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 RAIZEN NE* 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 Res pir J 1995;2(3): 155-1 60. 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 ex posure given by the National Ambient Air Quality O bjecti 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 panel s concluded that health effects or gro und-level 01011..: at k'vcls that occur in Canada include pulmonary inflammation. pu lmon;iry fu11c1 ion decrements. airway hypcrreactivity. rc.,piratory .,y mptoms, 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 mo rtali ty. RECOMMENDATIONS : The panels identified the need to reflect the evide nce accurately without unduly r;1i .,i11g public concern and r..:comme nded that advisory health message s 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 I01!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 (', 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 _11c1112()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. Chu ir: L 0(/\·id Pcngclly Plin. Ocpar1111rnts of J\.frdici11,· 1111d D1gi11ari11g Phrsics. McMastcr Uni, ·cr.,itr. l'a11c/ 111l'lllil/'rs: /Jarid V Butes lWD FRCP FRCPC FA C P 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. McMastc r 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·c rsit_1· o/'Britisli Co/1111i/1iu 0
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Can Resp1r J Vol 2 No 3 Fall 1995
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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 sa nte 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 question s aya nt 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 fon ction pulmonairc, l' hyperreac tivite bro nchiqlll·. de,, .,yrnptflmes respiratoircs . une augmentation possible
T
HE TE RM "SMOG" IIAS BEEN US ED IN NO RT H AME RICA
to describe a characte ristic form or air pollution that genera lly occurs from late spring to early fall. Smog was recog nized 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. T his report presents background infonnation on air pollution in Canada and summarizes the findings of an e xpe rt panel process underta ken 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 app ropri ately to question s 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. con sist principally of elevated concentrations of gro und-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 nitroge n 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 ob156
de !'uti lisa ti on des med icame nt s ct des consultations ti l' urgence nu chcz le medecin pa rmi !cs individus so ufl'rant d'une affect ion pulmonairc ou cardiaquc. unc tolera nce rcduitc a r·cxcrcicc. unc augrnenlat ion des hospitalisations ct aug mentation possible de la mortalitc . On pense quc des clTcts sirn ilaircs sc produisent en assoc iation avec !cs pa rticulcs aerogcncs. f1 l'exl'cption des changemcnts inllammatoircs, ct en y ajoutanl une au gmcn tation de l'abscnrcismc scolaire. Des donnccs insuflisantcs sur !'exposition individue lle ant etc iclcnti fiecs comme unc limi ta tion des etudcs sur lcs hosp italisations et la morta litc. RF.COMMANOATIONS : Les experts ont id cntilil' le bcsoin de rclleter correctcmcnt lcs preuvcs sans trop sou lever d'inquietudes dan s la population et ont recommandc quc !cs mcssagcs-sante iclentifient lcs e !Tcts attcndus sur la sant c. pendant quc !cs po urvoy c urs de s soins de santc pourraicnt plus adcqualcmcnt reco mmancl er des comportemcnts protcctcurs aux indiviclus. Des strategies cducatives supplcmc nta ircs ct unc evaluation du Prog ramme d'avc rtisscmcnt ont aussi cte rccommandccs .
Po11r nhtcnir la rcr.1·ion.fi·an(·aise i1111igra!e clN /Jil/i,m. ,11·cmgc of 1/1/"l'c /1ig/ws1 rears ! ':)83- / 990 (Source : Cm'iro11111e11t Canada. 1994)
program , gro und-level ozone forecasts arc produced cooperativ ely by Environment Canada, the provincial min istries of environ ment and munic ipal air quality offices. based on meteorological and air monitoring data. Advi sories are issued when l h maximum level s are foreca stcd to exceed a specified level, de pend ing on the jurisdiction, but generally 82 ppb. They consist of an environmental message that describes the pollution sources that contribute to smog (chiefl y automobi le transport) and the need for the public to red uce its de pe ndency on cars, as well as a health message that advi ses the public of poss ible health risks associated with smog exposure. T he exact content of the messages is determined by provincial environmental and health authoriti es. ln I993 . the tirst summe r of the prog ram's exi stence, four ad visories were issued - two in Saint John and one each in southern O ntario and the Greater Vancouver Regional Di strict. A si milar number of adv isories was issued in 1994. As seen in Figure I. a sign ifi cantly greater number of episodes of elevated gro undlevel ozone concentrations has occurred in these areas in previous years.
measurement, and hea lth care delivery. The chair and several pane l members had independe ntly conducted literature reviews before their participation in the panel s and ke y references were provided to panel members in preparation for one-clay meetings of each gro up. Each panel was asked to defi ne the health effects expected at level s of exposure given hy the National Am bient Air Q uality Objectives; to examine a variety of issues related to communicating with the puhlic abo ut env ironme ntal 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 mbe rs for comment and revision .
METHODS
The pane ls considered a variety of evidence on the relati onship between air pollution and health . This included lahorato ry studies, which have examined the pathophysiolog ic:al mechani sms through which pollutants exert their effects: chamber stud ies. which ha ve been used to measure various hu man heal th effects at contro lled exposure· levels: panel studies, in which (for example) children attending summer
PANEL FINDINGS 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 Toron to. T he pane ls compri sed individuals with experience in air po llution health research . public hcalth, air pollution meteorology and Can Respir J Vol 2 No 3 Fall 1995
157
STIEB ET AL
'\
Mortality Hospital admissions Emergency room visits
\
\ 6 sc,e,;i,
Physician off ice visits
~
of effect
Reduced physical performance Medication use Symptoms Impaired pulmonary function Subclinica l ettects
I
I
Proportion of population affected
Figure 2) Schrnulfic rc11J'('sc111a1io11 o{//1e /)/}fcm,issio11Ji·n1111!1c 1\111crica11 Thoracic S11cic1r (()J
camp have been followed with respect lo pulmonary function and ymptom s in relation to ambient pollutant level s: and studies based on administrative data on emergency room visits. hospital admissions and mortality and their relationship to cha nging pollutant level s. 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'
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 decreme nts 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 -be ing (Figure 2). Wit h respect lo ground-level 01,one. the panels kit that cu rre nt palhophysiological evidence suggested that ozone is associated with an inflammatory response manife sted by increased airway membrane pe rmeability and bronchial hype1Teactivity ( 11.12). Some or the nxenl epidemiulogic:11 Iilerature 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. 20.
21. 11
an adve rse res pi ra tory he alth cflecl. with special re ference to epidemiol og ic stud ies o r air pollution. Am Rev Rcs pir Di s 1985: 13 1:666-8. Bates DY. Hea lth indices o f the adverse e ffects or air pollution. The ques tion or coherence. Enviro n Res 1992 :59 :336-49. C rapo J. Miller FJ. Mossman B, Prior WA , Kiley JP. Relationshi p bet ween acute inllammato ry responses to air pollu1a11t s and chro n ic lung disea se. Am Rev Rcspi1· Dis 1992; 145: 1506- 12. Devl in RB . McDonnell W F. Ma nn R. ct al. F. xposurc or human s to ambi en t levels o f 01,o nc for 6.6 hours causes ce llula1 and bioche m ical chan ges in the lun g. Am J Rc·sp ir Cell Mo! Biol 199 1:4:72-8 1. Rai 1,ennc M E. Burnett RT, S te rn B. Franklin CA, Spe ng le r JD. Acute lung fun cti on res ponse:; to ambient ac id aeroso l ex po sures in childn:n. Env iron H(·alth Perspect 1989;79: 17 9-85. Ball's DY. S iz to R. Air pollution and hosp ital admission s in Southe rn O nt ario: the ac id su m mer haze c!Tecl. Environ Res I 9 87 :43 :3 17-3 1. Kinney PL. 0 1,kaynak H. Associati ons o f da ily mortality and air po ll ution in Los An ge le:; ou nty. Environ Res 199 1;54 :99 - 120. Pe nge lly LD. S ilverman FS . Taylor S M. A Hiera rc hy o r Poten tial Health Effec ts From Air Po lluti on Expos ure. Final Report. Hamilton and T rnonto: Institute of Enviro nment and Hea lth. 1994 . l'upe CA , Dockery D\V. Arn tc health eflel'ls or PM 10 pollution on symp to ma tic and asy mptoma tic ch ildren. Am Rev Rcsp ir Di s 1992: 145: 11 23 -8 . Pope C A . Dockery OW, S peng le r JD. Rai,.cnnc ME . Res piratory health and PM 10 poll uti o n. A Jaily time se ri es analysis. Am Re v Rcspir Di s 199 I:! 44:668 -74. Ransom MR. Pope C A. E lemen tary sc hool abse nces and Prvl Iii pollution in Uta h Valley. Envi ron Res 1992:58: 204- 19 . Pope CA . Respi ra to ry hos pital adm i~s ions as soc iat ed with PM 1n pollution in Utah , Sa lt Lak e. and C ache Valle ys. Arch Enviro n Hea lth 1991;46 :C0 ,7. Pope C A. Schwartz J. Ransom MR . Dai ly mortality and PM Iii pollution in Utah Vall e y. Arc h Env iron He alth 1992 ;47:2 11 -7. Environ me nt Canada , Hea lth and Welfa re Canada. Ene rgy. M ines and Resources C anada, \ madian Counc il of M inisters of the Environmen t NOx/VOC Office.. Air Care: A parents Guide to A ir Quality and Hea lth. Today 's Parent G ro up, 1993 .
Can Respir J Vol 2 No 3 Fall 1995
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