health effects of air pollution in canada: expert panel

REVIEW

Health effects of air pollution in Canada: Expert panel findings for

The Canadian Smog Advisory Program

DAVID M STIEB*t MD MSc CCFP FRCPC, L DAVID PENGELLYt+ PhD, N INA ARRON* BScPHN MHA,

S MARTIN T AYLORt§ PhD, MARK E RAIZENNE* BSc

*A ir Quality Health Effects Research Section, Health Canada, Ottawa, tJnstitute of Environment and Health. McMaster University and University of Toronto, +Departments of

Medicine and Engineering Physics, McMaster University, Hamilton, §Department of Geography, McMaster University, Hamilton. Ontario

OM STIEU, LO PE GELLY, N ARRON, SM TAYLOR, ME R AIZF.N E. Health effects of air pollution in Canada: Expert panel findings for The Canadian Smog Advisory Program. Can Respir J 1995;2(3): 155-160.

O n.J ECTIVE: To revit:w the evidrnce on health effects of air pollution for the Canadian Smog Advisory Program. METHODS : Evide nce w;1s reviewed by two expert pane ls. who were asked to define the health effects expected at levels o f exposure given by the National Ambient Air Quality Objecti ves. to examine a variety or issue., re lated to communicating with the public about environmental health risks. and to draft health messages for the advisory program. R ESU LTS: The panels concluded that health effects or ground-level 01011..: at k'vcls that occur in Canada include pulmonary inflammation. pu lmon;iry fu11c1 ion decrements. airway hypcrreactivity. rc.,piratory .,ymptoms, pos.,iblc inneas..:d medication u.,c and physician/cmngency room vi., -

its among indi viduals with heart or lung disease . rcducL'ci exercise capaL·ity , increased hospital admi ss ions and possible increased mortality. Similar effects we re felt to occur in association with airborne particlL·s. with the l'xccption of inflammatory changes, and with the addition or increaseJ schoo l absenteeism. Poor data 011 individual exposure were identified as a limitation of studi..:s on hospital admi.,.,ions and mortali ty. RECOMMENDATIONS: The panels identified the need to reflect the evidence accurately without unduly r;1i .,i11g public concern and r..:commended that advisory health messages identify expec ted health elkcts. while health care providers could more appropriately recommend protective actions to individuals. Supple mentary educational strat..:gies and evaluation of the advi .,ory program were also recommended. (Po11r I<' rc;_1-u,11 c. rnir 11ag<' [56)

Key Words: i\cfrisorics. ;\ir 1>01!111io11. ( !:one. S111og

CorrnJJ011dc11ff 111/d n·11ri111s: /),- /)m ·i,I M S1ieh. Air Q1w/11y I /ni/1/1 E/fi'ct., Nc.11 ·an"/1 Scctio11. Hcalrh Cu11ad11. 1111.,10/ lorn/or ()8()3 (', {111111('_1'

0

.I' Pasture. 01tmra. c)111urio KI i\ IIL2 _ lc!t·11//om' 6/ 3-957-3 132. Fax r,J .i-9-1 I -45-16. c-11wil duff .,ricf,_ut _11 c1112()2@isdrc1i3./1\\'C.cu '/'he rini-s e.,prcsscd i111/1is f'UJll-r arc rho.,c o(rhc 11wl1ors llllli dn 11nt necessarily rcprcscnr w1 o/jici11/ 11osiriu11 ,,(/lca/t/i Ca11w/11 C.111nt Pw1cl ji1r rlic Cauwlian S///og Adri.wrr Program. Chuir: L 0(/\·id Pcngclly Plin. Ocpar1111rnts of J\.frdici11,· 11 11d D1gi11ari11g

Phrsics. McMastcr Uni, ·cr.,itr. l'a11c/ 111l'lllil/'rs: /Jarid V Butes lWD FRCP FRCPC FA CP FR.SC. Ol'f>urt1111·11r o( //ca/t// Cure u11rl £1iidc111io/ogr. Unirl'l'sitr 0(/Jriris/1 c,,J,1111/,iu; Afork Fra1111i1011 MD. D1part111c11t., of Medicine u11d Lm·ir,111111c11t,il Ml'dici11c. l/11i\'!'r.1i1_1· of Roc/1csrer: Teresa M MtGrurl, MO. ( >111urio Mi11istn· o)Lahow: Andre1v D O.r111a11 MD MSc FRCl'C. De11ar1mc11r., of'Cli11irnl [11ide111io/ogr and Biostati.l'tic.l' and 1-'wnilr Mcdici11e. McMastcr U11i\'nsity : Mar/.: E Rai:c1111c /!Sc. /1.ir Quality /Im/ti, Ejfcct.l' R,·.1,·un/1 Section . Hcaltlr Cwwda: Lo11 S!in1/i·ld M,-\ PCng. Tl,c Mf:'P Co111pa11_r: Frances Sih·ernw11 fir!). 0 ,•11urtmc11t o(Medicinc. U11i1 'ffsit_r of Torn11tn: Peter W S11111111r.:r.1 !'Iii). ;\ir Qualirr Rc.1('(/rc/i /Jra11cli. Enrim111111·111 Ca11ada: S Murrin Tur/or P/1/). nc1ium11m1 of(; ,,ogm11l1_1'McM11stcr l/11ircr.,i1r: Sl'r'IT(' Vn lul MU MS,·. Oc/)(Jr//11e11t of'Medicinc. U11i1·crsit_1· o/'Britisli Co/1111i/1iu

Can Resp1r J Vol 2 No 3 Fall 1995 155

STIEB ET AL

Effets sur la sante de la pollution atmospherique au Canada : Resultats rapportes par un groupe d'experts pour le Programme canadien d'avertissement de smog

0BJECTIF : Passer en revue !es prcu ves des eflets sur la sante de la pollution atmospheriqm· puur le Programme canadien d\1verti,;sement de smog. METHODES : Les preuvcs ont etc examinees par dcux groupcs d'experts a qui !'on a demandc de dctennincr Ies cffcts attendus sur la santc [1 des nive;iux d'exposition fourni s par !es objectifs nationaux afferents f1 la qualite de ['air ambianr, d'cxamincr unc varietc de questions ayant trait al 'ini"ormation de la population sur !cs risques env ironncmentaux pour la sante, et d'cbaucher des messages sanitai res pour le Programme cl ' averti ssement. RESULTATS : Les groupes d ' experts ant conclu que lcs effets sur la sante de !'ozone au ras du sol 11 des niveaux detcctes au Canada comprennent notammcnt l'int1ammation pulmonaire, la deterioration de la fonction pulmonairc, l' hyperreactivite bronchiqlll·. de,, .,yrnptflmes respiratoircs . une augmentation possible

T HE TERM "SMOG" IIAS BEEN US ED IN NO RTH AMERICA

to describe a characteris tic form or air pollution that genera lly occurs from late spring to early fall. Smog was recognized as a Canadian pollution issue in the fede ral 'Green Plan' in 1990, and in 1993 Env ironment Canada introduced the Canadia n Smog Advisory Program. This report presents background infonnation on air pollution in Canada and summarizes the findings of an expe rt panel process undertaken in support of the Canadian Smog Advisory Program. It is a condensed and modified version of the original report on the panel process (I). Its purpose is to provide clinicians and public health workers with the information needed to respond appropri ately to questions or concerns of patients and members of the pub lic that may he triggered by snro.!! advisories .

BACKGROUND Although air 4uality in Canada has generally improved

over the past 15 years, smog episodes still Ol'cur. These episodes. which are primarily a summer phenomenon. consist principally of elevated concentrations of ground-level ozone. although al'icl aerosol s (a type of airborne particle) may also be present (2). A different form or smog, 'winter smog ' , may also lll'l'ur, whose principal constituents are sulphur dioxide and airborne particles (inl'luding acid aerosols) (2). G round-lewl owne and airbornL· particles were the focus of the panel process .

Ground- lcwl ('tropospheric') ozone. which should be d istinguished from stratosphcriL· o;:one ('the ozone layer' ). is a gas that is formed when its precursors, oxides of nitrogen and hydrocarbons. interact in the aunosphere in the presence of high temperatures and sun light (3 ). Smog and its precursors may be transported long distances through the atmosphere (3) with the result that high concentrations of ground-level owne may be found in both rural and urban areas (4). Although long range transport contributes significantly to ob-

156

de !'uti lisa tion des med icaments ct des consultations ti l ' urgence nu chcz le medecin parmi !cs individus soufl'rant d'une affect ion pulmonairc ou cardiaquc. unc tolerance rcduitc a r·cxcrcicc. unc augrnenlat ion des hospitalisations ct augmentation possible de la mortalitc . On pense quc des clTcts sirn ilaircs sc produisent en assoc iation avec !cs particulcs aerogcncs. f1 l'exl'cption des changemcnts inllammatoircs, ct en y ajoutanl une augmcntation de l'abscnrcismc scolaire. Des donnccs insuflisantcs sur !'exposition individue lle ant etc iclcnti fiecs comme unc limi ta tion des etudcs sur lcs hospitalisations et la morta litc. RF.COMMANOATIONS : Les experts ont idcntilil' le bcsoin de rclleter correctcmcnt lcs preuvcs sans trop sou lever d'inquietudes dans la population et ont recommandc quc !cs mcssagcs-sante iclentifient lcs e !Tcts attcndus sur la santc. pendant quc !cs pourvoyc urs des soins de santc pourraicnt plus adcqualcmcnt recommancler des comportemcnts protcctcurs aux indiviclus. Des strategies cducatives supplcmcnta ircs ct unc evaluation du Prog ramme d'avcrtisscmcnt ont aussi cte rccommandccs .

Po11r nhtcnir la rcr.1·ion.fi·an(·aise i1111igra!e cl<' <"<'I article. nm111111-

11i<111ec m •ec f" all/Cur {/ f" adreSSC i11tfi</II ('(' .

served ground-level ozone concentrations in a number or regions, its impacr is particularly apparent in Atlantic Canada. where peak concentrations may occur at night. In most other areas, peaks occur during the late afternoon and early evening in the summer months. In Canada, the current National Ambient Air Quality Object ive for ground-level ozone (I h maximum of 82 parts per bil lion ippbl - maxim um acceptable concen tration) is exceeded most often in southern Ontario. southern Quebec, Vancouver and southern New Brunsw ick (5) (Figure I) .

Airborne particles are very smal l pieces of solid or liquid matter, which vary in si ze, chemical composition and sou1n·. Smaller particles. which have the greatest health significance, tend to arise from man-made sources, particularly fuel combustion, and include acid aerosols such as sulphates and nitrates, as well as metal oxides (6). Larger particles consist mainly of naturally occurri ng substances. particularly soil (6). Particles less than IO ~1111 in diameter (PM 10) are considered 'inhalable' (7). The current National Ambient Air Quality Objective for total suspended particles (TSP - airborne particles of all sizes) is 120 µg/1113 for 24 h concentration. which is still exceeded at least I 0% of the time in some cities across Canada (5). The current US standa rd for PM 10 is 150 µg/rn 3 for 24 h concentration. Recent data reveal 24 h concentrations that exceed I 00 µg/m 3 in a number of Canadian cities (8). Health Canada is currently developing a Canadian PM 10 objective.

The Smog Advisory Program was introduced in the summer of l 993 under Canada 's Green Plan as a means of info1ming the public about both environmental and health aspects of smog episodes. The program was fi rst implemented in Saint John, New Brunswick, in southern Ontario and in the Greater Vancouver Regional District, and began in Montreal in 1994. As described earlier, these areas are situated in the geographic reg ions in which the highest groundlevel ozone concentrations have been observed. Under the

Can Respir J Vol 2 No 3 Fall 1995

I o EDMONTON

I I o CALGARY 2.3

WINDSOR 30.0 \J

Health effects of air pollution in Canada

DAYS

30

25

20

15

Figure I) Numhcr of days per year H'ith o:011e /cre/.1 in excess of the f hair quality ohicctirc of 82 pun.1 f>N /Jil/i,m. ,11 ·cmgc of 1/1/"l'c /1ig/ws1 rears ! ':)83- / 990 (Source : Cm'iro11111e11t Canada. 1994)

program, ground-level ozone forecasts arc produced cooperatively by Environment Canada, the provincial min istries of environment and munic ipal air quality offices. based on meteorological and air monitoring data. Advisories are issued when l h maximum level s are forecastcd to exceed a specified level, depending on the jurisdiction, but generally 82 ppb. They consist of an environmental message that describes the pollution sources that contribute to smog (chiefly automobi le transport) and the need for the public to reduce its depe ndency on cars, as well as a health message that advi ses the public of poss ible health risks associated with smog exposure. The exact content of the messages is determined by provincial environmental and health authoriti es. ln I 993 . the tirst summe r of the program's existence, four advisories were issued - two in Saint John and one each in southern Ontario and the Greater Vancouver Regional District. A similar number of adv isories was issued in 1994. As seen in Figure I. a sign ificantly greater number of episodes of elevated groundlevel ozone concentrations has occurred in these areas in previous years.

METHODS Health aspects of the advisory program were addressed for

Health Canada and Environment Canada hy two ex pert panels convened by the Institute of Environment and Health of McMaster University and the Un ive rsity of Toronto. The pane ls compri sed individuals with experience in air po llution health research . public hcalth, air pollution meteorology and


measurement, and hea lth care delivery. The chair and several pane l members had independe ntly conducted literature reviews before their participation in the panels and key references were provided to panel members in preparation for one-clay meetings of each group. Each panel was asked to define the health effects expected at levels of exposure given hy the National Ambient Air Quality Objectives; to examine a variety of issues related to communicating with the puhlic about env ironmental health ri sks: and to draft health me:ssages for the advisory program. Although under the Smog Advi sory Program. advisories are issued only for groundleve l ozone, e ffects of airborne particles were also L'Onsidered by the panels . While the same indiv idual chaircd bnth panels . great care was taken to allmv each group scope to produce differing conclusions and recommendations . Nonethe less. a strong concurrence was noted between the findi ngs of the two pane ls . Once the panels were completed, mi nutes of each pane l as well as a synthesis were circulated to the panel me mbers for comment and revision .

PANEL FINDINGS The pane ls considered a variety of evidence on the rela

ti onship between air pollution and health . This included lahoratory studies, which have examined the pathophysiolog ic:al mechanisms through which pollutants exert their effects: chamber stud ies. which have been used to measure various human heal th effects at contro lled exposure· levels: panel studies, in which (for example) children attending summer

157

STIEB ET AL

I I

'\

Mortality

Hospital admissions

Emergency room visits

Physician off ice visits

Reduced physical performance

Medication use

Symptoms

Impaired pulmonary function

Subclinica l ettects

\

\

Proportion of population affected

6 sc,e,;i, ~ of effect

Figure 2) Schrnulfic rc11J'('sc111a1io11 o{//1e /)/}f<'nlial heal!!, cffcc/s of air pol/111in11. 1\da1>tccl ll'ith 1>cm,issio11Ji·n1111!1c 1\111crica11 Thoracic S11cic1r (()J

camp have been followed with respect lo pulmonary function and ymptoms in relation to ambient pollutant levels: and studies based on administrative data on emergency room visits. hospital admissions and mortality and their relationship to changing pollutant levels. ll was noted that the latter ·ecologic' studies haw been criticized because they lack important data on individual exposure. and that in studies or exposure lo ambient pollution. il has been di ffic ult to sep:iratL'

TABLE 1 Expert panel summary of health effects of ground-level ozone

the effects or individual pollutants. particularly ground-kvel o;onc and acid aerosols.

The panels conceptual ized the potential health effects or air pollution as occurring in a logica l \:ascade' or ·pyramid ' . ranging from severe. uncommon events (cg. death) to mild. common effects (eg. eye. nose and throat irritation) and asymrtomatic changes of unclear clinical significance (cg. small pulmonary function decrements and pulmonary inflammation) (9.10). Thus. while according lo this 11H1dcl SL:vcre health events prec ipitated by air pollution would Ill' rare. there is a potentially large overall impact on he,lllh and well -being (Figure 2).

With respect lo ground-level 01,one. the panels kit that current palhophysiological evidence suggested that ozone is associated with an inflammatory response manifested by increased airway membrane permeability and bronchial hype1Teactivity ( 11.12). Some or the nxenl epidemiulogic:11 I ilerature reviewed by the panels indicated that pulmonary runction measures in children attend ing summer camp in southern Ontario were reduced on average by 3.5 to 7<1< wlll'Il I h av erage coneentrations of ground-level 01011L'. reached 140 ppb ( 13) . that approximately 5% of Ontario hospital admissions ror respiratory disease may be attributable lo elevated conccnlralion.s of ground-level O/\lllC (4.14) (up to \ 5';{ in those umicr two years of age I in combination with sulphate particles 1141). and that in Los Angeles the combination of ground-level ozone. nitrogen dioxide and lemperalltre accounted for 4% of the day lo day variability in mortality (excluding accidents and suicides) ( 15). Whether the effects observed in epidemiological studies can be directly allributccl to inflammatory responses seen in laboratory studies is unclear. The evidence for chronic effects is also unclear. The panels concluded that there was some evidence that certain groups arc more susceptible 10 the acute clTccts or groundlevel ornne. either on the basis of increased sensitivity (lhe

Ground-level ozone concentration (parts per billion - 1 h maximum)*

Population

General population (adults and children)

Good

No known harmful effects

50-80 80-1 50

Air quality descriptor

Fair

Respiratory symptoms with heavy outdoor exercise in sensitive people

Poor

Inflammation of respiratory tract Decrements in pulmonary function Airway hyperreactivity Larger proportion of population experiences symptoms with heavy outdoor exercise Reduced capacity for exercise/physical work

>1 50

Ve po_o_r __

Higher probability of effects described in 'poor' category

Respiratory illness in children with less intense exercise

Probability and severity of expected health effects increases with increasing exposure (time and level)

Individuals with No known Above plus possible Above plus higher probability of Higher probability of heart harmful effects increased: medication use; effects described in 'fair' category effects described in or lung disease physician/emergency room Possible mortality ·poor' category (including asthma) visits; and hospital

admissions

"50 ppb = Maximum desirable concentration: 80 (82) ppb = Maximum acceptable concentration: 150 ppb = Maximum tolerable concentration. Source reference 1

158 Can Respir J Vol 2 No 3 Fall 1995

very young, the elderly. those with chronic cardiac or resp iratory di sease) or increased exposure during outdoor activity (schoolchi ldren. joggers, cycl ists and other athletes, and outdoor workers such as fann and construction workers ). However. this was recogni zed as a controversia l area . The panels differed in their interpretat ion of the evide nce on the occurrence of hann ful effects in the general population at levels below 80 ppb.

/\ synthesis of the effects ide ntified by the pane ls at concentrations g iven by the Nat ional Ambient Air Quality Object ives is presen ted in Table I. This table summarizes the current sc ienti fic ev idence. weigh ing what the panels saw as the relati ve st rength of the evidence for various effects al various levels. The contents of the table do not translate the ev idence into appropriate messages for comm unicating with the gene ral public .

Although the pane ls were not spec ifically asked to address the issue or whether there was a threshold concentration for ground-leve l ozone below which effects wo uld not be expected, they were requi red to frame their findi ngs accord ing to the National Ambient Air Quali ty Objectives. which inevi tably rai sed the threshold issue. There was little support among panel members for the concept of a threshold concentration for effec ts of ground-level ozone, which is re fl ected by their concl usion that the probability and severi ty of expected health e ffects increases with increasing ex posure (Table I). However. it was recognized that this was a separate issue from choos ing an adm in istrative thresho ld concentration ( 16) for the purposes of issuing adv isories. The latter issue was fe lt to be more appropriately addressed by authorities in the individual regions where advisories are issued (as described earlier).

With respect to airborne particles. the panels felt that the pat hophysiolog ical mechanism through which they exert the ir effects on respiratory health was not wel l understood. Some of the recent epidemiological li terature reviewed by the pane ls (much of which ori gi nates in the Uni ted States ) indicated that e levat ions of PM to concentrat ions of approximately I 00 to 150 ~tg/mJ are associated with reductions in peak expiratory !low of up to 6% ( 17.18). approx imately si xfold increases in medication use :nnong asthmatics ( 18 ). 1.5- to twofo ld increases in resp iratory symptom reporting ( 17.18), 40% increa ·es in school absentee ism (19). statistically significant increases in respiratory hospital admissions (20) and up to 16% increases in mortality (excluding accidents and suicide) (21 ). The panels concluded that groups with greatest susceptibility appear to be those with chronic cardiac and resp iratory disease, although thi s was recognized as a controversial area. As was the case for ground-leve l ozone, although the panels were not specificall y asked to address the 4uest ion of the e xi stence or level of a threshold concentration for the effects of airborne p;.irtic les. the question again arose because the pane l was re4uired to fra me its findi ngs accord ing to various leve ls of exposure as was done for ground-leve l ozone. There was little support among panel members for the concept of a threshold for the effects or airborne particle~ .


Health effects of air pollution in Canada

"Ground-level ozone, the major component of smog. is of primary concern because it is a powerful irritant and can have potentially harmful effects on the respiratory system. Symptoms are most likely to occur in individuals who are physically active outdoors . People with heart or lung disease. especially asthma, may experience a worsening of thei r condition ."

··commonly reported symptoms include irritation of the nose and throat, cough , and chest tightness . Minimize your exposure by avoiding outdoor exercise particularly in the afternoon and early evening when ground-level ozone concentrations tend to be at their highest."

"Children tend to be more sensitive tt1an adults because they breathe faster and in the summer spend more time outdoors being physically active. Reduce your child's exposure by encouraging outdoor activities early in the day when pollutant levels are lower."

Figure 3) Sa111r1le of public infomwri,111 111essagcs //lade arnilahlc hy Health Cllnlldu to s11p1,le111e111 Slllog i\drisory Prograill /1/Cssllgcs. S011ffc refere11cc 22

PANEL RECOMMENDATIONS While the panels made a number of wide-ranging recom

me ndations, only those relating to the content of health messages and their implementation are summarized here.

W ith respect to the content o f health messages, pa,1icular issues identified by the pane ls included the followi ng: appro priate emphasis fo r ' diagnostic' versus ' prescriptive ' messages (those that ident ify expected health e ffects versus those that recommend protective actions): identification of target groups: ensu ring that messages accurate ly re flect the scienti fic evidence and do not unduly raise public concern: and selection of an appropriate threshold for the ground-level ozone advisory. In consultation with provinc ial public health authorities. it was strongly recommended that the health messages be diagnostic only, wi th the recommendation that more spec ific prescriptiw adv ice be obtai ned from local public health authorities and/or personal health care providers fam iliar with the individua l' s clinical history.

W ith respect to implen11:·ntation aspects of the advisory program. the panels recommended supplementary education strategies di rected towards indiv iduals at risk as we ll as parents , teachers. athletes, coaches, health professionals and public health officials, and identified the need for evaluation of the impact of the advisory program.

In response to these recommendations Health Canada has deve loped a series of supplementary public informat ion messages, which have been made available to the public in both official languages through the media. physicians ' offices, hospi tals and parenting magazines (sec Figure 3 for sample messages ). In addition, Health Canada is col laborat ing with Environment Canada in conducting public surveys to evaluate variou · aspects of the adv isory program. includ ing awareness of advisories and advisory-related changes in behaviour.

159

STIEB ET AL

CONCLUSIONS The expert pane l process se rved as a rapid means of

identi fying and interpreti ng the e vidence on health e ffects or ground-le ve l ozone and a irborne partic les . Mounting evidence was identified linking e le vated concentrat ions of these pollutants with a spectrum of harmful effects on health, and recomme ndations were made regarding e ffectiv e communication with the public about these risks. Note: The original report of the pane ls (refe rence I). including a de tailed reference list, as we ll as public information materia ls on various air pollutants, arc available t'rom the correspond ing author.

REFERENCES I. Pengelly LO, Taylor SM . Stieb D. CanaJian Smog Advisory

Health Matrices for Ozone and Suspended Particles, Final Report . I lamilton anJ Toronto: Institute of Environment and Health. prepared for Hc:dth and Welfare Canada Environmen tal Health Directorate, 1993 .

1 Wor!J Health Organization , Reg ional Office for Europe : acu te· effects on health of smog episodes . Report on a W HO meeting: I 990 Oct JO-Nov 2, 's Hertogenbosch , Nethc rla11ds. Copenhagen: WHO Regional Publica tions. European Series . No 43 . 1992 .

. l. Li ppman M . Health e ffects or 01one - a critical rev iew. J Air Poll Control Assoc 1989:19 :672-95 .

+. Burnett RT . Dales R. Raizcnnc ME. ct al. Effects of low ambient level, of ozone and sulfates on the frequency or respirato ry admissions to Ontario ho:;pital:;. Env iron Rc·s 1994:65: 172-94.

~ Hilborn J, S till M. Canadian Perspectives on Air Pollution. Ottawa: Minis ter o r S upply and Services Canada. 1990.

6. Spengler J D. Outdoor and indoor air pollution. In: Tarchcr A B. ed . Principles and Practice of Environmental Med ic ine. New York: Plenum Medical Book Company , 1992 :2 1-4 1.

7. Review or the national air quality standards for partirnlatc'. matte r: assessment o r sc ien tific and technical information. Rcp,11·1 No EPA-450/5-82 --00 I. Re:;earch Triangle Park: Strateg ics and Air StandarJs Division. ()!lice or Air Quality Planning and Standards, US Env ironmental Protection Agency. 1982.

X. Dann T. PM 10 and PM2_ 5 Concentrations at Canadian Urban Sites: 1984- 1993. Ottawa: Environment Canada. 1994.

160

'>. American Thoracic Society. G uidel ines as to what constitull's an adverse respi ra tory health cflecl. with special re ference to epidemiolog ic stud ies o r air pollution. Am Rev Rcspir Di s 1985: 13 1 :666-8.

I 0. Bates DY. Health indices o f the adverse e ffects or air pollution. The ques tion or coherence. Environ Res 1992:59 :336-49.

I I. C rapo J. Miller FJ. Mossman B, Prior WA , Kiley JP. Relationship between acute inllammatory responses to air pollu1a11t s and chronic lung disease. Am Rev Rcspi1· Dis 1992; 145: 1506- 12.

12. Devl in RB . McDonnell W F. Ma nn R. ct al. F.xposurc or humans to ambient levels o f 01,onc for 6.6 hours causes ce llula1 and biochem ical changes in the lung. Am J Rc·sp ir Cell Mo! Biol 199 1 :4: 72-8 1.

IJ. Rai 1,ennc M E. Burnett RT, S te rn B. Franklin CA, Speng ler JD. Acute lung fun cti on response:; to ambient ac id aeroso l exposures in childn:n. Env iron H(·alth Perspect 1989;79: 179-85.

I+. Ball's DY. S iz to R. Air pollution and hospital admissions in Southern O ntario: the ac id summer haze c!Tecl. Environ Res I 987:43 :3 17-3 1.

15. Kinney PL. 0 1,kaynak H. Associations o f daily mortality and air po ll ution in Los Angele:; ou nty. Environ Res 199 1 ;54:99 - 120.

I (1. Penge lly LD. S ilverman FS. Taylor S M. A Hiera rchy o r Potential Health Effec ts From Air Pollution Exposure. Final Report. Hamilton and T rnonto: Institute of Environment and Health. 1994 .

I 7. l'upe CA, Dockery D\V. Arn tc health eflel'ls or PM 10 pollution on symptomatic and asy mptomatic ch ildren. Am Rev Rcsp ir Di s 1992: 145: 11 23 -8.

I~. Pope C A. Dockery OW, Speng ler JD. Rai,.cnnc ME. Respiratory health and PM 10 poll ution. A Jaily time se ries analysis. Am Rev Rcspir Di s 199 I:! 44:668-74.

I'>. Ransom MR. Pope CA. E lementary school abse nces and Prvl Iii pollution in Utah Valley. Envi ron Res 1992:58: 204- 19 .

20. Pope CA. Respi ra to ry hospital adm i~s ions assoc iat ed with PM 1n pollution in Utah , Sa lt Lake. and Cache Valleys. Arch Environ Health 1991;46:C0 ,7.

21. Pope C A. Schwartz J. Ransom MR . Dai ly mortality and PM Iii pollution in Utah Valley. Arch Env iron Health 1992 ;47:2 11 -7.

11 Environment Canada, Health and Welfa re Canada. Ene rgy. Mines and Resources Canada, \ madian Counc il of Ministers of the Environment NOx/VOC Office .. Air Care: A parents Guide to A ir Quality and Health. Today 's Parent G roup, 1993 .


Submit your manuscripts athttp://www.hindawi.com

Stem CellsInternational

Hindawi Publishing Corporationhttp://www.hindawi.com Volume 2014


MEDIATORSINFLAMMATION

of


Behavioural Neurology

EndocrinologyInternational Journal of



Disease Markers


BioMed Research International

OncologyJournal of



Oxidative Medicine and Cellular Longevity


PPAR Research

The Scientific World JournalHindawi Publishing Corporation http://www.hindawi.com Volume 2014

Immunology ResearchHindawi Publishing Corporationhttp://www.hindawi.com Volume 2014

Journal of

ObesityJournal of



Computational and Mathematical Methods in Medicine

OphthalmologyJournal of


Diabetes ResearchJournal of



Research and TreatmentAIDS


Gastroenterology Research and Practice


Parkinson’s Disease

Evidence-Based Complementary and Alternative Medicine

Volume 2014Hindawi Publishing Corporationhttp://www.hindawi.com

health effects of air pollution in canada: expert panel

Documents