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Philip Morris

Indoor Air Pollution in Developing Countries

Date: 19900000/P
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Chen, B.H.
Hong, C.J.
Pandey, M.R.
Smith, K.R.
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E41
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Shanghai Symposium on Environmental Heal
2nd Natl Conference on Environmental Hea
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Shanghai Medical Univ
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Chang, K.M.
Chen, B.H.
Hong, C.J.
Lin, H.S.
Wang, J.
Wong, C.J.
Yang, X.
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2501154504/2501155174/Ets and Lung Cancer in Nonsmokers Volume II
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Bir Hospital Kathmansu
Environment + Policy Inst
Shanghai Medical Univ
Un Environment Programme
Who, World Health Org
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2501154505/5173

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MARG, MARGINALIA
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INDOOR AIR POLLUTION IN DEVELOPING COUNTRIES 9 . H. Chen.• C. J. Ftong! M. R PandeY & K. R. Smith` A r pollution in general and indoor air pollution in particular have txen associated in many people's mind with mdustnalitat+on and urbam2atton and, thuS. with the cities of developed countries where most of the measurements have been made. Rt- cently. however, the UtvEPNVHO Global Environment Monitoring System IGEMSY has demonstrated quite convincingly that the worst ambient Conditions re- ported today obtam in the cit3es of developing coun- tries, In a similar fashion, although most studies of indoor air quality have been carried out in devel- oped-country bwldings. for many important pol- lutants the largest +ndoor.pol3utant concentrations and exposures are also found in the developing countnes in both rural and urban households. Worldwide, there are four principal classes of indoor pollutants 111, those dertved from: (r) combust on e g- carbon monoxide. particulates, and sulfur and nitrogen oxides from cooktng 6SOves. faace neaters and cigarettes (environ• mental tobaL'.o smoke-ETS); r„t buitd ng materials, furnishings and themrcal pxoductss e.g pest+ctdes, volatile organic trom- pountls, formaldehyde: (ut) the ground vnder the bwidrng. i.e. radon: trvl biotog cal processes. e.g, mold- mildew, mites. As with ambient em ssions. the impact of indoor emissions on Concentrat3ons depends directly on vG7ttiatuon tairliow and mixing volumel. In generaf, most housing in developed countrne5 lies tn tem- pera*e IaLtudes ano thuS has relatively low air ex- chant)e rates.s i e tvp4cally one air change per hour or less. Under these condittons, even rather small emission rates can result tn indoor concentrations that exceed those outdoors, considering also that indoor air qualtty is affected by outdoor levels. Since people spend a great proport on of time indoors. typ+Ca3ly 90% or more, +ndoor pollution is lrequently the predominant factor in total exposure. In the developing world. however, much housing lies in tropical and Subtropical regions and typically has much higher ventilation rates. In these ctrcum- ftances, it takes fa rly high emission rates to pro- duct significant pollutant fevets. Unfortunately, there seem to W many situations in which suoh strong mdoor sources exist. f>noreover, in spite of be ng a mtnortty, several hundred million people in develop• tnq countrtes reqwre space healing for a significant part of the year, and thus share with developed • antanat.onal sroqrarnete en Lr»n+cN saMev. worfe rMam+ Orqan+rat.on. GeMwq • School of t•not•e N.aet+. Snsr,gns. r~Aed" i/n+vwsay. Snanqna.. Lama ~ 6,r Nofpnl/ Kltnnynay. NeO4t •EmHOr•tnem ano Pohcr rmtAUte. East^west Canter, MonolulY. M..w0,1, und.d States ot A+n..xa • Gtowt f n no• ~ ent Monno-q Syar.m assa»m.nr of v.aart aN awwy un-:ee Matroms EAnronment Praqren,n,.AVanE tbaith jorqJNtatson. lqsa IunokwyM0 OOCurMntl countries the d Ntcult trade-off between space- heattng fuel efficiency, ventilation and indoor air quality. This review focuses on indoor combustton•denved pollutants, principally because comparatively little work has been publ shed on the Other three Cat• egortes in developing sountnes. Although the ma n purpose is to review the available ep3demtotogical studies, the relevant sources and pollutants will be briefly discussed frrst Indoorsouross Due to the generally higher ventilation rates. ETS has riot been singled out in developingtountry studies to date. Wstn the siarmtng increase in smok• ing rates and the chang ng housing stock in some developing CDuntr es, however, suCh research may well be warranted Although such minor Combustion sources as incense and mosouito cotis have otca• s onally been exam,ned, most efforts have ton- Centrateo on cooking and heating stoves. After tobacco, the most common indoor pollution source ot concern in develooed-country ttudies nas been gas cookstoves In the g obal context. however, gas stoves are near the upper end of an evolution in the pualtty of household fuels. sometimes called the energy ladder (2). Although dependent on local con- ditions. at the lowest rung might he those house- holds that rely on tlried an~mal dung and scavenged tw gs and grass for cooking The next step might be crop residues followed by wood, and then Charcoal. The first non•biomass fuel might be kerosene, as in Indta, or coal, as in China Highest on the ladder lie bottted and piped gases and. for some rich com• muntties. eiectractty, In general, each step involves an increase in the Cooking system's levels of technology, cleani,ness. eff{ae,~cy and cost. O,n- a--glob_al scale, it is esttm~ted that more tt~an half Ot tnt worid't h0usehDlqCDOk d~t~ wtth u~- processed solid fuels._i.e,•biofuels or coal. An un• 1cnOwn- Dut tign~litlnt,._.ps_Opottton of thas activity akes Dlace in condtupns where mu~Q~h~~• ~ornt___e_f_iluent is ;eleese_d +nto the living srei. A~lthougrl ventdation rates are_oha~ rtlatively hi9h, t~s emttsion f~ctcrt ior such fuelsara _so 9reat that indoor concentrittons antl eapos_ur~s t~n be qutt: siqnificant. Comoared with ga+;tovts, foi t:a~ie, av_e sioves usin one of the cleaner biotuels. wood. tYpiclly telease 50 t+mes more pol utton tn coo rng ~ii.~~ vva n m AfLp.u~n lest_ DrlyiSnL~pac! *uting wtth un- p_rocesseCsolid tue_Is csn a-IS~1tad to htoh indoor ai~ollution levels. For part of the year in the htgh- a~tttu~@~1lei ~v3foQtng Countnt; inlli major _, reqions tAs~a. Afrita, lstm Amenca and Oceeniaf, unrerted sntt:_t~at,n~ wqth bomiss_fucls iscon+mon. In addition, in much of temperate China, •V7I ~ Jp+qr F,WS 48 1111901 2501154754
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significant indoor Concentrations result because of the high emission rates of coal fuels in s+mple stoves. although the pollution is itss serlous with venting, as is the csse in most Chinese Cutles. 72E - JEpidtn+ioloyy Adhough. by internatuonal comparlson. the *x- posures received in households in many developing eountroes are large. epidemiological studies are stdf difficult. Expected short•term lacutel efiects. such as acute respiratory infections tARlt, have many Other important risk factors. some Of which Correlate with pollution exposures. Long•latency tffects, Such as cancer and chronic obstructrve lung olsease ICOLDI. also involve other risk factors I4loreover. it is tl/f• ficult to associate these effects with previous ex• posures because Of the Iong Intervsl between these exposures and the onset of rllness tthe appearance of symptomsl (5). Physiological and biochemical markets. such as lung function and immunological status. are only indicators of the particular path- ology. for the sake of conciseness this review focuses on developing•country studles published since 1980 and which intlude a health•relat+d endpoint. Most of the early studies are nted. but not discussed in detail. and purely environmental studles are only men- tioned occaslonally. i.e. those that looked only at exposures' The studies have been divided according to general category of source. biomass or coal, and the health-related tndpornt being examined. Most have been done either in South Asia with rural populatoons using biomass. or in China with urban groups using coal. It is impossible at this po/nt to tlenve a reliable estimate of the total developing-country population exposed to what m+ght be termed -excesslve" in- door concentratlons, partly because there are few internstlonallv•reco9nmted standards for household concentrations. Assuming that they would be at least as stringent as outdoor standards, the total number of people exposed clearly rivals or exceeds that exposed to excessive ambient concentrations in all the world's ntles.' i.e. several hundred million. Given the greater time spent indoors and the known magnitude of concentrations in many situations however, the total global dose-eDurvalent Umount actually inhaledl is probably hlgher for some impor- tant pollutants. e.g. partlculates 137. Pinpointing the actual sources of exposure rf further compllcsted in many urban and even same rural ereu, because indoor concentrations are influenced by outside as well as inside sources. Pollutants In spne of the long history of fasunat on with fire and hundreds of years Of sclentllic ettort. the ability to predlct the detailed behaviour of combustion in any but the simplest configurations of fuel and air has eluded us. tUevertheless. empirical evidence has shown that unprocessed solld fuels produce hun- dreds of chemical compounds because of the incom- plete combustlon that occurs under the operating conditions of simple cooksloves. which are Ohen little more than three-rOcks Of a small open-ended box Of Clay, $oth coal and blomass act this way, although the mix of compounds from each is signlfi- cantly dlfferent. Unlike cos/, biomass generally con• tarns few intrinsic Contaminants. such as sulfur, trace metals and ash. and thus can, under proper oon- dltlons, be burned with no releases other than the products of complete combustlon. i.e. carbon dioxide and water. kJntortunately, it has turned out to be difficult to reliably create these eondrttons in modestly-priced household dewces. As with tobacco smoke, which is also the result of open biomass combustion, :uch cbokstove smoktjs. ~ comollcated matyrl. 0f aeio;gl_tdrqpie_tf__tln~t__lQhd partic~s/ and pases. §iomass ul+ok+ eo_ntins_31Q- t~ifi~nt amounts o~v~al D{ tht imDOriAt ool• lutaIIts. for whleh most countrles heve set stsndsrdr. arbon manoxide aniculates. h dr_txsrbons and, to a i+sser extent, nitrogen ozld+s. Perhspf more im- portsnt however is that the a+rpsol contains many organic compounds that are thought to be toxic. carcinogenic. mutagenlc or otherwise worrisome Isf. Coal smoke conta/ns all this plus additional poi- iutants. e.g. sulfur ox,des, inorganic ash particles and heavy metals such es lead. it is difficuh to make generalizations about the relative amounts of each kind of pollutant however, because emissions can change with relatively small changes in fuel quality, configuration and combustion, and Compsratively little detaded research has focused on such con- ditions. 'i.r a revrw M e5twsun nueys rNn.9 rs s0Tw.. tr" felplMce /iL ter tneN euTMMne GW/. Mf WeNenr't• 1e1. Biornass-SourA Asia. Africa. Guatemala and Papua New Guines The vest maJority of rural inhabitants in these parts of the world use unprocessed biomass fuels. Although significant in some communltt+s, the utili- tation of these fuels in Cities has been dropping as households move up the energy ladder, i.e. to ker- osene and bottled gss. Proport+onately, household coal use is minor, but it involves tens of millions Of people and seems to be on the increase as tht availability of biomass fuels dwindles and petroleum fuels remain relatively expensive. Carboxyhsemo9rob+n 1hrbCD/. In a study of osrbon monoxide IC01 concentrations in 130 biomass- burning kitchens of two Guatemalan villages at dif- ferent elevations II50 m and 1350 m1. Dsry tt at.171 also determined HDCO blood concentrations in women. They found lower NbCO levels in women cooking in well-ventilated kftchens. but no tllfferente in concentratUons between houses having similar ventrtatlon but situated at different attnudes. In both well-ventilated and poorly-vent+lated ktt- chens. how+ver, there were higher HDCO levels in the hlghenalt/tude village. with blood reaching 34% iibCO in some wom+n as s result Of conclntrst,ons of 30-SO ppm during the cootang period. In other words, at the Same CO Concentration, exposures at higher elevations produced higher NbCO levels, a finding consistent with known physiological mach- anisms and • significant consideration in those many high.attltude areas of the developing world where solid fuels are burned for space heattng wrthout ventilation. Lung function. To test for the effea of domestic smok+. Pandey et al. (d) used a dry poRable eplro• meter to measure lung function in a random sample of 150 women aged 30-44 years living in a rural area on the Outskirts of 1Cathmandu valley at an elevation a" iKa< sow w,Mr r I"" 2501154755
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- 129 - pf 1600 m, The area rs tota+ly free from industrial and atmospher3c pollutlon antl women spend con- siderable time near the hearth, which is used for both cooking and heating Smoke concentrations ere high because dwellings are ill-ventilated and without ch+mneys. The selected sample comprised 6 groups of 25 subjects in each of 3 se3f-reportetl durations of daily smoke exposure for both srnokers and non- smokers. All the spirometric tests IFVC, FEVI and FMEF 25-751 were pertormed in the standard way recommended by the American Thoracic Socltty, Variat ons in age. height, arm-span and weight be- tween [t1e three levels of exposure to domestic smoke in Doth the smokers and non-smokers were compared but no Srgn+ficent differences were found. There was a fall of mean FVC, FEVI and FMEF 25-75, however, as duration of exposure +ncreased. This decline was found to be statistically significant among the sr+tokers but not among the non- smokers, Similar results were found after adjusting for age and height. Respirarory symaroms tn Ahmedabad, western India, studies of the incidence or cough, cough with expectoration, dyspnoea and lung abnormalities round a statistically significant IP < 0.051 higher inci- dence among women cooking with smoky fuels r9•1i1 The rnvestigators also noted complaints by the women about the irritating effect of the smoke, D:rtrru V*lv on the eyes in a three-year prospective study of clinical morbid. rty ind air pollution in three areas ot Bombay city and in one rural area nearby Karnat et al. 1721 found that the rural sublects were smaller in s te. had lower lung function for their body stature and a n,gher rnc dencp of cough ana dysDnoei Many of the resp-ratory syT*rptorns eih,b+ted by the rural Dopu1Y,1+9'n were s milar tD those of the moderately o* severely polluted urban areas rather than the non-oolluted areas. Use of wood for kitchen fuel is one of the explanations given by the authors for this fndng, In a study conducted in tadakh, lKe,th 6311, personal commurncationl a high prevalence of chronic respir- atory symptoms was noted, particularly among women, which rrses steeply with age to affect the malOrity of Dltler people, About One-OuaRer of men and one-third of women over 50 have lung functipns s:,qqrst>>re of obstrutrve avwavs disease, and this becomes worse in .nnttr. Tobacco smoking itas so far developed only in about 20% of the men but is virtually unseen in women. It has been suggested that domestic pollution, which is significant through- out much of the year in this high-altitude area, appears to play a part in creating this pattern. Chronic obstructive lung disease in a survey carried out in a housing complex in Chand garh {Ind3al and in a nearby v llage, a study was made of the records of 2 180 women aged over 20, working with d fferent domestic fuels (73). Ssxty-six women 13'ti1 had symp- toms of chronic brOnchitrs, the highest number be ng in those who used the chulla Itraditional un- vented cookstovel for co0ktng, The cooking fuels were categorized in the following groupsI-liquefied Petroleum gas ILP(3); 8-kerosene; 1ll-toal: and IV-chuJt4 (wood and cow dungl. Five per cent of the sub)ects in group IV had ohronic bronchitis compar- ed to 1.5% and 1.3% in groups I and II, respectively. This difference was statisUcally s/gnificant IP < 0.011. Analysis of peak expiratory flow rate showed it to be low in subjects in group tV, but after adjusting for age end height, no d Nerence was found between the four groups. Hospital statistics in Ntpat showed an unusually high propoR+on 14{y.S of cor pulmonale in hospital card sc admrss ons 1141, indicating the need for field studies to determine the d str but on and magnitude of chronic bronch t s and chron c cor putmona7e, and to identify the factors respons ble f15/ Four sites wert selected for this purpose' urban Kathmandu. nearby vallages from Kathmandu Valley in the h lls reg on, a village district in the plains region iterail near India, and a d str,ct in the mounta ns. A survey of the prevalence of chronic bronchitis in the area of the hill villages was used to determine the reflulred sample size in other areas. In the plains village, a simple random sampl+ng method was used to select the sample. Two-stage random sampling was done in the urban areas and in the mountatn district. In all the study areas. houses wert rll-vent,lated and without ch3mneys. fvtast of the houses had only two or three rooms, but many had two floors. Cooking was done on traditional stoves in a corner of one of the grountl•floor rooms in the morning and evening rthe villagers take only two main meals a oay1. Most houses in the hills and mountains were customanly heated by means of an open fire in a fireplace known as an agerto dug into the floor of a ground- floor room. Members of the fam iy sit around the ageno in the morning and evening to keep them- selves warm. The ageno is also used for prepanng canle fodder in the mornmg and snacks for family members Except in urban Kathmandu, tnere was no general industrial air pollution. A Cuestronnarre, mod{fied sl,ghtly for different s+tes, recorded demographic rnformat on and exposure- related information such as smok ng hab+ts, location of kitchen, type of fuel used for cooking and heat3ng and average t me spent daily near the fireplace. along w th the information required to diagnose chronac bronchitis according to the British Medical Research Council criteria. Emphysema end Cnronic cor pulmonate were d~agnosed accord ng to the WHO Expert Committee criteria. The tndivrduals were classified as srnokers. past smokers. or non- Smokers and inio various strata according to self- reported number of hours spent da ly near tht stove wher'e- presumabiy, the highest fmoke con- centrations are found. This study (75) found a high prevalence icrude and age-adlustedl of crude chron c bronch t3s and cor purmonale f 10-30',:1. A str,k ng feature was the sim- ilar ty of rates in men and women, The difference in prevalence rate between the sexes was not stattsU• csny significant in any study area (P > 0,10 - > 0.98). This conflicts with most other ;tudies, which have shown a lower prevalence rate among women. Tobacco smoking is common in both men and women in all but the urban area, where the smoking rate among women was only 14%. In all areas. however, women were light smokers fless than 10 ngarettes or equrvalent per day). Heavy smoking among men was much more prevalent and the difference was statist cally signlficant ,n all three rural areas fP < 0.05 - c 0 0013 although not in urban Kathmandu This suggests that the high pre- valence of chronic bronchitis in women is primarily occupat3onat since women engaged in cooking meals for the family are exposed for proportionately longer hours at higher concentrations of domestic smoke pollution than men. The difference in smoke w.r..w.u..er«r o„»o, 2501154756
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- 130 - exposure hours was significantly higher IP < 0.0011 in women in ali the study areas. In the hill vdlagesm a stat+strcaiiy significant iP ! 0.0011 pos t3ve correlation was found between prevalence of chronrc bronchitis and exposure to domestac smoke poliutron in both smokers and non- smOkers IFrpi1. This supports earlier studies in India and Papua New Guinea (i6•T91 wr3mh suggest• ed the poss t)rllty of a relationship between chronic bronchatis and domestic smoke po,luttOn. The trend of increasing prevalence rates with increasing smoke exposure persisted even after elimination of the age eHect (20). A srmdar stat strcauy significant correfs• tion was also found in other study sltes. In the mountain vrllage, it was not possible to compare the prevalenct between exposed and non•exposed groups, because everybody was exposed to do- mestit smoka trom space heating. Unlike in other erees, hovvever, many were exposed more than !8 hours per day. This provided an opportunity to test for an effect at longer hours of exposure. A s3gnlfi- cant correlation between bronchitis and smoke ex- posure was noted also beyond € hours of exposure among the smokers of both sexes. Hence, thert seems to be a dose•response relationship between domestic smoke pollution antl chronic bronchitis. All the cases of chronic cor pufmonale identified in this study wert complications of chronic bronchrcrs. Although most of the women Smokers were light `werna "eanh 0+qsnke3,on ature rtsZrrarorr rn/Kr,one in r~roron flbss e, Af4 3 0l t*e Resmraroh Infecr.ons Progr•mrr,e a~d Ine r•rogr.Tme Suaoon Se+v+ce Gen.w. tss? smokers. the stuoy recoroed similarity of prevalence ot chronic cor pufmonart in the two sexes. This suggests that domestic smoke polJut3on is an rmpor• tant factor in producing cot pu+monale Childhood aCute respiratory rnlecrrons lAA!!. Se- tween A and 5 m;313on chddren c$ dre in the world each year from ARI, mostly ,n develooing countrres Most ARI studres have focused on the important issues of microbral causative agents. case• management with antrbrotocs, and eNectweness of vacetnaUon. Research on risk factors has been ludged to be of lesser tmponance in spite of the dom nance of rrsk•factor reduction in the h stary of API control in the developed countr,es. Domestic smoke pollutran has been assumed to be •n Impor• tant risk tactor for ARI in many parts of the devetop• rng world$ but there have been few studies. Par- ticulary of tht relationship with pneumonia, whreh is nearly always involved in fatal cases. In a study carrled out before 1980 ,in Papua New Gu+nes. Anderson 1271 failed to f+nd an effect of environmental differences. rnclud+ng househola smoke, on acute respiratory symptoms among schoolchrldren. In a study of younger chrldren in South Afriea. Kossove e22) found that 70•, o! Zulu infants wrtn respiratory symptOms lived in npuseholds with Cookfrre smoke, COmpared to 33'i of a partlally matched group wno did not have such symptoms This was significant at the P:0.005 level, altnough there was no significant d+fierence in me maternauy• reported exposure times for the groups. No con- founding factors were 3nvest gated. F7G.I PREVALENCE OF CwRONtC ©RONCMITIS IN NEPALESE MILL YILLAGES ACCORDING TO SELF-REPORTED DAILY TIME SPENT NEAR COOKING lfEATING STZ7VE. AROUND 1%s' PREVALENCE DE LA E6tONCNITE CtIRONtOUE DANS LES VILLAGES NEPALAIS DE MONTAGNE EN FONCTION Ot! TEkiPS PASSf WAR JOUR A PROXIMITE DU POELE (CUtSINE+CMAUt=FAGE). VERS 1034' a-0• +.1s :}s .. w«rs r,ee wwe.. ea ens.n ra r rw r iwr r..n v+.wf -r.+ r,rerf  u.~ rr~..n © hwss -srr+n ... -w~.wr..w -*~'se "+er • TM r'lr8 OaoMd'{ Me sVr4rta+4 fyMMVJ.u ,e.0007, w/ V-PMS H! IN 0MVn M'r N*W7 I}A - u" 1YROM rl/M eSr lrR*M/M.e fwMi/ul rA oot, .ws I ,"-++ an ,~ .r sa. s r_~ I. " ..... pft rto+ ++r wwww wr.r N+. ..w O r»ec 2501154757
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As part ot WNO-sponsored indoor air pollution studies in Kenya and the Gambu (23,"1, ARI incr dence in Kenyan Children c 5 was monitored b+- week)y in 36 houses for 92 weeks. During this period, stationary indoor 24-hour monitoring was conducted twice in each housew for nitrogen dioxide and suspended panicutates. Although respirable par• tUCUlate concentrations wett quite high /maan of 1 t mfl,mJl. no correlation was found between ARI ,ncrdence and indoor concentrations of erther poi- lutant. or with eaposures of the Ohrldren, as deter- minetl from the ConZentratrons and time spans con- structed by interviewing the mothers. tNoreover, the measured concentrations were quite homogeneously distributed among the households. Indeed. the rntra-household variation between the two measurement days was greater than the rnter- household variation, although households were randomly chosen from four groups stratified on the basis of h0use characteristics, roof type and kitchen arrangement. thought to influence ventilation, and tnus ,ndoor air Oualtty. As the authors point Out. given Ihe apparent Iack of natural variation in tx- posure among nousenolds, it would be quite difficult to esiablrsh smoxe as a risk factor with this type of study design. in the Gambia. on the other hand, where indoor woodsmOke levels were also high, but homo- geneousiy d stributed. there seemed to be significant d,fferences in exposures because some young children are carried on their mother s back during cooking Based on a multiple logist c regression. Ca'npbel) et a1 i?IJ report an adjusted odds ratio of 2 5 fa 8a So1aeS of breathing difficulty among 280 children carried by their mothers The Only other signif cant risk factor was paternal smoking. A sem-9uantrtatrve epidemiological study was ton- ducted in Nepal by Pandey et a1. (25). to assess the relation between maternally-repor2ed hours spent per day near the hearth by infants and ch ldren c 2, ano ep,sodes of Iife-threatenmg. moderate and severe ARIL in the study area. a hill region of Nepal, tradit onsl stoves burn nfl biorrmass fuels. ma n)y wood and crop res dues. are used for Cooking and heating in unventilattd houses with no chimneys. *ne area is totally free from industrial pollution. The first Substudy was conducted during a s+x- rs+ontfi per od in 1984 A statrst calfy s gn,ficant -P ~ 0 01) assocrat on was found when the exposed group was compared with the non-exposed in the two age strata i.e. c 1 year fF,g. Is1 and 1-2 years. In oraer to confirm and validate the findings, an addi- t,onal three-month substudy was conducted in the same poputat on. This Substudy employed separate groups of observers to determine AR) ep sodes and smoke exposure trmes, thereby assuring igreater degree of independence in observation of the two variables A statistically significant (P < 0.011 associ- at on was found in this second substudy as well rf+g. 2b1. There were no obvious confounding factors that might account for these findings. 5ocioeconomic condition is not an important factor as more than 98% of the population live within a subsistence , w0"0 M!)Irn Oqam7J1,0n MbOOr sn OYIriM M rHe l1yse Irea. rne Gume.a iOocu+nenr GEr+eSr+EaLS ws+O's'EP.la 3 tsssr w.n0. J i Lt+er. # M Iftu N+awncs of au sarwan an -unO'opK1/ yorlnNror{ 0 cru41ren1 shanQRM WdfGi uni. .enIrr. 1917 IGr06wre rMS+er ta+ C+Mee+ar. :+v.~ i-avt wwr_ a nMOi economy, and nearly a11 the houses are similar in eonstrucUon. This preliminary study seems to suggest that domest,c smoke p011ut3on is a risk factor of ARI. As -th all available stud+es. however, there were insufficient resources to fully monitor exposure, measure and correct for confounding vari. ab3es, and to conduct the many expensive and time- consumrnq qualrty•eontrol procedures needed tor ful)-sUJe modern environmental epidemiology rn• vest+gatrons. Cosl - East Asia In China, Coa1 is and will rema n for decades the main energy source. Particulates and sulfur Oxides emitted from coal combustion are two of the ma n urban atmospheric pollutantsIn $hanghat, some 6% af total coal consumption is used for domestic cook- ing, making 4 the most rmportsnt urban cooking fuel. For example, until 1987 Tian)in was the only c ty where all the families used gas stoves and in Beijing, only 70•1% of the families used gas or t+que- f,ed petroleum gas, while in $han9ha about half of the population use toal-cake stoves Little indoor air quality research has been done in rural areas where most of the population uses crop residues and wood. Research On indoor pollution and its health effects was rnitiated in China towards the end of tne 1970s and over 100 papers have been pub)isneo f51 on the subiect. A series Of epitlem olOgical surveys have been carried out to evaluate the effect of indoor pollution on human health. In contrast to stud es in developed countries. the gas-user group is usually tonsidered as the unexposed control group. and the coal-user group as tne exposure group. Immunolo9iCS7 function. The influence of indoor air pollution on immunological function was rnvestegat- ed in grbups of pr,maryschool students aged 10-13 exposed (or not) to coal smoke at home and at school 1251. Compared to the control group. the amount of SIgA in sauva of the exposure group decreased by 32.5%, and the ict vrty of IysoEnzyme by 17.3'1.. There were no difterences in d-stributron of age, sex and ETS exposure between the groups tP values, ell > 0.051. Wang & Chen monitored the immunological pars- meters of primary•schoo3 pupils from families using different fuels for cooking: The resulls were stat+stic- atly significant 1< 0.051 for white blood-ceu Count (mean reduction: 13y.). saliva lysoenzyme t13•..1, transfer of lymphocyte l50'>.1. !gG (29%). tgM 128%) and IqA f5dY.3. but not in the Pt1A skin test. Carboxyltaemoglobin lHbC01. The blood f'lbCO con- centration in women using coal stoves was 2.1 s 0.9%. compared to those using gas stoves at 1.+1 t 1.0% iP < 0.01). Women using coal stoves without chimnEys had a.3'!., while thOst usrng Ch3m- neys hao 3.0% {27). A study by Mu & Liu of 450 suburban schoolchildren < 13 near Beijing f28) found significantly higher HbCO levels in those living in traditional housing where pit stoves were used for heating and cooking, t:ompared to those residing in modern buildings with stoves and Chimneys. At 41% and 2.8%. how- ever, both groups vrere high. The authors compare 2509'154758
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-732- FtG. 2 ACUTE RESPIRATORY INFECTIONS iN INFANTS (0-1) IN TN£ HILL REGION OF NEPAL LISTED BY SEVERITY AND MATERNALLY REPORTED DAILY TIME NEAR STOVE' INFECTIONS RESPIRATOMES AIGUES CHEZ LES NOURRISSONS (o•t AN) DANS LA REGION DE MONTAGNE Du NEPAL, CLASSEE5 SELON LA GRAW7E ET SELON LE TEMPS PASSE PRES DU POELE CMAOUE JOUR AU DIRE DE LA YERE' A S.uc on;a rno^rs ma ooto=n 798+ 2i3 Rss3 - Su h taee des ornes wri+i~ i^ 196a s r une prrst D! io moe ~3 rsxr•sv~c / 200 _ r n - I!0 ~25 ~td ats aso a 2s 11 oz 7, ...~.L_~t 1.10 1311, aa a 4 4. .a0r W 9/t !1. M~ f.! - i'MIVa Mme" lt V. MM0 Y!M0 @ Saseo on tMree montns' caca cojj.neo in 19e9..atn tne ssme populacion (217 infantsl ts7t +ntn stDarait ttaP+s oiag++ostfg ARI ar4 oeceM+jnmq e=posure - Sur Ia Uase oes oonnees recvvl~ts en 1989 sur une penooe oe ttatf ino.f aa'7s li rM}+b p0ou1at1on 1247 noumssons). aes eau+aes oisrinents Can3 cna,qees ot ouqnost quef tes IRA tt Oe txtermmer rtsposmon %f9sn.0 'aat 1n, M7 NI Ow. - -4V" Y"M Y IM i iMM am IMr n n i4a an" Km11-w bI1ft tYWe 11 iYMrlr rSIM WaM oI - Ci ~1OMa Mo Ni fo ao ews qrs.w r.m Me . Cr V+"M wwe r M M ~ nrswws.a~.+ra~+ws.~~+s~Mi-wsr~wss..nqnNraw.rsrsN.r+tf1 these results with an earf3er urban ftudyl wlfsre HbCO levels of a,3x. 3,0% and 1.1% were found for residents in homes heated by stoves without fiuWs, by stoves with flues, and by circulating hot water respectively. This study also found other sffeots. There were siyn ficsnt differences in the incidence of lower respiratory diseases among girls iRR.3. p. < 0,05) but not for boys nor for upper respiratory diseases. Small or non•s gn3ficant d fferences wert found for immune and eye responses and lung functron. after correctrng for height, age, werght, family income and parentsl smoking (28). - Chane >< M, /An a0•0.m oroqKl/ siutlY pn neeo. M io+wna+). f.eond Nstiona Conrer.nee .n fnv,roa»nenw Nsem. OnaD.+ 1064. Ne++pn9 t1n Lhintia. Although sma3J•scale combustion of all coal and biomass fuel is often associated with high CO emrssions, poor combustion of a1l unprocessed b9o- mass and high•volatile coals also emits large amounts of hydrocarbon serosot and gas. e.y. eldehydes. A1thDugh these may have long-term health effeets because of the intense irritation they Cause, they act in the short term to warn when CO concentrations approach acutely toxic levels. In other words, it is extremely rare for someone to die from acuts CO poisoning from such tuels. Even though measured CO concentrations can somebmeJ approach dangerous ievels. the irrttst,on due to hydrocarbons will awaten householdeR and prompt them to escape or open a window (4). +ra.r v.+r. w«. aw .w.. af r*ww 250'i'I 54759
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- 133 - Unfortunately. this is not the case with the three principal !ow-v0latile solid fuels' charcoal, naturally low-volauie coal such as anthracite, and processed idevolat33i=edl coal. These may release no more CCt than the high-volat le soLd fuels. but they do so with little of the irritating hydrocarbons that provide warning. As a rasutt apparenNy, hundreds if not thousands of people die every year in northern China, Korea. the Islamic Republic of Iran and other developing countries where overnight space hest+ng is provided by such fuels irnafn3y coall, along with excessive leakage of combustron gases into living areas. compounded by poor household ventilation. A study in Korea, for example, has shown a strong seasonai var at,on in hospital admissions for CO poisoning, peaking during the cold season where heating s used (29). Mortality +s not the only effect- hrgh, but subietha3, exposures can cause serious poisoning. Lung function. Li b}iongr monitored the lung func- t,ons /FVC. FEVI, FEV1•.1 of 213 women aged 50•70 years, including 167 women us ng coal and 46 using gas for cooking. Even after adlustment for potential confounding factors, i.e. age, body wefght, he ght and ETS, there was e statistically significant dff'fer- ence between the coal group antl the gas group in all lung functions tested. In another study, the FEV1IFVC of Dersons using coal Stoves was lower than those using gas stoves, while tne reverse relat onship was found for tvfEF25. MEF50 aRo MEF75 Thfs was possibly due to higher NOx concentrat ons in homes using gas. In Xuanwei County, Yunnan Provtnce lsouthern Chinal. the airway resistance of farmers snd school- children in homes where poor•9ratle bituminous toal waS used for cooking was higher than in homes where wood and straw were used for cook ny IP < 0.001) G?01. Respiratory syrnptams and non-csncer resprryrory d,seases There seems to be an increase in resp ra• tory symptoms and prevalence of respiratory dfs- eases in coal•usrng families, A studY was conducted in two areas of Shanghai with populsUons of about 77 000 and 17 000 respectively. Two samples were selected, using cluster sampimg 1 316 usfng coal- cake stoves and 721 using gas stoves. The respira• tory symptoms and prevalence Of resprratory d,s• eases were found to be 79% and !4'/t, respectively, for people using coal stoves and gas stoves 1P < 0.05). The prevalence Of respiratory d seases among housewives aged s0•65 are 50% and 40%:, re- spectrvely, for coai•us ng homes and gss-us3ng homes, where P < 0,05, and relative risk for coaj- uvng housewives is 1.9 (28). The prevalence of common cold smong persons using stoves with or without chimneys were 22% and 52% respectively; RR-2.0 (without chrmney), attributable risk - 25'. f311. The prevalence of chronic bronchitis, em- physems~ tough, productive sough and breathless- ness in women using coal stoves were significantly higher than among those using gas stoves There were no significant d0ferences in the prevalence of coronary heart disease, hypertension and a tight feeling in the chest between the coal- ano gas•usrng groups. Another studv ,' carried out in Shanghai on 12 037 people, using the American Thoracic Society DLD•7E questionnaire, found that in areas where atmos- phenc pollution was l,ght. the prevsknce of COLD was 9 6% in the gas-user group and 15 6': in tne coal-user group In heaviiy-polluted areas. these prev- afences were 12.8% and 17.3%, respecttvely. Multf- variate analysK indicated that indoor air pollutfon had a stronger impact than outdoor air pollution. Another survey of respiratory symptoms and dfs• esstt was earr ed out among retired women and nonemploYed women aged A5 years and over 1321. Of the 393 women who responded to the auesnon- naire, 186 used gas for cooking and 207 coal Indoor pollutant toncentrations typically found in each type of home were determined, based on small represen• tstive samples. The results are listed in Table 7. • L,. L & Monq C. J 1Xrtehtn a.r poiruhon ana }rs Marrn tMtRSI SnangM. rNee'cai un,wrs,h. fsH iGr.owu tntsusi Ifn Cn,nsal LIn. N S t+ st frtaUr,on a/ nr po+uvran ano >+wnsn nfmn rn a +,qntr dtns,rv res,atnr,*l 0104 af SnanqnA,l SrIT+oo..0+n on {n-onTtntai Mtann, Tuyu.n. 1913 itn Cn,ntaa I .bnq C j a+ aI t5rya,es on .,r you,n,en and n: ,rr,aaa an ntann rn SMnpM,1. SMnsnar Meau1 unrrnsnr. tsss an Cnwaer. In order to determine whether factors other than indoor pollution isuch as age, living stanoard. tou- cation. ETS, kitchen Style and living space per per• soni were important influences. a multifactor logistic regression analysis was conducted. The result showed that domestic smoke was an rmportant con- trnbuttng factor to chronrc bronchitis, emphysema. TAiIE 1. PltEVAIENCE OF RESM/1AT07lY SYM/TDMS AND DrfEAU; IN WDMEN UsrN6 ClFF£iIEWT FUEtA FOfI C001CIN4. tlaE TAtit.EAU 1, f 11tVA1ENCE DES SYMITOMES ET MALADIES RESMRATO/REf CNF2 LEf fEMMES tJnilsANT DIFFEi4ENTS TYPES DE tOMiUSTiiLES POUR LA CUISINg. tlES p.w.ww~w~wM G.awar.usitalur., Cw„wenrr~to7cewf, y.yty" now*,M ~j.w~y~d,vnlM~alI1MtJ41 C-YytN+•.NMMCN/fM1107W. f1IM-MI 0 M.,~.tr~M,ntrt % IN„/VM-NM~ • ti~ -4M.M ti +4ttrsa - Asttvey ......... . . . . i civOr.c txtx+CV:u - ertorrlria e*aoniptie 22 g onc*ooaatatan . . . . . . . . . . . . . 3 En+onrssrna - EmOr YsMte i Camary n.an bsaaa. - Careeoatme manaeynne . . . . . . . . . . . . . . . . 27 wyflat-nuon ................ 40 Ca+9n - Toua ......... .. .. _ 33 >xso.etorauon ...... . .... .. 2. Ct,est tqntneu - GinM resaraton .-.. 55 r+rV1tnw ot t,raatn - Essoutn.ner,l ... t! 3.3 ts 72 22 >D 05 ttti 31 ?s6 75 <DD1 144 13 623 a; <D DS 215 21 10.1 7.3 <00+ t..S 25 121 0.611 :oo 03 72.3 i6 31.3 0 03 >0D5 117 23 ipt 191 <001 112,111 53 254 75 c001 296 n 372 2.1. >005 9.611 53 25,111 13+ cOpOt t++. ~1.r..a +aN - A.rs iin. rML.o aws, wrM, e rtMN 2501154760
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F bronchod3lataUon, cough. expectoraUon and short- ness of breath. TResa conditions were 1.l1-4.5 times more common among the group exposed to coat smoke. No s,gn+f+cant difference was found for coronary heart d+sease. In Hong Kong, Koo et al. (33) found small 110-20X1 but stat+st+cally s+pn+ficant differences in nttrogen dioxide exposure levtls as well as reported resp+re- tory symptoms (allergic rh+nitis and bronchu+sl among non-smoking mothers in homes using piped gas ilower exposurN for cooking, =ompared to those using kerosene or bottied gas. A similar eNect was found for ancense•burninQ and kitchan ventilation. but not for rrmosau,to coifs or ETS No effect was . TAtLE 2. LUNO.CANCfR OODS RATlO 1014 Di fMOKiNG AND COOAING - CASELO>lTftOl ANALystS. 442 rArlkti. 1113111 TAtt.f..s.V 2, ODOf RAT1O 30R1 DE CANCER DV POUMON PAR EzPOSr110N AU TAIAC ET AUx Wra£fs of CUISINE - ANALYSE CALTEMOINS, ee2 PAiRES, ties r CA r : oill • 11) s-NS-E•NE ,..... t.0 t o t2/ NS•NE .. ...... 031 rOC6 031 >005 Ctl S•N€ .......••• a+ <0 01 06 xo O6 Nl NS.E .......... t.a aOCS 3 a <005 (3) s-E ••.•• 42 c001 58 <o.0f , s• found in children. 4s Canrer. fthough the lung•canar rfsb Df Dcw• ss.+e. a......rr - s..... un .•pat+onal exposures as wllt as act+ve srnoktng, ind to lesser extent ETS, have bNn extent+vtly document-_- ].' the rslatlon_betwesn lung tancer and ambient 'irlpollut+on remains uncertain. Indoor pollution, however, is now starting to be linked to lung cancer, especially among 'vi_cmen co_oking over coai-fired stoves, although their level of cigarette smok+ng~and occupatUona3 exposure is much lower than men's. showed that a hi h coal{onsum tnon index iHCCt .10.61, indoflr smo ollution in w+nt r : 75. 1 and low ceihnq height of the living room S.12.51 were the mam nsk actors for female luno adenocarcmoma. !t was further conf+rmed by +ndoor air monitoring that the average s+r con- centrat,ons of total suspended particulates ITSPI and benzotalpyrene in bedrooms in winter were 4.4 and 27 times higher then the respective maximum allow- able air concentrations in China. No s+ ndioant tAr- relation was found bttwesn fems_{ u q 6n carcinoma, and ciaarene smoking and €TS. In another Xuanwe+ study, the standartl+zed lung- cancer mortality in 1973•1975 was 26 taer 100 000, hiflher than the average urban lung-cancer mortality in China. In Xuanwe+, lung-cancer prevalence was different in various regions, the highest being over 1 S0 per 100 000, wh le the lowest was under I p!r 100 D00, a difference of about a factor of 200. Although rare today, in the recent past hiflh-ter Qituminous Coal burned in open pits was the main domestic fuel used in hagh lung canclr qrevafence r o ns while ant r.cite coa! sn woo were us in iow- reval~ance r!.9 _i0,,.n~~s. The prevalence 0 unfl cancer 1mers was n+grler than among people in other occupations and there was lutle difference between sexes. This evidence suggests the presance of a stran carcino-enicfactos unt~To-Tun-canEFr +n nonempioye women I esearc Involving indoor air monitoring, ep+dem oloqica3 studies and animal exposure tests in siru have been conducted by the Chinese Academy of Preventive Medical Sciences and local public health and ant -ep+dem+c stations with assistance from the United States En- vironmental Protection Agency (39, 40). In Hon Kon , however, no si nificant association w s f und bltwsen iun tancer an eoakln us s (tf/ or a2/ The indoar•pol utant concentrations were mucF~fess than those found in the above- mentioned lung-cancer studies in China. Although there have been reports linking domestic smoke with Ihe high rates of nasopharyngea! Cancer among southern Chinese populations 143, 441 and in other proups, e.g Kenya W, 46). most reviews have con- cluded that the risk must be small or non-existent compared to risk factors Such as diet (a 7). Ftuoross Increased ffuoroses induced by high eon- centrat+ons of fluoride in indoor air and food ong- inating from coal Combustlon has been rtporled recently (ad-517. In the suburbs of Xiangtan lHunan Provinoef the fluoride concentration in drinking- , water was less than I mg/htre. but in coal it was Xu et aL (3t/ analysed female lung-cancer preva- lenpe in 1~Chinasa metr ol+tin artai. eaeh with s papulat on over 500 000 and located at various lati- udes. The found that the correlation coe +c+ens E n ma e 1 n{anter rtvilence an latttude yyere statkSUCaIJV s30n+flcant. he h+4her the latitude, the higher the lung cancer prevelence. _Ying tt al:' compared teveril factors with t_h_e_h+Oh and low lun -Cancer revaltnC! re ions m uhan istanoard zed rases 26 vs. t p!r tOD 0003 to +nd that there were s~ ni icant d+ .erences in stove es and dens+ty, sul ur d ox+dt and nitrogen oxides, but ntt for esrpon monas>".-- 171 uamg2hou, titsre were 349 housewives amono 1 2femaie lun -cancer deaths l351. These women 128G) had no prev+ous occupat ona exposure, a, o t em wtrt non-smo ers, and none seemed to be tx osed to sigm ~cant outdoor air pollution. he _ep+dem+o oq+ta survey s owa t at ema,alun9• n r c rrenc was rt ated to ex osure to coal mb sUon and cookin 1351. The investigators monitored ketchens or sUSpended particulates, de- posited dust, and beniolalpyrane in deposited dust. They found las expected) that concentrations were much higher in k,tchens using coal compared to those using liquefied petroleum pat for oooking. Based on a case-contral analysis of 662 deaths (446 males and 216 females), the lung-cancer odds ratio 10R3 of smoking and cooking was analysed and is presented in Tab7e 2 f357. Exposure to cookin4_ was ,Spy,nd to b! an imooRant Contr+butln sct f to fem~~ lu_n~~n r u_i no_ito male iuno canq~r ombination of smokin9 and cooking exposure has a lsynergistic effect on the r+alencq of lung cancer in ~ both males and fsrnal Another matched casesontrol study and measure- rri ; of'indoori+r po7 utlon was urrie_ out in a northern Chinese Ci {Harbin) to anal et risk factors 4si fsmala auny adenoearcinoma f 1. he resutts • rine. X n a/. IrM r.Yr1on ar ,ndoow br 9o+rwwn ind flwnan Msat+ • a a+a•++rY MaArt waifnpt> 9n Clt'niyl *nr,rennHmal r.,un. lss3 i/n cnny.e,. •..._.s..w.f ..- .unW a l+Zr1e+ 250ll54769
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r 190 330 mgrkq. Fluoride concentrauon originating from coal combustion was 0018-0.066 mgimJ in indoor air and 1.9-3.3 mg;kg in vegetables. The prevalence of dental fluoros+s thert was as high as 35% in residents of all ages. In a neighbouring area, the prevalence of dental fluorpsrs in a control group cook,ng with wood was only 4,9X. 1181. In the suburb of Luoyang (Nenan Province) the fluoride concentration of coal was 370-610 mgfkg, and the indoOr-air fluoride concentration was meas- ured at 0.016 mg/m3. The vegetable and grain fluoride concentration was 0.95-3.4mgikq. This sn- creased to 2.7-14mg.+kg after a half-year storage period indoors. There were 1 4$6 persons suffering from fluorosis among 2246 persons aged over 6. The prevalence rate was 66% f491. increased preva- lence of fluorosis due to coal combustion in residents has also been found in Xunwen (Sichuan Province), Ankang (5hanxi Province), Benxi (Liaoning Province) and Huangganq tHuba Prov,nce). Stroke A group of 957 men were followed for 12 years in a study of risk factors for heart disease and stroke carried out in Shanghai i521, During the study penod. 24 subjects died. In addition to high blood pressure. age and smoking, the study found ex- pasure to h0usehold coal smoke to be a significant r sk factor. A dose-response relationship was found with the relative risk of heavy exposure iorrly coal usel of nearly 11, after correction for the other major risk factors The sl ghbexposure groups lus ng both gas and coau had a relative risk of nearly 4. Conclusion Ava;lable ev dence in the devt3op+ng world would seem to argue strongly that indoor air pollution from cook-fire smoke is a risk factor for chronac lung zb3e)Se in adults, particularly women, and acute reSDrstorlr disease in young children. In addition, coal smote may be an imporiani risk factor for lung cancer in women. The total number of people ex- -135- posed to high concentra"Ons of smoke is likely to be several hundred million. However, too few resources have been allocated to such studies for it to be poss ble to quantify these eNects. Such efforts are needed, however. in order to determine the effectiveness Of smoke-exposure reduction measures in compar son with other ap- proaches for preventIng or mitigating these dis- tases. in particular, there is a need to link detailed sp - dem+ological study designs using internat3onally sc- cepted diagnostic procedures with detailed and sys- tematic exposure determinations. This is not sasy to do with cancer and chronic obstructive lung disease, since exposure histories going back severai decades must be established. One of the highest priorities for indoor air pollution epidemiology is to initiate a study of the risk factors for AR1, because of its importance as a cause of early chddhood morbidity and mortality in many developing countries, and in view of the high indoor exposures that stem to prevail in many areas. A longitudinal {ntervent10n study lasting at least two years and including all seasons before and after intervenhOn would most likely lead to resutts that are scientifically sound and useful for designing large-scate inten+ent,on programmes (53). A growing trend among those concerned with en- vironmental epidemiology is the reabLation that, in order to understand the impact of pollution on health, it is necessary to monitor dwelling places rather than tust the ambient environment. Total ex- pt?syra' assessment IS the term for tuch efforts. which are beginning to reveal important sources and Cantrol measures different from those on which past efforts have focused fill. Indeed, from a global stand- point, the present baiance of research, monitoring and control efforts in air pollution should perhaps be sh hed towards households using unprocessed solid fuels, which is where the largest number of suscept- ible persons can be found. SUMMARY Of tht four principal categories of indoor pollution lcombusuon produtis, chemicals, radon and bio- logacals), tKtarch tti developing countries has focused on combustion-generated pollutants, and principaliv those from sol3d-fuel-1ired cooking and heating stoves Such stoves are used in more than half the world's households and have been shown in many locations to produce high indoor eon- centrat,ons of particuiates, carbon monoxide and athe+ combustion-related pollutants. Although the proportion of all such household stoves that are used in poorly ventilated situations is uncertain, the tota1 population exposed to excessive concentrations is potentiatiy high, probably several hundred million. A number of studies were carried out in the 1980s to discover the health effects of such stove exposures. The ma)ority of such studies were done in South Asia in homes burning bromass fuels or in China with coal-burning homes, although a sprinkling of studies examining biomass-burning have been done in Oceania, Latin America and Africa. wr~w.e.wn_nnea Of the health effecis that might be expected from such exposures, little, if any, work seems to have been done on low birthweight ano eye problems. although there are anecdotal accounts making the connection. Decreased lung function has been noted in Nepali women reporting more time spent near the stOve as it has for Chinese women using toal stoves as compared to those using gas stoves. Respiratory distress symptoms have been associated with use of smoky fuels in West india, Ladakh and in several Chinese studies among different age groups, some with large population samples. Acute respiratory rnfeCtion in children, one of the chief Causes of infant and childhood morta3ity, has been associated with Nepali househo3d-smoks exposures. Studies of chronic disease endpoints are difficult because of the need to construct exposure histories over iong periods NtverMlless, chronic obstructive lung disease has been associated with the daily time spent near the stove for Nepali women and found to be slevated among coel-stove users compared to 1 1 2501154762
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136 - gas•stove users in Shanghai. In tontrist to early reports, there seems to be ltttle or no risk of rtaso- pharyngeal cancer from cookttove smoke. Several studies in thina, however, have found smoke to be a strong r sk factor for lung cancer among non• smoking women. In addition. severe fluoros s hss been observetl in several parts of China where cOSl fluoride levels are high. The high indoor concentrations and the potentially large 1also poor and thus vulnerablet populations at risk, argue for more resources to be devoted to ep dem3ological stud,es of large numbers of expostd populations, using appropriate ouafltytontrol meas- ures in order to generate reliable qusntrtative dose- response informsoon. In the meantime, however, enough is known to warrant household. Communtty and government efforts to reduce exposures through education and introduction of improved stoves. cleaner fuels and enhanced ventilation. RFStlME= Pollution de 1'air it I'interieur des habitations dans !es pays en diveloppement Des quatre princjoaux tYpes do potiution 1 I'interieur des habitat,ons Iproduits de combustion, substances chimiques, radon at substances biotog,quesl, Ia re- cherche dans las pays en developpement a privilegii les produwts de combust,on tt notamment ies pol- luants resuitant de I'utiIisat on de combust bles soli- des pour Is cuisson *1 le chauffage. Les postes incnmines sont en service dans plus de 1a moitlt des habitations du monde ei il a ete prouve tn de nombreux endrorts qu'ils etaient a Ibrigme de concentrations elevees de matieres particulaires, d'oxyde de carbone et d'autres polluants lies s la combustion, 8ien que I'on ne conna:sse pas evec precision Ia proportion de po+<les ainsi utilises dans des focaux ma aares. le nombre total de personnes exD.Ostes a des CarrZentratioes e=Ltssives de poit- tuanu est eleve, prcaaab~ent ptsrsieurs cent,sints dt millions. Dans Ie courant des annees 80. plusieurs etudes ont ete consacrees sux e+fets sur !a sante de !'exposaion i ces prodults do combust on. La plupart ant ete condunes en Asie merid onale dans des habitations ou sont utdises des oombustibies tires de la bio• masse ou en thine Is ou I'on utifise du charbon, bien que ctrtarnes etudes sur I'utilisat on de Is bio- masse a ent ett fattes rn Gcsante, tn Amenrtue lstine tt sn Afrique. Parm Ies effets de ce type do pollution qui peuvent etre redoutes, ii semble que !'on n'a t prat quement pas ou pas du tout ttudie I'insuffisance ponderale a la na,ssanoe et Ies problemss ophtalmolog3ques, blen que Clrtains comptes rendus anecdotiques !as• stni Is tesat+on e*+tre cts problemes et ct type do pollut+an. Une diminution do Is foncu0n putmonaire a ete rNevss chet des femmes nepalaises ayant signsle passer beausoup do temps aupres du po#1s ainsi que che2 des femmes ohinoises qui utitisent des ouismieres a charbon par rapport i celles qui ut lisent des cutsinieres a gaz Des symptdmes do detrtsse respiratoire ant ete associes s I'utilisation de combustibles prodwssnt de Is fumet dans I'puest do I9nde, au Ladakh et a I'issue de ptusieurs studes dhinoises ponant sur difterents groupes d'ige, eer• taines aupres d'tchantillons importarits de popula- tion. Des cas d' nrections resp ratoires sigues ches Its enfants, I'une des pnnCipalts causes de mortaltt6 inisnto-tuvenile, ont ete associes a 1'exposition a Is tum4t dans des hab tatlons nepataises, d'apres ie temps passe par Ies enfants supres des posles. Les ftudes sur ies maladies chroniques sont diffici- les car iI est necessaire d etablir des antecedents d'exposiiion sur do longues periodes Neanmotns, Is rnaladit pulmonalre obstructive Ohron3que a tte as- societ au temps passe Chaque lour aupres du po4le pour des femmes nepala)ses et son taux d'rnadence a ete juge eleve parma les ut l satrnces do polles a charbon compare aux um satrices de po!!es a gat s $hangnai. Contrairement a ct qw avatt ete prK!- demment ind que. ta lumet degagee par les cuisi- nierts ne presentt, sembie-t-U, qut peu do risous do cancer du rhino-phsrynx. Toutefois, plusieurs etudes rnentes tn t:hine ont mOntrtt que la fumoe ltait t/n facttur de risque important pour It cancer du pou- mon chei les iemmes non-fumeuses. En outre, des oas graves tie fluorose ont ate observes dans plu- sieurs regions do Ch,nt ou Its taux de fluorure dans Ie chsrbon sant altves. Lss concentrations slevees de pallusnts s I'int.rieur des habitations et I'importance des populations exposees tegslement pauvres, donc vulnersblesllus- tif ent que des ressources accrues saient consacrees a dts etudes epidem ologiques d'echant,flOns ampor- tants de populat on tn prenant its mesures do cbn- tr81e do ia qualite necessaires i I'obtenUon do don- nets quantitat,ves fiablss sur Its rapports dose- rtponse. Ce1s etsnt, et que f'on sait devrta,i dljt suH,re s inciter Ies menages. Ies communautes et Its gouvernements s retloubler d'efforts pour reduire I'exposit,on i ces types dt pollution, par 1'lduuuon tt Yintroductaon de posles arneliores, do combusti- btts plus propres et do me+ileurs systemes d'sers- tion. REFSRENCES- RfF~RENCFS 1. $AnatT, J- M. ta .,i. Health effects and sources of indoor air pollution. American review of respira- tory d;sease, 136. 1t86-1508119871. 2. SMrt>,. K. R. indoor air pollution and the pollution transition. In: Kasuga, M. ted,l. Indoor.rr auslity. Berlin. Springer Verlag, 1990, ISupplement to the International archives of tnvironmtniaJ hea/rnt. 3. SMmt. K. A. Total exposure assessment: impli- cations for developing countries. Environmsnt: 30 001; 16-20: 26-35 119681. a... ..w.. .,rw &.,.. .w s f..r6' 2501154763

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