy.

Pointsource:Asingleoriginofemissionsstationedatafixedpoint.

Pollutant:Acontaminant,orforeignspecies,presentinasample;usuallyhasadeleteriouseffectonqualityofsampleasfaraslivingthingsareconcerned.

Primarypollutant:Achemicalcontaminantemitteddirectlytotheatmospherebyasource.

Primarystandard:ThisisaspecificationsetbytheNationalAmbientAirQualityStandards(q.v.)toprotecthumanwelfareandhealth.

Reforming:Aprocessinwhichstraight-runfeedstocks(e.g.,naphtha)aresubjectedtohightemperaturesandpressureswiththeobjectofchangingtheirchemicalstructureinsuchawayastoincreasetheiroctanenumber(q.v.).

Regionalpollutants:Regionalpollutantsaresulfuroxides,nitrogenoxides,andozone.Aregionalpollutantmayalsobealocalpollutant(q.v.).Damagecausedbyregionalpollutantsoccursatsignificantdistancesfromtheemissionpoint.

Secondarypollutant:Atmosphericcontaminantsformedbychemicalprocesses,suchashydrolysis,oxidation,andphotochemicalreactions.

Smog:Smokyfogcontainingharmfulspecies,suchassulfurdioxide

(SO2),sulfurtrioxide(SO3),nitrogendioxide(NO2),andozone(O3).

Stratosphere:Theupperportionoftheatmosphere,from10to50kmabovetheearth'ssurface.

Troposphere:Theportionoftheatmospherebetweentheearth'ssurfaceandthestratosphere.

Ultravioletradiation:Lighthavingawavelengthgreaterthanabout10nmbutlessthan400nm.

Volatileorganiccompounds:Reactivehydrocarbonsemittedbyfossil-fueledmotorvehicles,evaporationofsolventsandgasoline,chemicalmanufacturing,petroleumrefining,andtoalesserdegreefromwastedisposalsitesandwastewatertreatmentplants.

Wavelength:Acharacteristicpropertyoflight,similartoitscolor,andequaltothelengthofafullwave;oftenexpressedinnanometers(nm).

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