PROCEEDINGS. Executive Summary. on Air Pollution and Public Health. May 23 and 24, 2002 Montréal

Transcription

1 PROCEEDINGS Executive Summary n Air Pllutin and Public Health May 23 and 24, 2002 Mntréal

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3 PROCEEDINGS OF THE SYMPOSIUM ON AIR-POLLUTION AND PUBLIC HEALTH Executive Summary Mntréal, May 23-24, 2002 Held under the auspices f the Cnference f New England Gvernrs and Eastern Canadian Premiers Prepared by: Gvernment f Québec August, 2002

4 Sympsium n Air-pllutin and Public Health Executive Summary Thrughut New England and sutheastern Canada, air-pllutin levels, especially thse f zne and particulate matter, cmmnly exceed US and Canadian ambient air-quality limits. On high-pllutin days, millins f individuals are expsed t pllutants that can reduce respiratry functin in the healthy, exacerbate respiratry symptms in thse wh are ill, trigger asthma attacks, increase hspital admissins related t cardivascular and respiratry diseases, and result in premature death. These acute effects are assciated with shrt-term peaks in air-pllutin levels, and have been dcumented in studies invlving mre than 100 US and Canadian cities. Lng-term expsure t air-pllutin has been shwn t reduce lngevity, particularly thrugh the develpment f lung cancer r cardipulmnary disease. Several extensive prspective studies shw that even relatively small differences in fine particle cncentratin measured in different Nrth American cities are assciated with significant differences in health effects. During the tw-day sympsium n Air-pllutin and Public Health, rganised by the Gvernment f Québec under the auspices f the Cnference f New England Gvernrs and Eastern Canadian Premiers, scientists frm the United States, Canada, and Eurpe described recent advances in their respective areas f expertise and suggested specific actins t reduce airpllutin and its impact n human health. These recmmendatins have been cmpiled in a list f recmmendatins, which is presented at the end f this summary. Scientific debate surrunding a number f imprtant issues is nging. Nnetheless, researchers and public health prfessinals attending the sympsium strngly supprted tw majr cnclusins. First, the current evidence fr increased illness and mrtality due t air-pllutin is bth substantial and cmpelling. Secnd, mre extensive interventin by federal, state and prvincial gvernments, in the frm f mnitring, research funding and cncrete plicy actin, are necessary t prtect public health. Air-pllutin levels and surces in nrtheastern America Air-pllutin is a cmplex mixture f substances f varying txicity. Hwever, tw pllutants -- fine particulate matter (PM 2.5 ) 1 and zne (O 3 ) -- are assciated with well-knwn cardirespiratry health prblems fllwing expsure t cncentratins cmmnly fund in urban areas, and were the fcus f many presentatins at this sympsium. Bth zne and fine particulate matter are referred t as secndary pllutants as they are frmed in the air by directly emitted primary pllutants such as sulphur dixide, nitrgen xide, ammnia and hydrcarbns. In additin, fine particulate matter is a primary pllutant emitted directly during gasline, diesel, and wd cmbustin, and thrugh fine dust suspensin. In eastern Canada, fine particulate matter and zne levels ften exceed natinal standards, with zne levels exceeding the standard mre frequently and by a greater margin than particulate matter. 1 Fine particulate matter r PM 2.5 is defined as particulate matter with a diameter less than 2.5 µm. Carse particulate matter r PM 10 is defined as particulate matter with a diameter less than 10 µm. 3

5 In the United States, the EPA prmulgated new Natinal Ambient Air Quality Standards fr fine particulate matter and zne in On the basis f data cmpiled between 1997 and 2000, 407 cunties lcated thrughut the nrtheastern US, with a cumulative ppulatin f 136 millin, are likely in vilatin f the PM 2.5 standard, and/r the O 3 standard. Bth pllutants have lng lifetimes, resulting in their lng-range transprt away frm emissin surces, which in turn increases the prprtin f the expsed ppulatin. In rder t develp an air-pllutin reductin strategy, it is essential t understand the relatinship between emissins and their effects n a particular receptr lcatin. In recent years, new mdelling methds, knwn cllectively as receptr mdelling, have been develped t assist regulatrs in identifying surces and the apprtinment f the bserved pllutant cncentratins t thse surces. Receptr mdels fcus n the envirnment at the pint f impact, identify different aersl cmpnents and trace likely pathways back t the prbable surces. Receptr mdelling is a tl fr lcating surces cntributing t O 3 r PM 2.5 episdes. Fr example, the highest O 3 and PM 2.5 levels in suthwestern Québec are assciated with pllutants travelling frm the midwestern US and acrss suthern Ontari. Findings at a mnitring site in nrthwestern Vermnt shw that the majr cntributin t PM 2.5 riginated frm cal cmbustin activities in the midwestern U.S. In winter, lcal residential wd cmbustin (in nrthern New England and suthwestern Québec), was als fund t cntribute significantly. The relative cntributins f specific air-pllutin surces t individual expsure In epidemilgical studies f the health effects f air-pllutin, ambient air data are used extensively t estimate individual expsure t pllutants. Hwever, in many cases ambient air cncentratins may be a pr surrgate f actual expsures f individuals t particular pllutants, especially when surces such as envirnmental tbacc smke, heavy rad-vehicle traffic, r residential wd cmbustin, are dminant. Fr example, in varius lcalities in the regin, including majr cities such as Mntreal, smke frm wd burning in winter is a majr surce f fine particulate matter. A feasibility study carried ut in tw Mntreal neighburhds, characterised by high and lw use f wd fr heating, shwed that indicatrs ther than ambient particulate matter, such as the cncentratin f particular cntaminants in indr air r pllutin-related substances in urine, culd be used effectively within an epidemilgical study t discriminate amng neighburhd wd cmbustin, husehld wd cmbustin, and smking. Assessing expsure t vehicle emissins remains a challenge, as existing mnitring netwrks in urban areas generally measure urban air-pllutin frm multiple surces. They are nt designed t assess specifically within-city spatial variability resulting frm differing traffic patterns. In the past, simple surrgate expsure measures, such as distance f a residence frm a majr rad r the presence f a highway in a district, have been used t categrise expsures in epidemilgical investigatins. Hwever, these appraches, and even mre sphisticated methds that incrprate dispersin mdelling, are limited by a shrtage f mnitring statins near majr radways, as well as uncertainty regarding vehicle emissin rates. 4

6 T refine the assessment f vehicle-related expsure, researchers are nw applying gegraphical infrmatin system (GIS) mdelling t estimate ambient cncentratins within the cntext f epidemilgical studies and risk assessments. In these studies, measured air pllutant cncentratins and gegraphical variables (e.g. lcatin f majr rads, traffic-flw data) are cmbined in the GIS-based mdel in an effrt t better estimate individual expsures. Envirnmental studies ver the past tw decades have shwn that the mst imprtant surces f expsure t many txic air pllutants are lcated indrs, where we spend mst f ur time. Using cancer risk as a criterin, the air txics f greatest cncern are envirnmental tbacc smke (ETS), radn, benzene, chlrfrm, and para-dichlrbenzene. These txic substances are predminantly released frm indr rather than utdr surces, with the exceptin f benzene, which is emitted int the atmsphere primarily by mtr vehicles and industrial facilities. Mrever, pllutants released indrs are far mre likely t be inhaled than pllutants released utdrs. Fr example, the benzene in ETS is respnsible fr a greater prprtin f human expsure t benzene than is all statinary industry in the US. T date, all three natinal task frces mandated with setting envirnmental pririties have designated indr air expsure as high pririty. Mrever, they all recgnise the absence f a specific agency t regulate indr air-pllutin. The US EPA is currently spnsring fur majr studies int indr air-pllutant expsures f individuals at high risk fr cardivascular and chrnic bstructive pulmnary disease. The results f these studies will be presented in August Persnal, indr and utdr mnitring f PM 2.5, PM 10 and assciated gases (SO 2, NO 2, CO) was carried ut fr 10 t 14 days per persn, ver 2 t 4 seasns. The gal f these investigatins was t relate persnal expsures, primarily indr surces, t ambient expsures. Shrt and lng-term health effects f air-pllutin Within the cntext f epidemilgy, the challenge f identifying the health effects f air-pllutin has been apprached frm tw very different angles: extensive chrt studies in which individual subjects are fllwed ver many years, and time-series studies, in which shrt-term changes in daily mrtality (r hspital admissins) are cmpared with shrt-term changes in ambient airpllutin. The cnsistency f the findings, shwing increased cardipulmnary illness and mrtality assciated with higher air-pllutin levels, especially higher fine particulate matter levels, has led the public health cmmunity t cnclude that the relatinship is cause and effect. Epidemilgical data frm lng-term fllw-up studies f chrts f individuals living in varius areas f the United States (the Harvard Six City Study, the American Cancer Sciety Study, the Califrnia Adventist Health Study f Smg) are supprted by retrspective studies in Eurpe assciating the incidence f cancer with expsure t traffic-related ambient air-pllutin. The quantitative results frm these studies are fairly similar and shw, fr example, an increased risk f lung cancer f at least 10 t 20% fr a relatively small increase f 10 µg/m 3 in fine particulate matter level. With respect t shrt-term effects, much f the evidence cmes frm multi-city studies f assciatins between shrt-term expsures and mrtality. These investigatins, carried ut ver the past 5 t 10 years, cnsistently indicate increased mrtality n days when there is a sharp increase in particulate matter levels. Fr example, in the analyses f data frm a 6-city US study and an 8-city Canadian study, an increase in daily mrtality f 3 t 4% was assciated with a daily increase f 25 µg/m 3 ver the nrmal ranges f fine particulate matter, which is generally belw 20 µg/m 3. 5

7 In the case f zne, the clearest evidence that current ambient zne levels are clsely assciated with health effects in human ppulatins cmes frm epidemilgical studies f acute respnses, including bservatins f increased emergency hspital admissins fr asthma and ther respiratry diseases. On the basis f the expsure-respnse relatinship bserved in New Yrk City, fr example, it has been estimated that reductins in zne t the level f the new standard (80 ppb) wuld annually prevent 2,000,000 acute respiratry symptms, 930,000 restricted activity days, 180,000 asthma attacks, 3,500 respiratry Emergency Department visits, 265 asthma hspital admissins, 240 admissins due t ther respiratry diseases, and 75 deaths. Cntrlled txiclgical studies, in bth human subjects and experimental animals, prvide crucial supprt t the epidemilgical findings. These investigatins can determine the physilgical mechanisms fr adverse health utcmes, identify bimarkers fr assessing expsure, and cntribute t a far greater understanding f the relatinship between expsure and risk, bth fr healthy individuals and mre vulnerable individuals in the ppulatin. With regard t fine particulate matter, txiclgical studies have identified elevated prductin f endthelins in bth humans and animals as a respnse t expsure t urban air particles. Endthelins have been implicated in heart disease, kidney failure, vascular dysfunctin, athersclersis, diabetes, and ther diseases. The identificatin f such a critical endpint will allw many future avenues f experimental research, such as, the respnse in experimental animals t particles f different chemical cmpsitin. With respect t the develpment f science-based plicy, an imprtant questin addressed by this sympsium cncerned using type f expsure -- lng-term r shrt-term -- fr setting particulate matter standards. In many Eurpean cuntries, standards are based n yearly averages, and airpllutin reductin strategies fcus n reducing the lng-term average. In the US, althugh bth 24-hur and annual standards fr fine particulate matter have been prmulgated, attainment f the annual standard is mre difficult and, therefre, it is the mre critical value. In Canada, nly a 24- hur standard fr fine particulate matter has been prmulgated, which appears t reflect a greater emphasis n shrt-term risks. The imprtance f harmnising the differing US and Canadian standards fr bth New England and eastern Canada was emphasised by several participants. The relatinship between asthma and air-pllutin Asthma is a chrnic lung disease ccurring in bth children and adults, in which airways narrw due t inflammatin and brnchspasm (squeezing f the smth muscle surrunding the airways). The inflammatin leads t epithelial damage including brnchial wall thickening and structural changes f the airways. This cmplex interactin causes symptms f cugh, chest tightness, shrtness f breath, and wheezing. Asthma rates are rising. Data frm the Centers fr Disease Cntrl shw a dubling in US asthma cases frm 6.8 millin in 1980 t 14.6 millin in 1996, with a further increase t 17.3 millin in While there is sme questin that changes in the definitin f asthma and pssibly higher diagnsis rates may accunt fr sme f the increase, there is little dubt that this upsurge is real. Asthma deaths in the US tripled frm 1,674 in 1977 t 5,438 in 1998 making asthma the leading cause f death in yung children. Causes fr this epidemic are unknwn, althugh changes in frequency and severity f early childhd infectins, besity, and expsure t indr allergens and t indr and utdr air pllutants have all been linked t asthma. 6

8 A recent investigatin in Hamiltn, Ontari, an industrial city with a high prevalence f asthma, examined the rle f air-pllutin within the cmmunity as a determinant f the disease. Gegraphical statistical techniques and mnitring data were used t assess variatins in pllutant levels within the city. The study fund that chrnic expsure t industrial air-pllutin is significantly assciated with asthma prevalence, and expsure t traffic pllutin was assciated with asthma in wmen. Inflammatin f the airways may be caused by aerallergens, such as pllen grains and fungal spres, which have been the cause f dramatic epidemics in the exacerbatin f asthma symptms. Mre recent evidence pints t subtler respiratry effects, similar in magnitude t thse assciated with ambient air-pllutin. Furthermre, a number f pssible mechanisms have been identified thrugh which air pllutants and aerallergens may interact, including carriage f allergenic material frm pllen n diesel particles, alteratin f bilgical activity f aerallergens by air pllutants and amplificatin f allergic respnses fllwing expsure t air pllutants. Aerallergens and air pllutants may als behave similarly in respnse t meterlgical factrs. While aerallergens are nt strictly anthrpgenic, human activities can have imprtant psitive and negative influences n levels f human expsure, thrugh ragweed cntrl, fr example. Therefre, there are bth practical and health-related advantages t addressing the adverse effects f aerallergens and urban air-pllutin tgether. Recmmendatins fr the Cnference f New England Gvernrs and Eastern Canada Premiers The recmmendatins cmpiled n the basis f individual presentatins and the plenary sessin f the sympsium have been classified under three headings: imprving the air-quality database, epidemilgical and txiclgical research requirements, and cncrete individual and gvernmental interventin t reduce air-pllutin-related health impacts. Imprving the air-quality database A substantial increase in Canada's investment in ambient air mnitring, in rder t increase bth the number f sampling sites and the frequency f data cllectin; this was ne f the highest-ranked pririties fr immediate actin, as withut adequate mnitring data, high-quality health studies cannt be carried ut, standards cannt be implemented, and the case fr cncrete actins and behaviural changes cannt be made; Mre extensive radside mnitring f air-pllutin, t better characterise this fractin f urban air-pllutin; Imprved databases fr emissin inventries. Epidemilgical and txiclgical research needs Initiatin f an extensive chrt study n children, similar t the suthern Califrnia children s prject; 7

9 Imprved expsure assessment, particularly as it relates t specific surces. This is imprtant in rder t develp plicies targeting surces respnsible fr the greatest health impact. Lng-term gvernment cmmitment t funding envirnmental health research; Cllabratin between nn-gvernment and gvernment researchers, as well as database sharing; Renew the Canadian Txic Substances Research Initiative, which was cancelled this year and prvide it with additinal funding t study transbundary pllutin; Clarify the relatinship between indr and utdr pllutin levels. Cncrete interventin t reduce air-pllutin-related health impacts Adptin f Canada-wide PM and zne standards by prvincial gvernments; Public educatin, with messages emphasising the serius health cnsequences f airpllutin; Daily frecasts f particulate matter, zne, and pssibly pllen. This infrmatin, transmitted t the public, culd help mre sensitive individuals reduce strenuus activities n high-pllutin days; Supprt fr ragweed cntrl prgrams; Cnverting city and schl buses t cmpressed natural gas. Diesel buses represent a surce f fine particulate matter emitted in breathable airspace; Increased participatin by the health cmmunity, including public health advcacy grups such as the Lung Assciatin, in develping air-pllutin reductin prgrams and plicies; where necessary, adpting lcal by-laws t cntrl residential wd burning; Incentives fr marketing fuel-efficient cars; Enfrcement f anti-idling by-laws (< 4 minutes fr statinary vehicles); Mandatry autmbile inspectin prgrams; 8

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11 n Air Pllutin and Public Health This paper cntains 30 % f pstcnsuming recycled fibers. 4716A-02-08