Unit 7: Chapter 18

Chapter 12 Reading QuizWhich layer of the atmosphere is closest to earth? ThermosphereMesosphereTroposphereStratosphereHow are primary pollutants and secondary pollutants related?Which of the following is/are NOT common air pollutant(s)?CO2, SO2, O2, NO2, O3, H2OA photochemical reaction is a chemical reaction activated by _____________.What is the gas that constitutes the majority of photochemical smog?Air & Air PollutionChapter 12The AtmosphereLayers:TroposphereStratosphereMesosphereThermosphere

Temperature & Pressure relationships

This course will focus mostly on the 2 closest to earth (Trop & Strat)p. 2783Troposphere1st layer of atmosphereHas 75% mass of earths airConsists of 99% dry air (mostly N & O) Varying amounts water vaporPressure decreases with altitudeExtends 11 miles above sea level (as thick as an apples skin if the earth were an apple)Thinner at the poles (~5 miles)

78% N, 21% OVapor varies (.01% at poles, 4% in tropics)Argon 1%CO2 .037%Trace amounts of others4Stratosphere2nd layer of atmosphereContains much less matter than troposphere, but composition is similarVolume of water vapor is less Volume of ozone is much greaterOur health depends on having enough ozone in stratosphere and little introposphere.

Extends 11-30 miles above sea level (~twice as thick as troposphere)

1/1000 water vapor

Ozone = O3, produced when O2 reacts with UV sunlightglobal sunscreen keeps out 95% of harmful radiation

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Are we (humans) decreasing good ozone and increasing bad ozone?

Bad nearby, good up highGRAPH P. 279 (top)6Air PollutionPresence of one or more chemicals in the atmosphere in quantities and duration that cause harm to humans, other forms of life, and materials. Primary PollutantsEmitted directly into troposphereNatural and anthropogenic sourcesnatural events: dust storms, volcanic eruptions, firesanthropogenic: emissions from cars, smokestacks in power plants & factoriesstationary vs. mobileCan combine (with each other or other components of air) to form secondary pollutantsNatural sources are usually spread out and rarely reach harmful levels (except some major volcanoes)Most ambient air pollution in urban areas is from the burning of fossil fuels8Air Pollutants Commonly Found in Ambient AirCarbon oxidesSulfur oxidesNitrogen oxidesVOCsSPMPhotochemical oxidantsRadioactive substancesHAPs

p. 280Ambient = outdoor

CO, CO2SO2, SO3NO, NO2, N2O (NOX needed to form ozone limit NOX = limit ozone)Volatile Organic Compounds = CH4, CFCs (precursor to ozone limit VOCs = limit ozone)Suspended Particulate Matter = dust, soot, lead, etc. (clog alveoli in lungs)O3Radon, plutoniumHazardous Air Pollutants = carbon tetrachloride, etc.

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Primary PollutantsStationaryMobileNaturalMost hydrocarbonsMost suspendedparticlesSO2NONO2COCO2Secondary PollutantsSO3HNO3H2SO4H2O2O3PANsMostNO3andSO42saltsSecondary pollutants: ex- acid rain SO2/NOX combine with water vapor. Ex- ozone P. 27910NAAQSGovernment mandated maximum allowable atmospheric concentrations6 Criteria Air PollutantsCONO2SO2Particulate matterO3LeadCongress directed the EPA to establish National Ambient Air Quality Standards in most developed countries there are standards like theseBUT in ING they do not exist or are not enforcedThen, the mobile pollutant can blow into an area with strict emissions laws

p. 281 (list of 6 criteria pollutants, sources, & health/enviro effects)11Urban AreasCities normally have higher levels of air pollution (compared with rural areas).Air pollution is highly mobileCan spread via winds very easilyIndoor and outdoor air pollution high-risk human health problems1.1 billion people live in areas where air is unhealthy to breatheMostly cities & developing countries

Indoor air pollution will go with risk/toxicology unit (next unit)12Photochemical SmogMixture of primary and secondary pollutants formed under the influence of sunlight. Dominated by photochemical ozone. (O3)Highly reactiveHarms most living organismsHuman sources: chemical rxn with VOCs & NOxemitted mostly by cars/industryHealth effects: breathing problems, coughing, ENT irritation, aggravates asthma/bronchitis/etc.More than 100 chemicalsDiesel engines emit NOx14Photochemical SmogFactors influencing ozone levels/PC smog:HeatHotter = Higher levels of O3TrafficMore traffic (esp. stand still) = Higher levels of O3SunlightClear days (few clouds) = Higher levels of O3Cities with sunny, warm, dry climates and lots of motor vehiclesLA, U.S.; Sydney, Asutralia; Mexico City, MexicoStand still traffic is the worst because when a car emits the most/worst pollution when idling. 15Industrial SmogConsists mostly of sulfur dioxide, suspended droplets of sulfuric acid, and a variety of suspended solid particles and droplets. Source: power plants/factories burning large amounts of coal/heavy oil (high sulfur content) Examples: London, England; Pittsburgh, U.S.Where is industrial smog an issue?Industrialized urban areas of China, India, Ukraine (anywhere large amount of coal are burned without sufficient pollution control)Rarely a in developed countries (today)

More severe during the winter months 50+ yrs ago?

NOW, most coal/heavy oil is burned in factories/plants with large boilers & reasonably good pollution control or tall smokestacks-smokestacks: transfer pollutants to downwind areas not the best solution-Boilers: scrubbers to reduce SO2 emissions; catalysts to reduce NOx emissions

16Factors Influencing SmogLocal climate and topographyRain & snowWindsHigh temperaturesHills & mountainsPopulation densityUrban buildingsAmount of industryFuels used in industry, heating, transportationRain and snow help cleanse air of pollutantsWinds sweep pollutants away, dilute pollutants by mixing, bring in fresh airHigh temps promote chemical reactions that lead to PC smogHills and mountains reduce flow or air (esp in valleys) = pollutants build up a ground level (REMOVES BENEFITS OF WINDS)Urban buildings reduce flow or air/slow wind speed = reduce dilution and removal of pollutants (REMOVES BENEFITS OF WINDS)

17Temperature Inversion/ Thermal InversionWhen a layer of dense, cool air beneath can be trapped beneath a layer of less dense warm air in an urban basin or valley. Prevents mixing/dispersion of pollutantsSubsidence temperature inversionRadiation temperature inversionAreas especially susceptible to prolonged temperature inversions:Cities located in a valley OR with mountains on three sides and an ocean on the fourthSubsidence = caving in or sinking of an area of landSubsidence inversion = large mass of warm air moves into a region at a high altitude/floats over mass of cold air near ground

Radiation inversion = nighttime air near ground cools faster than the air above it usually disappears as sun rises

Cities in valley: mountains block out sunlight needed to reverse nightly radiation temperature inversionCities in valley: also hold in pollutants as warm air sits on top, no where for cool air to go

Ocean air/winds cool air near surface18Pollutantswarmaircool air surface heated by sun warm air rises (incl. pollutants) cools off, mixes with air of equal density & dispersescool airwarm air (inversion layer) surface cools rapidly (night) a layer of warm air overlays surface polluted surface air rises but cannot disperse remains trapped19Acid Deposition: What is it?Acid Deposition is the falling of acids and acid forming compounds from the atmosphere to the earths surface. a.k.a. acid rain.Sources: SO2, NOx (in emissions from coal-burning plants, mostly)Combine with water vapor to produce acid rainnitric acid, sulfuric acid, sulfate/nitrate saltsCan be wet, dry, or a mix

SO2/NOx are primary pollutants, acid deposition is secondary

Vapor or droplets formed, sulfate/nitrate salts are acid-forming particles

Wet = rain, snow, fog Dry = acidic particles Mix = acid depositionWer = takes about 4-14 days to fall (farther from source, downwind) Dry = 2-3 days to fall (close to source)21Acid Deposition: pHpH: measure of the concentration of hydrogen ions in a solutionpH < 7 acidicpH = 7 neutralpH > 7 alkaline or basicLower than 5.6 considered acid rain

Natural precipitation is slightly acidic: 5.0-5.6Typical rain in the US is now about 10X more acidic: 4.3Can be as acidic as 2.3 (1000X more acidic than natural rainwater)22Acid Deposition: Where?What areas are affected?Regional (as opposed to global)Downwind coal burning power plants, factories, larger urban areas with many motor vehicles.Plants/factories will use smokestacks that reach above the inversion layer to release emissionsReduces local air pollutionIncreases regional air pollution23

Acid Deposition: Where?Many coal burning industries/factories in Ohio Valley

p. 286 for world mapEastern US, Europe, S.E. China

MOBILE so can be transported to location where there is not actually activity leading to acid rainEx: Southeastern Canada acid deposition can be traced to emissions from Ohio Valley and vice versaLICHEN ARTICLE at beginning of Ch. 12 (coal-burning facilities in Thunder Bay, Canada harmed lichen on Isle Royale)24Acid Deposition: EffectsEcological problems = medium risk Human problems = high risk

Can cause serious and costly ecological and economic effects25Acid Deposition: Ecological EffectsHow seriously vegetation and aquatic life in lakes are affected depends mostly on whether its soils are acidic or basicSome soils contain natural buffers:Soils eroded from parent material with alkaline properties (i.e. marble, limestone):Slightly basic and can (at least partially) neutralize acid rain as it percolates through the soil horizonsCan lose buffering capacity through prolonged acid rainIf only thin, acidic soil:No buffering capacityBuffer or neutralizer26Acid Deposition: Ecological EffectsTerrestrial:Hardest hit areas - mountaintop forestsTend to have thin soils w/out much buffering capacityExposed to acidic fog (high altitudes)Leach soil of nutrients = difficult for plants to growTrees directly affected damaged foliageInterferes with photosynthesisWater lossMakes trees more susceptible to other stressesAnimal life affected cant get food, lost habitat

Mountain top forests usually have lots of conifers, which have acidic needles anyway

Other stresses: cold temperatures, diseases, insect attack, drought, fungi, etc.

Promote growth of acid-loving mosses, which can kill trees and outcompete endemic/healthy mosses

SEE FIGURE 12-11, P. 288

ALL OF THIS IN ADDITION TO HARMFUL EFFETS OF OZONE = bad news bears27Acid Deposition: Ecological EffectsAquatic:Acidic runoff lowers pH of lake/pondMost cannot tolerate lower than 5Acid shock kills fishLoss of fish and other populationsEcosystem collapseContaminate fish in some lakes with highly toxic methyl mercury (emitted by coal burning plants)Organisms (including humans) that eat the contaminated fish may experience negative health effects.Neg. health effects: kidney failure, brain damage, death

Some aquatic organisms more tolerant than others see p. 287 figure 12-10

Can add lime to neutralize acidic lakes, but not permanent (must be done each year if the source of the problem is not addressed) AND it can kill some species and is difficult to determine how much/where to use

Add phosphate fertilizer to neutralize? Then what? Eutrophication?

28Acid Deposition: Human EffectsHuman healthContributes to human respiratory diseases (bronchitis/asthma)Can leach toxic chemicals into drinking waterCan damage statues, buildings, metals, car finishesDecreases visibilityLowers productivity in fisheries, farms (due to weak soils and direct harm of foliage)Many of the same effects as ozone29Acid Deposition: Reduction/PreventionPrevention Solutions:Reducing energy useImproving energy efficiencyCoal:Removing sulfur from coal before it is burned ORBurning low sulfur coalInstalling scrubbers and catalysts in boilers to reduce SO2 and NOxEven BETTER: Switching from coal to Cleaner burning natural gas ORRenewable energy Tax emissionsONCE AGAIN, the best solution is prevention as opposed to clean up (least harmful to environment, and least costly $$)

Hard to motivate because often the effects are far from the cause (air emissions extremely mobile via winds)Coal is a major energy resource, especially for countries that have a lot on hand (China, Russia, US)Expensive- especially on large scale for industry/factories (removing sulfur, low-sulfur coal, scrubbers/catalysts)30Preventing & ReducingAir Pollution32LawClean Air Acts of 1970, 1977, & 1990Pollution regulationsEPA established:National Ambient Air Quality Standards- NAAQSCO, NO2, SO2, particulate matter, O3, leadnational maximum emission standards for toxic air pollutants (known/suspected to cause cancer and other adverse health effects)

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34Law: Is it working?1970-1998: Criteria pollutant total emissions declined even when population was increasingIncreasing production & vehicular travel1978-1998: Lead down by 97%Get the lead out lead banned in gasolineCO down 60%SO2 down 58%O3, SPM down35Law: Is it working?1970-1998: NOx emissions increased by11%World: 62 million people still live in areas where the air still does not meet the primary standardsU.S.: about half our population lives in an area with dangerously high smog levels

36Law: Improvements?Focus on pollution prevention (rather than cleanup)Increase fuel efficiency standards- carsRegulate emissions from 2-cycle enginesRequire stricter emission standards for fine particulates

2-cycle = lawnmowers, leaf blowers, chain saws, marine engines (boat, jet ski, etc.)1 hr. ride on jet ski air pollution > avg. car in 1 yr. WHAT?! . And.. Oil spilled from marine engines = 15X more/yr. Exxon Valdez37SO2 CreditsEmissions trading policy Allowable under CAA 1990Buy & sell SO2 pollution rightsPlant uses less than their allotted pollution rights allow?More emissions in another facility, bank for future, or sell to another plant/citizen/enviro. gp.Goal?Net reduction in SO2 pollution Environmentalists want to gradually reduce the number of credits allotted annuallyBad? Allows utilities to keep on emitting unacceptable levels, buy their way outCHEATING- relies on self-reporting. Need an auditing system

These types of programs suggested for NOx, particulates, and VOCs38Reducing Outdoor Air PollutionPreventionSO2, NOx, particulates:Burn low-sulfur coalRemove sulfur from coalConvert coal to a liquid or gaseous fuelShift to less polluting fuelsCleanup:Disperse emissions above thermal layer (tall smokestacks)Remove pollutants after combustionSee p. 296 Figure 12-18Tax units of pollutionSAME as reducing acid deposition because (some of) these primary pollutants lead to acid rain

Doing these things will also limit O3 since NOx O3

THIS IS FOR STATIONARY SOURCES

39Reducing Outdoor Air PollutionPreventionmobile emissions:Increase use of mass transit, bicycles, walkingLess polluting & more effifient fuels/enginesGet old cars off the roadRestrict driving or tax emissionsCleanupEmission control devicesEx: NOx from diesel engines

Some prevention methods are expensive = hard to motivate individuals/industry to participate

THIS IS FOR MOBILE SOURCES

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SCR technology is one of the most cost-effective and fuel-efficient technologies available to help reduce diesel engine emissions. All heavy-duty diesel truck engines produced after January 1, 2010 must meet the new EPA standards, among the most stringent in the world, reducing particulate matter (PM) and nitrogen oxides (NOx) to near zero levels. SCR can reduce NOx emissions up to 90 percent while simultaneously reducing HC and CO emissions by 50-90 percent, and PM emissions by 30-50 percent. SCR systems can also be combined with a diesel particulate filter to achieve even greater emission reductions for PM. In the commercial trucking industry, some SCR-equipped truck operators are reporting fuel economy gains of 3-5 percent. Additionally, off-road equipment, including construction and agricultural equipment, must meet EPA's Tier 4 emissions standards requiring similar reductions in NOx, PM and other pollutants. 41Protecting the AtmosphereFocus more on pollution preventionIntegrate air-pollution, water-pollution, energy, and land-use policiesRegulating air quality for larger regionsImprove energy efficiencyLess FF, more renewable energySlowing population growthDistribute cheap and efficient or solar cookstoves in developing countriesSome places have seen great improvements: Toyko, W EuropeOther are just as bad/worse: urbanized areas of developing countries

air shed- so its harder to just pump your pollution somewhere else

42Indoor Air PollutionChapter 12, Sections 5 & 6Types and Sources of Indoor Air PollutionHigher in homes and commercial building than outdoors, as much as 70 times.Pollution levels inside cars in traffic clogged urban areas can be up to 18 times higher.At greater risks are smokers, infants, children under age 5, the old, the sick, pregnant people, people with heart problem.

ContinuedPollutants found in building to be: dizziness, headaches, coughing, sneezing, nausea, burning eyes, chronic fatigue, and flu like symptoms, known as sick building syndrome.New ones are more commonly sick than old ones because of reduced air exchange.ContinuedCan be mineral fibers falling from ceiling tiles and blowing in from the lining of the air conditioning ducts.Cigarette smoke, formaldehyde, asbestos, and radioactive radon are the most dangerous.

How human health is harmed?Lung cancerAsthmaChronic bronchitis Emphysema

What pollutants cause these problems?Suspended particulate matter: asthma Fine particlesUltrafine particlesSulfur dioxide: asthma/ bronchitisNitrogen oxides: asthma/ bronchitisVolatile organic compounds: cancer

Humans Die from PollutionAnnually, U.S. estimates 65,000-200,000 premature deaths from outdoor pollutionIndoor pollution included: 150,000-350,000 premature deathsWorldwide: 2.7 million premature deathsMillions more face illness

Reducing Indoor Air PollutantsUsing simple stoves that burn more efficiently (reduces deforestation)Using simple solar cookersBreathing wallAbsorbs indoor dirty airExhales clean air