Annual air pollution caused by the Hungry GhostFestivalB. Khezri,abY. Y. Chan,acL. Y. D. Tiongaand R. D. Webster*abcBurningofjosspaperandincenseisstill averycommontraditionalcustomincountrieswithamajorityChinesepopulation. TheHungry Ghost Festival whichis celebratedinthe7 monthof theChinesecalendar is one of the events where joss paper and incense are burned as oerings. This studyinvestigates the impact of the Ghost Month Festival (open burning event) on air quality by analysis of thechemical compositionof particulatematter (PM) andrainwater samples collectedduringthis event,comparedwithdatacollectedthroughout theyear, aswell asbottomashsamplesfromburningtheoriginal josspaper and incense. The results showed thatthechange inthechemicalcompositionoftherainwater andPM2.5(PM#2.5 mm) atmosphericsamples couldbecorrelateddirectly withburningevents duringthis festival, withmanyelements increasingbetween18%and60%duringAugust andSeptember compared to the yearly mean concentrations. The order of percentage increase in elementalcomposition (in rain water and PM2.5) during the Hungry Ghost Festival is as follows: Zn > Ca > K > Mg >Fe>Al >Na Mn Ti V>Cu>As>Ni >Co>Cd>Cr>Pb. Thechemical compositionof theoriginalsourcematerials(josspaperandincenseforcombustion)andtheirassociatedbottomashwereanalysed to explain the impact of burning on air quality.Environmental impactUncontrolled outdoor burning of paper objects and incense is commonly conducted in countries with Chinese populations as part of religious ceremonies. Inthis study, we have identied a signicant source of atmospheric pollution above normal background levels that occurs in August/September each year, due tothe Hungry Ghost Festival. The pollution takes the form of an increase in the metallic composition of particulate matter # 2.5mm (PM2.5) released into theatmosphere as well as a measurable contamination of rainwater. The compositions of the PM2.5 and rain water were compared with the chemical composition ofa range of common materials that are burnt as oerings (Joss paper, incense and papier-mache) for source apportionment.1 IntroductionKnowledge of the concentrations of trace elements in particu-late matter is an essential primary step in identifying the sourcecharacteristics of air pollution for the development of air qualitycontrol strategies and evaluating possible implications forpublic health. Several epidemiological studies have identied acorrelationbetweenthe exposure to airborne particles andincreasedhealthrisksuchasmortality,respiratoryorcardio-vascular diseases, and respiratory symptoms.1Rainplaysaroleintheremoval of gasesandparticulatematter from the atmosphere, therefore, the study of the chem-ical composition of rainwater can also aid in understanding thecontributionof thedierent sources of atmospheric pollut-ants.2The rainwater composition is oen inuenced byanthropogenic activities releasing acidic (such as SOx and NOx)or basic (such as NH3) gases into the atmosphere. Acidic rain-water aids the dissolution of many trace metals, whichenhances their bioavailability, thus, the study of trace metals inrainwater has increased because of their adverse environmentaland human health eects.Anongoingstudywasconductedcommencingin2009tomonitor rainwater and airborne particulate matter in asampling site inwesternSingapore. One of the interestingfeatures uncovered in this dataset is a local event (common inall countries witha Chinese population), calledthe GhostMonth, that surprisinglysubstantiallychangedthechemicalcomposition of rainwater and particulate matter by increasingtheconcentrations of alargenumber of theelements. TheHungry Ghost Month is a traditional festival celebrated by theChinese inthe seventhmonthof the lunar calendar. TheyaDivision of Chemistry and Biological Chemistry, School of Physical and MathematicalSciences, NanyangTechnological University, Singapore637371, Singapore. E-mail:webster@ntu.edu.sg; Fax: +65-6791-1961bCambridge Centre for Carbon Reduction in Chemical Technology,CARESCAM.CREATE, Nanyang Technological University, 62 Nanyang Drive,Singapore 637459, SingaporecNEWRI-ECMG, Nanyang Environment and Water Research Institute (NEWRI), 1Cleantech Loop, Clean Tech One, #06-08, Singapore 637141, Singapore Electronic supplementary information (ESI) available: Full tables of elementaldata, mapsof samplinglocations, instrumental parametersusedfor analysisand photographs of materials for burning. See DOI: 10.1039/c5em00312aCite this: DOI: 10.1039/c5em00312aReceived 5th July 2015Accepted 16th July 2015DOI: 10.1039/c5em00312arsc.li/process-impactsThisjournal isTheRoyal SocietyofChemistry2015 Environ. Sci.:ProcessesImpactsEnvironmentalScienceProcesses & ImpactsPAPERPublished on 16 July 2015. Downloaded on 14/08/2015 04:32:16. View Article OnlineView JournalbelievethatthegatesofHellareopenedtoallowghostsandspirits access to the world of the living on therst day of themonth. The spirits visit their families, feast and look for victimsduring this month. Theeenth day of the seventh month inthelunarcalendariscalled theHungryGhostFestival (GhostDay/Lu Yan). Ghosts are in a heightened state and it is impor-tant to hold a large feast to please them and bring luck to thefamily. In the last day of this month the ghosts and spirits leavethe earth and the gates of Hell nally close. These threeimportant days are celebrated and family members pray to Godand for their ancestors, make oerings of food and drink andburnasignicantamountofjosspaper,hellbanknotesandincense throughout Singapore (and other countries with aChinese population). Fig. 1 illustrates the large scale burning ofjoss paper in the aernoon of the 15th day of the Ghost Month.Fig. S1 (Groups A, Band C) and Video S1 in the ESI providemore details about Ghost Month celebrations. In recent years,new luxury goods made from joss paper, cardboard or papier-mache have been introduced into the market for burning, withthe items ranging from representations of clothing, computers,cars, houses, jewelry, watches, beercansandevenmodelsofservants.Despitethehighnumberofburningevents, relativelyfewstudies have beenperformedregarding pollutants releasedfrom joss paper and incense which are known to generate largequantities of particulates.3The burning process has also beenshown to release polychlorinated dibenzo-p-dioxin/dibenzo-furan(PCDD/F),polycyclicaromatichydrocarbons(PAH)4andmetals.5Large scale burning of joss paper and incense oen occursduringimportantoutsidefestivals, althoughpreviousstudieson joss paper and incense burning have concentrated mainly onassessing the air quality of the indoor/outdoor environments oftemples.4a,e,5c,d,6To the best of the author's knowledge, only onestudyhasbeenperformedoncharacterizingtheambientairPAH concentrations emitted during a massive joss paper open-burningeventheldatasuburbansite,4cwhiletheelementalcompositions emitted from open air burning of joss paper havenever been investigated. Consequently, this study was aimed atinvestigating the impact of outdoor burning of joss paper andincenseduringtheHungry Ghost Festival onair quality inurban areas. In order to dierentiate between the backgroundairpollutionof Singaporeandtheconcurrencyof theGhostmonthwithhazeeventsbroughtaboutbytransboundaryairpollution(duetobiomassburninginIndonesia), theGhostMonth data were compared with long-termenvironmentalsamplingcollectedovera5yearperiodatasiteatNanyangTechnological University (NTU). The average PM10value inSingapore is 40 mg m3. PM10 values above 60 mg m3are typi-cally associated withthe transboundary air pollutionfrombiomass burningevents (haze) fromnearby Indonesia. Inorderto removeuncertainty in the pollutionoriginating fromthe Ghost festival with coincident pollution fromtrans-boundarybiomassburning, datafromdayswithPM10>60values were excluded from the comparisons.The atmospheric PMdetecteddue tothe Ghost Monthburning events will naturally increase as the sampling deviceisplacedcloser tothepoint of burning. Inthisstudy, thesampling site was located away from residential areas so thatthere was no burning associated with the Hungry GhostFestival within a 2 km radius (the sampling site location andthe closest burning site locations are provided in Fig. S2(b) inthe ESI). We were interested in determining how the HungryGhost Festival aectedthe backgroundpollutionlevels inairborneparticulatematterandrainwater, whichrequiredacomparisonwithdatacollectedfromahighvolumePM2.5sampler and rain collection system over a long period. Sinceno long-term background data are available at the sites usedforburning,theNTUsiteprovidedthebestmeasureofhowbackgroundlevelsvariedduetotheHungryGhost Festival.The increase in elements in the PM2.5 and rainwater observedover the Hungry Ghost Month indicated that the burnt mate-rialwasdispersedreadilyintotheatmosphere.Theenviron-mental data were compared with data collected from unburntandburnt (ash) samplesof commercial josspaper, incenseand papier-mache oerings.2 Materials and methods2.1 SamplingRainwater (using anautosampler, NewStar EnvironmentalLCC, US) andparticulatematter (usingEcotechair samplerHiVol-3000, Australia) samples were collected within thecampus of NanyangTechnological University, inSingapore,from August 2009 onward. Airborne particulate matter sampleswerecollectedonEmfablters (Borosilicateglass microbersFig. 1 (Upper) Preparing, and(lower) burningof josspaper ontheGhost Day (15th day).Environ. Sci.:ProcessesImpacts Thisjournal isTheRoyal SocietyofChemistry2015Environmental Science: Processes & Impacts PaperPublished on 16 July 2015. Downloaded on 14/08/2015 04:32:16. View Article Onlinereinforced with woven glass cloth and bonded with PTFE, size:8 10inch, Pallex, EmfabTX40HI20-WW, Pal, USA). Thislocation encompasses dierent potential sources of anthropo-genic activities as it is located approximately 8 km north of theTuasand Jurong Islanddistricts which are the most industri-alized areas of the country, and also lies within 300 m of the PanIslandExpressway(PIE), amajormotorwaywithheavytrucktrac (Fig. S2(c) in the ESI). The air pollutants encountered inthe region are expected to be of both particulate and gaseous innature, coming from vehicle emissions and industrial activities.Bottom ash samples from burning joss paper and incense werecollectedimmediatelyaereacheventindierentresidentiallocations in 2012 and 2013 during the Ghost month.2.2 Sample preparationRainwater samples. Samples were collected immediatelyaer therainevent orintheearlymorningfollowingnightprecipitation events. The samples were separated into twoaliquots. An unltered aliquot was used for pH (using Metrohm826 pH meter) and electrical conductivity (EC, using IONcheck30 Conductivity Meter) measurements while the remainingaliquot was ltered through a 0.22 mmcellulose acetatemembranefor ionchromatography andinductively coupledplasma (ICP) measurements.PM2.5, joss paper, incense and bottom ash samples.Collectedsampleswereplacedinmicrowave(MW) digestionvessels, andappropriatereagents(TableS1intheESI)wereadded sequentially. The vessels were capped, placed in the MWsystem, and digested. Aer cooling to roomtemperature,extracts were diluted using ultrapure water,ltered through 0.2mm syringelters and carefully transferred to ICP sample vialsfor elemental analysis. The Emfablters used to collect PM2.5samples were tested to check for the presence of any impurities.The concentrationsof targetelements weremeasured by ICP-MS in solutions of thelter that were digested the same way asthe samples. It was found that thelter materials contributednegligible interference to the analysis.Microwave digestion. Two programmable microwaves(MARS 5, CEMCorp., Matthews, NC, USAandAntonPaarMultiwave PRO, Austria) were used as the closed vessel diges-tion systems. Eective digestions were achieved by setting themicrowave programandpower settings andoptimizingthenature and amount of acids. Standard reference material 2783(SRM2783)ofUrbanParticulateMattersampleswasusedtovalidate the method. The extraction eciencies (determined bythe % recoveries) were >80% for all of the elements present inthereferencematerial. Spikedsampleswereusedtoevaluatethe MW method for bottom ash samples and original joss paperandincense. ThePMandbottomashsamplesweredigestedusing the protocols summarized in the ESI document (Table S1in the ESI).2.3 AnalysisIon chromatography (IC). Cation IC experiments were per-formed with a Dionex ISC-900 utilizing an Ion Pac CS12A 4 mm250 mmanalytical column. For cation IC, the eluentconsistedof 20mMmethanesulfonic acid andthechemicalregenerant consisted of 100 mM tetrabutylammoniumhydroxide. Anion ICexperiments were performed with aDionex ICS-1100 utilizing an Ion Pac AS22 4 mm 250 mmanalytical column. For anion IC, the eluent consisted of4.5mMsodiumcarbonateand1.4mMsodiumbicarbonateand an electrochemical suppressor was used.Inductively coupled plasma. Both inductively coupledplasma-optical emissionspectroscopy (ICP-OES) andinduc-tively coupled plasma-mass spectrometry (ICP-MS) were used toanalyzeacidiedsamplesfortraceelements. Inthersttwoyearsof thisstudyelemental measurementswereperformedwith a Thermo Scientic iCAP 6500 spectrometer in both axialandradical modes. Since the concentrationof some traceelements in samples was not detected by ICP-OES, samples wereanalyzed using an Agilent 7700 series ICP-MS (Japan) equippedwith a 3rd generation He reaction/collision cell (ORS3) tominimize interference fromJanuary 2011. Final optimizedinstrumental operating parameters for this application aresummarizedinTableS2intheESI.Theanalysisofsamplesusing both ICP-MS and ICP-OES helped to test the possibilitiesof potential interference, since the two techniques suer fromdierent interference eects.Data analysis. Data were processed using a Windows basedapplication written in the C# programming language in the .Netplatform. All the statistical tests (arithmetic means, maximumandminimumvalues, standarddeviations, percentiles andmedians) were run with the same application prior to using thedata in graphical plots.3 Results and discussion3.1 Phase IPhase I of this study involvedthe continuous collectionofrainwater and atmospheric PM2.5 samples between August 2009and December2013at theNTU samplingsite(551PM2.5 and574 rainwater samples).Particulate matter. The impact of the Ghost Month onparticulate matter was evaluated by measuring the changes ofthe monthly mean concentrations compared to yearly means foreach element. High haze period data (data from days with PM10>60values)andspecial events(suchasindustrial res)thatwere considered as known pollution sources for a short periodwereexcludedfromthedatasetexceptforafewdaysinyear2012 because of coincidence of the ghost month with the hazeperiod. Statistical data (Table S3 in the ESI) collected from year2010 to 2013 for PM2.5 showed an increase in concentrations formost of the elements during August and September (7th monthof Chinese NewYear) suggesting a strong contribution ofburning events to release particulate matter during the HungryGhost Festival. Table 1 lists dates of the Hungry Ghost Festivaland Ghost Day that occurred during this study.ForPM2.5,themajorelements(Na,Ca,Zn,K,Al,andMg)appeared in concentrations ranging from5 ng m3to amaximumofapproximately50 000ngm3(50mgm3). Theconcentrations of trace elements were found to vary from valuesless thanthe detectionlimit toa maximumof 1 mg m3.Thisjournal isTheRoyal SocietyofChemistry2015 Environ. Sci.:ProcessesImpactsPaper Environmental Science: Processes & ImpactsPublished on 16 July 2015. Downloaded on 14/08/2015 04:32:16. View Article OnlineConcentration time series graphs were examined to nd out theimpactofdierentindustrialandlocaleventsonthecompo-sition of airborne particulate matter at the NTU sampling site. Itwas notable that the percentage concentrations of a largenumber of the elements (listed in Table S3 in the ESI)increased during August and September and this nding was inagreement with rainwater results (see discussion below).ThePM2.5elemental compositiondataindicatedthat theaverage concentrationof many elements during the GhostMonthwashigher thantheirmonthlyandannual averages.TableS4intheESIcontainsacomparisonof theabsolutechemical compositionof PM2.5(mgm3) duringAugust andSeptember (Ghost Month Festival) and the yearly monthlyaverage.Fig. 2 presents data for 9 metals that are listed among the188 hazardous air pollutant substances (HAPS or air toxics)denedundertheCleanAirActAmendmentsof1990(ref.7)(Fig. S3 and Tables S3 and S4 in the ESI include the full list ofthe analyzed elements). Fig. 2 shows that there is a signicantincrease during the Ghost Month from 2010 to 2013 (data for2009havenot beenincludedsincetheyearlyaverageisnotavailable). It canbeseeninFig. 2that themajorityof theincrease inthe elemental compositionoccurredinAugust,except for the year 2012 where the commencement of the Ghostmonth was late. September 2011 experienced the lowest impactsince the ghost month ended in August for this year.In general, the results indicated that Zn, Ca, K, Mg, Fe and Alfollowed by Zr > Ba > Sn > V > NaTiMnCu showed thegreatestpercentageincreaseintheirconcentrations(3460%)while As > W > Sr > Ni > Co > Rb > Cd > Cr > Pb > Mo > Ce > Sbvaried between 18 and 40%. The major health related eects ofinhalation of many of the listed elements (Na, Al, Pb, Cd, Ni andCr) to the lungs, kidney and heart are well known and poten-tially of concern.8According to the fewstudies that have beenperformedregardingtheelemental andorganicconstituentsof incensesmoke produced through burning, it was found that the majorcomponents are inorganic compounds with some carcinogenicelements.5c,9The Lau and Luk study in 2001 was the only liter-ature source that showed joss paper burning released a signif-icant source of elements such as Fe, Cu, Zn and Pb.10Rain. Rainwater that falls in Singapore is collected in localcatchment areas (which comprise two thirds of Singapore's totallandarea) andmakesupapproximately20%of Singapore'swater needs.11Analysis of the rainwater showed that the averagepHvalueover thesamplingperiodwas4.34 0.52(pHofindividual rainwater events ranged from 3.22 to 6.24), with theacidity mainly originating from sulfuric acid levels (45%), andwith a smaller contribution from nitric acid (19%).12The ionicconcentration ofrainwater samplesmeasured by ion chroma-tography (IC) for theve years followed a trend of SO42 > Cl >NO3 for anions and Ca2+> Na+> K+> NH4+> Mg2+for cations.The ions werefoundintheir highest values mostly duringAugust and September. It is noteworthy that the concentrationofMg2+increasedsignicantlyandthecationorderchangedtoCa2+>K+>Na+Mg2+>NH4+fortheAugust/Septemberperiod. Elemental analysis of the rainwater samples by ICP-OESand ICP-MS showed the same trend for the August/Septemberperiods. Zn, Ca, K, Mg, Fe and Al were the major elements fol-lowed by Sn > V > NaMnTiCu > As > W > Ni > Co > Cd >Cr > Pb.The results indicated that substantial increase in theconcentration of ionsand elementsin rainwatersamples wasobserved in the beginning, mid and at the end of Ghost monthforall yearswhichcanbeassignedasduetoburninglargeamount of joss paper andincensethroughout Singapore(astrong fragrant smoke smell pervades during these days).Fig. 3 displays theuctuation of concentration of the majorioniccomponentsof rainwatersamplescollectedduringtheGhost month. The red vertical lines in Fig. 3 correspond to the1st, 15thandnal dayof theGhost monthforeachyearasTable 1 Ghost Festival and Ghost Day from 2009 to 2013Year Hungry Ghost Festival Ghost Day2009 20 Aug18 Sep 2 Sep2010 10 Aug7 Sep 24 Aug2011 31 July28 Aug 14 Aug2012 17 Aug15 Sep 30 Aug2013 7 Aug4 Sep 20 AugFig. 2 Percentage increase in the elemental chemical composition ofPM during August and September (Ghost month festival).Environ. Sci.:ProcessesImpacts Thisjournal isTheRoyal SocietyofChemistry2015Environmental Science: Processes & Impacts PaperPublished on 16 July 2015. Downloaded on 14/08/2015 04:32:16. View Article OnlineFig. 3 Concentration proles of rainwater chemical composition during the Ghost Month Festival.Thisjournal isTheRoyal SocietyofChemistry2015 Environ. Sci.:ProcessesImpactsPaper Environmental Science: Processes & ImpactsPublished on 16 July 2015. Downloaded on 14/08/2015 04:32:16. View Article Onlineindicated in Table 1. The highest concentration was observed inrain events aer the 1st, 15th and end day of the Ghost monthduetomassiveburningof josspaper andincenseinthosespecialdays. However, therelationshipbetweenprecipitationevents and the Hungry Ghost Festival is complicated because,unlike the PM2.5 data which are collected continuously, the rainfrequency does not necessarily perfectly match the days with thehighest burning. Nevertheless, the high frequency of rain eventsinSingaporeintheAugustSeptemberperiodoverthe5yearperiod did indicate that there is a notable correlation betweenan increase in the ionic concentration of the precipitation andthe major burning events (Fig. 3).Theconcentrationsofcationsandanionsbothfellsigni-cantlyaerthe rst orsecondrainevent. Thehighest ionicconcentrations were measured during the Ghost month in 2012because of the coincidence of the Ghost month and the trans-boundary haze period. Na+and Ca2+are present in much higherconcentrations inthecationconcentrationprole, whileK+shows a higher concentration as an index of biomass burning inyear 2012. Mg2+also shows a high concentration during theseevents.It canbe seenfromthe plots inFig. 3that there weredierencesintheabsoluteconcentrationsofionsdetectedinthe rainwater from year to year, which is likely to occur due totwomajorreasons. Firstly, thebackgroundlevelsintherainsamples can vary due to local industrial events unrelated to theHungry Ghost Festival as well as from transboundary pollutionfrom Indonesia or Malaysia. Secondly, the quantities of mate-rials released into the atmosphere each year due to the festivalburning are not the same andwill vary depending onthenumberof res, thequantitiesof materialsburnt, theexactlocations of the re pits, the period of time that ash is le beforeclean-up, andtheexactmeteorological conditions. Therefore,the absolute concentrations are less signicant than thepercentageincreaseobservedduringthetimesofburningforboth the PM2.5 as well as the rain samples.3.2 Phase IIThesecondphaseofthisprojectwascommencedinJanuary2011 to determine the elemental chemical composition of theunburnt and burnt (bottom ash) samples from joss paper andincensecollectedduringtheGhostmonthinordertofurtherinvestigate the link with the annual spikes in pollution in theAugust/September period (compared to the yearly averages).Incense and joss paper analysis (unburnt). Prior to theanalysis of bottom ash samples, the elemental composition ofthe unburnt incense and joss paper commonly used during theghost monthfestival was determined. TableS5intheESIprovides the distribution of the elements for dierent types ofjosspaper andincense. FromthedatainTableS5(a)it isapparent that the Ca content is the highest in the unburnt josspaper and incense. Generally, the elemental composition orderfor the unburnt joss paper samples is Ca > Al > Na > Mg > K > Fe> Ti > Ba/Cu > Sr > Ga/Zn > Mn > Sn > Mo > Zr > Pb > Cr > V > Co >Ce > Ni > La > Y > As > Rb > Nd > Cd > Sc > Pr > W > Sb > Se > Cs >Hg while the elemental composition for unburnt incense is Ca >K > Al/Fe > Mg > Na > Mn > Ba > Ti > Sr > Zn > Rb > Ga > Cu > Pb >Cr > V > Ce > Ni > W > As > Nd > Y > Co > Cs > Hg > Sn > Cd > Sc >Se > Sb. These results indicate that aer Ca, K has the higheraverage composition in incenses while Al has the higher averagecomposition in joss paper.Hsueh et al.13studied the composition (Na, Ca, Mg, Al, K, Fe,Cu, Pb, Sr, MnandZn) andthedistributionof theemittedparticles (aerodynamic diameter 0.01100 mm) during theburning process of joss paper. Their results showed thatelements were partly released in emitted particles mostly in theform of PM2.5 (>70% for Na, Al, Pb, and Cu) and smaller parti-cles. Fang et al.3calso demonstrated that thener particulates(PM2.5) make up the majority of emitted particulates in temples.Accordingtothese ndingsandthelist of theelementspresentedinthisstudy, thecompositionof theparticulatematter generatedfromjoss paper andincense burning isalarming. In addition, it has been reported that the presenceof transition metals (Cu, Fe and Zn) which might act as cata-lysts increase the formation of some organic chemicals suchas polychlorinated dibenzo-p-dioxins (PCDDs) and poly-chlorinated dibenzofurans (PCDFs).14Bottom ash from the burnt incense and joss paper. Bottomash samples are the solid product remaining from the burningprocess of joss papers and incense. It can be seen from TableS5(b) inthe ESI that the trend inthe metallic chemicalcompositionof the bottomashfromburnt joss paper andincense is similar to that observed for the unburnt joss paper.Hsueh et al.13showed that most of the elements released aerburning of joss paper are also present in the bottom ash.It can be seen in Table S5(b) that there are some dierencesin the transition metal content (such as Sn, Pb, Cr, Ni and W)betweenthe dierent joss paper bottomashsamples. Thiscomposition dierence is likely related to the varying texturesandthepaintthatareusedinthedierenttypesofthejosspapers. Lau and Luk concluded that the pollution compositionvaried depending on the exact type of the joss paper.10Analysisof bottomashdatafromincensesindicatedthatincense No. 3 showed higher concentrations of Ba, Cu, Sr, Ga,Zn, Mn and W than the other samples. From Table S5(b) in theFig. 4 Recoverytest for bottomash( ) andunburnt original ( )of JP7.Environ. Sci.:ProcessesImpacts Thisjournal isTheRoyal SocietyofChemistry2015Environmental Science: Processes & Impacts PaperPublished on 16 July 2015. Downloaded on 14/08/2015 04:32:16. View Article OnlineESI, it can also be concluded that the incense bottom ash haslower concentrations of Cu, Zn, Pb, Cr and Co than the bottomashfromjosspapers, whileMn, Ni andAswerepresent inhigher concentrations than the bottom ash from joss papers.SincethereisnotanyCertiedReferenceMaterial (CRM)available for paper/cardboard, recovery tests were performed forboth bottom ash and unburnt joss paper and incense to validatethe method. An identical trend was observed for various types ofjoss paper and incense. Table S6 in the ESI shows the recoveryfor dierent types of joss paper and incense that varies from 68to 98% and from 79 to 123% for bottom ash and unburnt josspaperandincense,respectively.Fig.4showsarepresentativeFig. 5 Concentration proles of bottom ash samples collected during the Hungry Ghost Festival in years 2012 and 2013 in dierent parts ofSingapore.Thisjournal isTheRoyal SocietyofChemistry2015 Environ. Sci.:ProcessesImpactsPaper Environmental Science: Processes & ImpactsPublished on 16 July 2015. Downloaded on 14/08/2015 04:32:16. View Article Onlineexample for bottom ash of joss paper (JP7) which shows that therecovery is oen less than 90%, with Na, K and Cr having thelowest recovery. Hsueh et al.13suggested that bottomashdigestion is more dicult than digesting the unburnt materialbecause of the strong post burning binding energy.Bottomash samples collected fromburning events. 7bottomashsampleswerecollectedduringtheHungryGhostFestival fromburning containers in dierent parts of Singapore.Fig. 5 gives the comparison of the chemical composition of the 7collectedbottomashsamples. Notably, aswell asthemajorelements, all of the trace elements including the HAPS listed inFig. 2 were detected in the burnt and unburnt incense and josspaper samples. The elemental contents were categorized into 5groups according to their concentration range.(a) Ca was present in the highest amount (high mg g1).(b) Al, Mg, NaandFe were present inthe next highestconcentrations (mg g1).(c) KandTi werethemajorelementsinthethirdgroupfollowed by Ba, Zn, Sr, Cu and Mn. Surprisingly Sn showed veryhighconcentrations(400mgg1) forthe rst twosampleswhilefortherestofthesamplestheSnconcentrationvariedfrom 11 to 40mg g1, which likely relates to dierent types ofjoss paper and incense that were used for burning.(d) The concentrations of Pb, Co, V, Ni, La, Rb, Nd, Ba, Y, Th,Sc, Mo, Pr, Hf, As, In and Sb were less than 25mg g1and areconsidered as the moderate concentration.(e) The last grouphas beenlistedas lowconcentrationelements (ng g1) including Gd, Sm, W, Ir, Ge, U, Dy, Hg, Eu, Be,Bi, Er, Se, Yb, Tb and Ho.As part of an eort to preserve racial and religious harmonyin multicultural Singapore, the National Environmental Agency(NEA) provides burning pits and containers to encourage peopleto burnjoss papers andincense sticks responsibly duringfestivals. Frequently, thedesignatedcontainersprovidedarenot sucient andpeopleresort toburningjosspapersandincense sticks on the pavements, grass elds or commoncorridorsat thegroundlevel neartheirresidential highrisebuildings.However cleaners are also deployed to clear up the residualashes in the neighbourhood on a daily basis; although in someareastheashesareleinsidethecontainersfor thewholemonth and are blown by the wind. These ashes are treated asnormal waste and are disposed in either in incinerators or in anoshore sanitary landll where the components can penetrateinto the groundwater.15Unfortunately, some people believethatdrinkingaslurryofburnedjosspapermixedwithwater(waterisaddedtobottomash)canbeusedtocurediseases,protect themselves, rejuvenatetheir relationships andotherremedies.163.3 Ti Kong Dan Day and Ching Ming FestivalAninspectionofthedatasetshowedthatasimilarpatternofincrease in the metallic composition in both particulate matterand rain water samples was observed for Ti Kong Dan Day (9thdayofChineseNewYear, birthdayoftheJadeEmperor)andChing Ming Festival (on the 104th day aer the winter solsticeor the15thdayfromtheSpringEquinox, usuallyoccurringaroundApril4th or5th oftheGregoriancalendar)sinceresi-dentsfollowthesamecustomof makingburningoerings.However, duringthesetwoeventstheburningmainlytakesplace infurnaces of thetemples. While alarge amount ofcombustion occurs, the impact is much lower than the HungryGhostFestivalbecausetheburningoccursinclosedfurnacesequipped withltration systems.4 ConclusionsA ve year continual investigation of rainwater and atmosphericPM2.5indicatedconsistentlyhigher concentrationsfor manyelements during August and September, which can be linked totheextensiveoutdoor burningevents that occur duringtheHungry Ghost Festival. The individual elements detected in thePM2.5 over the Hungry Ghost period were 1860% higher thanthose of the average background.In general, Ca is present in the highest concentration in theunburnt joss paper followedby Al. For incense, Cais alsopresent in the highest concentration followed by K. Theconcentrationof Cu, Zn, Mn, Mo, Pb, Cr, V, Co, Ni andCductuatedinthedierent types of joss paper andincense,presumably according to the rawmaterial and productionprocess. Thechemical compositionandtheorderofconcen-tration of the elements detected in the bottom ash of the burntjosspaperandincensearesimilartothoseobservedfortheunburnt joss paper and incense.A major conclusion of this study is that the pollutiongenerated by open burning of joss paper and incense requiresmore attention. There is currently a lack of corroboratinginformation about the impact on air quality and air pollutantsemitted from open burning of joss paper and incense burning.Furthermore, there are limited literature reports of evidence forepidemiological links betweenrespiratory disease andskinallergies and burning of incense and joss paper in an indoor oroutdoor environment. However, unocially it has been repor-ted that a greater number of patients during this festival periodseek treatment for ailments such as asthma, eye irritation, andnasal and skin allergies.17Inorder torespect religiouspracticesandnot todisturbdevotees (pilgrims) bottom ash samples were collected aer thefestivals. However, it is believed that in order to better investi-gate the healtheects caused by inhalationof particulatematter emitted from burning; the sampling would preferably becarried out in the festival venues at the same time.Burningjosspaperandincensehasbeenpartofreligiousceremonies for thousands of years but some regulatory moni-toring may be required to control air and water pollution andreducethehealtheects for thegreater goodof theentirepopulation. This issue needs government agencies, templeboards, religious leaders, research scientists and privatermsworking together to reduce the pollution as much as possible.With the utmost respect to this religious practice the concern isabout the control of the pollution and care of devotee's health.Possible solutions have been proposed, including thefollowing:Environ. Sci.:ProcessesImpacts Thisjournal isTheRoyal SocietyofChemistry2015Environmental Science: Processes & Impacts PaperPublished on 16 July 2015. Downloaded on 14/08/2015 04:32:16. View Article Online(a) Increased public education on air quality and thecomposition of bottom ash (especially if ingested as a slurry).(b) Providing closed furnace with a ltering systeminconvenient areas.(c) Using eco-friendly materials for production of joss paperand incense and control of the production process.AcknowledgementsThis work was supported by the Singapore GovernmentMinistry of Education AcRF Tier 1 research grant (RG 61/11), theSingapore Ministry of Defence-NTU Joint programme (MINDEF-NTU/JPP/12/02/04) grant and the National Research Foundationof SingaporeunderitsCampusforResearchExcellenceandTechnological Enterprise (CREATE) programme.References1(a) J. J. Schauer, M. P. Fraser, G. R. Cass andB. R. T. Simoneit, Environ. Sci. Technol., 2002, 36, 38063814; (b) M. Zheng, R. G. Cass, J. J. Schauer andE.S.Edgerton, Environ. Sci. Technol.,2002, 36,23612371;(c)A. Cincinelli, S.Mandorlo, R. M. DickhutandL. Lepri,Atmos. Environ., 2003, 37, 31253133; (d) C. A. Pope, AerosolSci. Technol., 2000, 32, 414; (e) C. I. Davidson, R. F. Phalenand P. A. Solomon, Aerosol Sci. Technol., 2005, 39, 737749.2(a)J.N. Galloway,G. E.LikensandM.E.Hawley, Science,1984, 226, 829831; (b) J. L. Moody, A. A. P. Pszenny,A. Gaudry, W. C. Keene, J. N. GallowayandG. Polian, J.Geophys. Res., 1991, 96, 769786; (c) F. L. T. Gonalves,M. F. Andrade, M. C. Forti, R. Astolfo, M. A. Ramos,O.MassambaniandA.J.Mel,Environ.Pollut.,2003,121,6373; (d) P. R. Salve, A. Maurya, R. Sinha, A. G. GawaneandS. R. Wate, Bull. Environ. Contam. Toxicol., 2006, 77,305311; (e) A. Malik, V. K. SinghandK. P. Singh, Bull.Environ. Contam. Toxicol., 2007, 79, 639645; (f)Y. W. F. ThamandH. Sakugawa, Bull. Environ. Contam.Toxicol., 2007, 79, 670673.3(a) C. S. Li and Y. S. Ro, Atmos. Environ., 2000, 34, 611620; (b)C. W. Fan and J. J. Zhang, Atmos. Environ., 2001, 35, 12811290; (c) G. C. Fang, C. N. Chang, Y. S. Wu, C. J. Yang,S. C. ChangandI. L. Yang, Sci. Total Environ., 2002, 299,7987.4(a) H. H. Yang, R. C. Jung, Y. F. Wang and L. T. Hsieh, Atmos.Environ., 2005, 39, 33053312; (b) C. C. Lin, S. J. Chen,K. L. Huang, W. J. Lee, W. Y. Lin, J. H. Tsai andH. C. Chaung, Environ. Sci. Technol., 2008, 42, 42294235;(c) M. D. Lin, J. Y. Rau, H. H. Tseng, M. Y. Wey, C. W. Chu,Y. H. Lin, M. C. Wei and C. H. Lee, J. Hazard. Mater., 2008,156, 223229; (d) S. C. LungandS. C. Hu, Chemosphere,2003, 50, 673679; (e)T. C. Lin, F. H. Chang, J. H. Hsieh,H. R. Chao and M. R. Chao, J. Hazard. Mater., 2002, 95, 112; (f) G. C. Fang, Y. S. Wu, M. H. Chen, T. T. HoandJ. Y. Rau, Atmos. Environ., 2004, 38, 33853391.5(a) R. Caggiano, M. D'Emilio, M. Macchiato and M. Ragosta,Environ. Monit.Assess.,2005, 102,6784;(b)F.Eldabbagh,A. Ramesh, J. Hawari, W. Hutny and J. A. Kozinski,Combust. Flame, 2005, 142, 249257; (c) G. C. Fang,C. N.Chang, C. C. Chu,Y. S.Wu, P.P. C. Fu, S.C. Changand I. L. Yang, Chemosphere, 2003, 51, 983991; (d)O. W. LauandS. F. Luk, Atmos. Environ., 2001, 35, 31133120.6B. Wang, S. C. Lee, K. F. HoandY. M. Kang, Sci. TotalEnviron., 2007, 377, 5260.7http://www.epa.gov/airtoxics/orig189.html.8(a) M. Costa, Human Exposures and Their Health Eects, ed.M. Lippmam, JohnWiley&Sons, Inc, Hoboken, NJ, USA,2nd edn, 2000, pp. 811850; (b) S. G. Donkin, D. L. Ohlson,C. M. Teaf, Propertiesandeectsof metals, Principles oftoxicology: environmental andindustrial applications, ed. P.L. Williams, R. C. JamesandS. M. Roberts, JohnWiley&Sons,Inc,Hoboken,NJ,USA,2ndedn,2000,pp.325344;(c) M. E. Gerlofs-Nijland, M. Rummelhard, A. J. F. Boere,D. L. Leseman, R. Dun, R. P. F. Schins, P. J. A. Borm,M.Sillanpaa,R.O.SalonenandF.R.Cassee, Environ. Sci.Technol.,2009, 43,47294736; (d)S.K.Park, M. S.ONeill,P. S. Vokonas, D. Sparrow, R. O. Wright, B. Coull, H. Nie,H. Hu and J. Schwartz, Epidemiology, 2008, 19, 111120.9(a) R. E. Rasmussen, Bull. Environ. Contam. Toxicol., 1987, 38,827833; (b) C. Y. Mimi, D. H. Garabran, T. B. HuanandB. E. Henderson, Int. J. Cancer, 1990, 45, 10331039.10O. W. LauandS. F. Luk, Atmos. Environ., 2001, 35, 31133120.11(a) C. Tortajada, Int. J. Water Resour. Environ. Eng., 2006, 22,227240; (b) I. O. B. Luan, Int. J. Water Resour. Environ. Eng.,2010, 26, 6580.12B. Khezri, H. Mo, Z. Yan, S.-L. Chong, A. K. Heng andR. D. Webster, Atmos. Environ., 2013, 80, 352360.13H. T. Hsueh, T. H. Ko, W. C. Chou, W. C. Hung and H. Chu,Environ. Chem. Lett., 2012, 10, 7987.14M.T.Hu,S.J.Chen,Y.C.Lai,K.L.Huang,G.P.Chang-Chien and J. H. Tsai, Aerosol Air Qual. Res., 2009, 9, 369377.15(a) J. Robson, Hist. Religions, 2008, 48, 130169; (b) Taoism,ed. Z. Mou, (Trans: J. Pan, S. Normand), Leiden [TheNetherlands], Boston, Brill, 2012, pp. 293308.16(a) http://app2.nea.gov.sg/energy-waste/waste-management/overview; (b) http://app2.nea.gov.sg/energy-waste/waste-management/solid-waste-management-infrastructure.17http://www.healthxchange.com.sg/News/Pages/More-ailments-during-Hungry-Ghost-Festival.aspx.Thisjournal isTheRoyal SocietyofChemistry2015 Environ. Sci.:ProcessesImpactsPaper Environmental Science: Processes & ImpactsPublished on 16 July 2015. Downloaded on 14/08/2015 04:32:16. View Article Online