• 沒有找到結果。

Climate, traffic-related air pollutants, and asthma prevalence in middle-school children in taiwan

N/A
N/A
Protected

Academic year: 2021

Share "Climate, traffic-related air pollutants, and asthma prevalence in middle-school children in taiwan"

Copied!
6
0
0

加載中.... (立即查看全文)

全文

(1)

Children's Health

Climate,

Traffic-Related

Air Pollutants,

and Asthma Prevalence

in

Middle-School Children

in Taiwan

Yueliang Leon Guo,1 Ying-Chu Lin,1 Fung-ChangSung,2Song-LihHuang,3 Ying-Chin

Ko,4

Jim-ShoungLai,5

Huey-JenSu, Cheng-KuangShaw,6Ruey-ShiungLin,7and Douglas W. Dockery8

1EnvironmentalandOccupationalHealth, National ChengKung University, Tainan, Taiwan;2lnstituteofEnvironmental Health, National

Taiwan University,Taipei, Taiwan;31nstituteof Environmental HealthSciences,National Yang-Ming University,Taipei, Taiwan;

4Department of Public Health,Kaohsiung Medical College, Kaohsiung, Taiwan;5Schoolof Occupational Safety and Health, China

Medical College, Taichung, Taiwan; 6Departmentof Public Health, Tzu-Chi College ofMedicine and Humanities, Hua-lien, Taiwan;

71nstitute ofEpidemiology, National Taiwan University,Taipei, Taiwan;8DepartmentofEnvironmental Health Sciences, Harvard School

ofPublic Health, Boston, Massachusetts, USA

Thisstudycompared theprevalenceof asthmawithclimateand airpollutantdata todetermine

therelationshipbetweenasthmaprevalenceandthese factors.Weconductedanationwide survey ofrespiratoryillnessand symptomsinmiddle-school studentsin Taiwan.Lifetimeprevalences of physician-diagnosedasthmaand oftypical symptoms of asthma were compared to airmonitoring

stationdata for temperature, relativehumidity,sulfur dioxide, nitrogen oxides, ozone, carbon monoxide, and particulate matter withaerodynamic diameter. 10 jam

(PM1O).

A total of 331,686 nonsmoking childrenattended schools located within 2 km of 55 stations. Asthma prevalenceratesadjusted forage,historyofatopic eczema,and parental education wereassociated with nonsummer(June-August) temperature, winter January-March) humidity, and traffic-related airpollution,especiallycarbon monoxide and nitrogen oxides,for bothgirlsand boys.

Nonsummertemperature, winterhumidity,andtraffic-related airpollution, especially carbon monoxide andnitrogenoxides,were

positively

associated with theprevalenceof asthmain mid-dle-schoolstudentsinTaiwan. Keywork:airpollution, asthma, children,climate,environmental exposure.EnvironHealt Prpect 107:1001-1006(1999). [Online 17 November19991 http:/llepnetl.niehs.

nib.gov/docs/l999/107p1001-1006golahbstract.html

Inhumans, airpollutants are associated with

mortalityandmorbidity secondaryto respira-torydiseases.Inpopulationstudies, effectsof airpollution have been associatedwith asth-mamorbidity and exacerbation ofsymptoms.

Increased hospitalizations (1,2), emergency room anddinic visits (3,4), andmedication use (5) due toasthma attacks, aswell as

decreased peak flowmeasurements (6) in

asthmatics,havebeenassociatedwithair

pol-lution. However, the relationship between the prevalence ofasthma andair pollution

has yet to be proven. InTaipei,Taiwan, the increasein theprevalence of childhood

asth-ma (from 1.3% in 1974 to 5.1% in 1985)

amongchildren 7-15 years ofagehas been

attributed todeterioration in air

quality

(7).

Ontheother

hand,

numerousstudies inthe UnitedStatesand inEurope have shownno

associationbetweenair

pollution

and reports

of asthma

(8,9).

Inclinicalexposuresof asth-matics, short exposureto airpollution pro-ducesincreasedairwayreactivity. Thresholds in sulfur dioxide-induced bronchoconstric-tion were lower in asthmatics (10), and

ozone-inducedlungfunction

change

and

res-piratorytract injury and inflammation were

moreprominentinasthmatics(11).

Many factors contributed to the preva-lenceand/or attacks ofasthma, including personal factors (smoking

habits,

genetics,

age, sex, nutritional status,

physiologic

sta-tus, coexisting lung

disease,

lifestyle, allergy

status, family history, and occupation) and environmental stimuli (outdoor and indoor

pollution, aeroallergens, climate) (12). The

relative importanceof outdoor airpollution

exposure tothe incidence and prevalence of

asthma ascompared to other intrinsic and

environmental factorsis notunderstood.

In this investigation, we compared

asthmaprevalence data from a nationwide

survey of middle-school students with air

pollutant and climatic data from 55 moni-toring stationsof the TaiwanEnvironmental

Protection Administration (EPA; Taipei,

Taiwan) to assessthe effectsofairpollutants

onasthma.

Subjects

and Methods

Respiratory healthquestionnaire. Between

October1995and May1996, weconducted a nationwide survey for respiratory diseases and symptoms in middle-school students.

ThestudyprotocolwasapprovedbytheEPA Respiratory Health Screening Steering Committeeand theInstitution ReviewBoard atNationalChengKung University Medical

College (Tainan, Taiwan), and

complied

with theprinciples outlinedin the Helsinki declaration (13). Chineseversions oftwo

questionnaires were used: the parent core

questionnaire, whichwastaken home

by

the

students, and the standard International

Studyof Asthma andAllergiesin

Childhood,

Chinese version, avideo questionnaire (14)

administered to students in schools.

Classroom incentives but not individual

incentiveswere used to encourage participa-tion. The overall response rate was 89%, with arangeof 87-93% for the individual schools.

Definition of diseases and symptoms. Two indicators of asthma were considered. Physician-diagnosed asthma was defined by

parentalreportsof thechildeverbeing diag-nosedbya physicianas having asthma. The video questionnaire determined asthmatic symptoms including dyspnea, wheezing,

exercise-induced wheezing, wheezing, ordry cough at night unassociated with a cold.

Questionnaire-determined asthmawas

definedbythe reportof dyspnea and noctur-nal dyspnea associated with wheezing (from thevideo questionnaire), the report of attacks ofdyspnea with wheezing(from theparental

questionnaire), or physician-diagnosed asth-ma (reported by a parent). Atopic eczema was defined as the presence ofitching skin eruptionatcubital, posteriorpopliteal, neck,

periauride, and eyebrowareas for6 months or longer, and a diagnosis ofatopic eczema

by a physician. Information on lifetime

prevalences ofasthmaandatopic eczema was obtained using thesedefinitions.

Air pollutant monitoring data.

Completemonitoringdatafor theair

pollu-tants

S02,

nitrogenoxides

(NOX),

03,carbon

monoxide, and particles with aerodynamic

diameter< 10 pm

(PM1O)

were available

from 66 EPA monitoringstations in 1994

and later years. Concentrations ofeach pol-lutant were measured continuously and

reported hourly-CO by nondispersive

Addresscorrespondence to R-S.Lin, Instituteof Epidemiology, National Taiwan University, 1

JenAiRoad, Sec 1, Taipei, Taiwan.Telephone:

8862 2391 4424.Fax: 88622341 8997. E-mail:

linrs@episerv.cph.ntu.edu.tw

We thank the collaboratorsin the participating

centersand all of the parents,children, teachers,

and other schoolstaffwhoparticipatedinthe

sur-veys.Wealso thank thefield workers whosupported

data collection.

This study was partially funded by the EnvironmentalProtectionAdministration, Taiwan,

andpartiallysupported byNSCgrant

87-2621-P-006-013.

Received12May 1999;accepted30July1999.

(2)

infraredabsorption, NO by chemilumines-cence, 03 by ultraviolet absorption, SO2 by ultraviolet fluorescence, and

PMIO

by beta-gauge. Temperature and relative humidity were measured daily at each station. The study population was limited to children attending schools located within 2km of 55 of these monitoringstations(Figure 1).

Site-specific average annualairpollution, temperature, andhumiditywerecalculatedas the mean of the 1994 monthly averages. Temperature and relative humidity were highlycorrelated across the sites. Principal componentfactor analysis withvarimax rota-tion (15) was used to produce independent indicators ofthe site-specific climate. There werealso strong between-site correlations of thefive monitoredair pollutantsSO, NON, 03, GO, and

PM.10.

Principal component factor analysis withvarimax rotation wasalso usedtodefinesource-specific indicators ofair pollutionexposure.

Statisticalanalysis forhealth and expo-sureassociations. Asthma is associated with individual factors suchasage, sex, atopy,and socioeconomic status. We used two-stage methods toanalyzetheprevalenceofasthma ineachgender.Intheanalysisof both

physi-cian-diagnosed and questionnaire-deter-mined asthma rates, logistic regression was used to estimate theadjustedillness frequen-cy in each of the 55 catchment areas, con-trolling for age, historyofatopic eczema, and parental education. The sex-specific prevalence rate of asthma among students wascalculated foreach catchment area. Self-reported active smokers were excluded. In the second step, these site-specific adjusted asthma prevalence rates were regressed against thearea-specific temperature,relative

humidity, and air pollution factors using weights proportional to the inverse variance (1/standard error2) ofthe adjusted preva-lencerates. The adjusted prevalence rates were plotted against the scores ofair pollu-tantprincipalcomponentsafter adjustingfor thetemperature andhumidity variables.

Results

In September 1995 there were 1,139,452 students enrolled in 800 middle schools in

24countiesand cities inTaiwan. A total of

1,018,031

(89.3%)

students and their

par-entsresponded satisfactorilytothe

question-naire.The

prevalence

ofasthmarangedfrom 4.6% inYunlin County,central Taiwan, to

12.0% in Taipei City, northern Taiwan. Among these students, 161,744 boys and

170,942 girls were nonsmokers and were

enrolled in a school within 2 km ofan air

pollutantmonitoringstation.Table 1 shows the characteristics ofstudysubjects bysex.

Figure2summarizesthe 1994annual mean

concentration of criteria air pollutants, the temperature, andthe relative humidity in

the 55monitoringstations.Table2

summa-rizesthesite-specificairpollutionand mete-orologicannual means atthesesites.

Two factors were identified from the

principal componentanalysisofthe site-spe-cific temperature: summer and nonsummer

monthtemperatures (Table 3).Threefactors

werefoundfor relativehumidity: spring

dry-ness, winter humidity, and the second-half yearhumidity (Table 4). Two factors were

identified for thesite-specific air pollutants (Table 5). The first site-specific factor was positivelyassociated with CO and

NOX

and

negatively associated with

03,

suggesting

motor vehicle emissions; the second was

...:

..

X...

>

Figure1.The 55 airpollution monitoring stations inthis study and their 2-km catchment areas in

Taiwan,1994.

Table 1.Prevalence rate of asthma by characteristics of the study population in Taiwan as of 1 January

1996.

Boys Girls

Physician- Questionnaire- Physician-

Questionnaire-diagnosed determined diagnosed determined

Number1%) asthmal%l asthma(%) Numberl%l asthmal%l asthma(%l

Age(years)

<13 36,202(22.7) 7.1 12.5 37,297(22.3) 4.3 8.3

13 54,661(343) 65 111 56,816(33.9) 42 80

14 53,618(337) 59 101 57,240(342) 37 71

>15 14,650(92) 54 92 16,078(96) 38 73 Education level(years)'

<6 29,540(186) 42 84 32,470(194) 26 63 6-8 39,781(25.0) 4.7 9.2 41,177(24.6) 3.1 6.5 >9 89,810(56.4) 78 125 93,784(560) 49 87 Atopic eczema No 157,418 (98.9) 62 107 165,739(99.0) 39 7.5 Yes 1,713(1.1) 21.3 30.1 1,692(1.0) 17.1 23.8

Totalboys,n=159,131; total girls, n=167,431.

aParents.

t.*1

..7 .., . Iv .. . -0 >;X aaC :th ( z Month

g.W

lw a i A I3

I

1Wr 90 80 70 60. 50 40 ,.3 S 2 2. W CL 0 o30 CJa C -~ LL < -5 -cc4 M/ 0 z month _C ( CL n u. ; E -s -n 4c eC

F.:A.

.:: 1

:.'...

Figure2. Summaryofarea-specific annual mean air pollutant concentrations:55monitoring stations in Taiwan, 1994.

(A)

Traffic-related air pollutants. (B) Nontraffic-relatedairpollutants.(C)Temperatureand relativehumidity. Error bars indicate standard error.

Volume 07 Number 2 December 999 * EnvironmentalHealth Perspectives

(3)

Children's Health * Air pollutants and asthma prevalence in children

highly associated with S02 and

PM1O,

sug-gesting emissions frompower plants,

indus-try, and domestic fossil fuel combustion, as

recentlyreviewed in Taiwan (16).

Physician-diagnosed (Table 6) and ques-tionnaire-determined (Table 7) asthma was regressed against the two temperature factors, three relative humidityfactors, and two air

pollutantfactors. Physician-diagnosed asthma was moreprevalent in communities with

higher temperature in nonsummer months

and higher traffic-related air pollution for bothgirlsandboys (Table 6).

Questionnaire-determined asthma was more prevalent in communitieswithhighertemperature in non-summer months, higher humidity in winter

months, and higher traffic-related air pollu-tionfor both girls and boys (Table7).

Adjustedsite-specific asthma prevalence

wasplottedagainstthetraffic-relatedair pol-lution factor scores (Figures 3 and 4). No outlier effects were apparent, and the regres-sionlineappeared linear.

The effect of each pollutant on the

prevalence rate of physician-reported and

questionnaire-determined asthma was

assessed separately and expressed as the dif-ferenceinprevalencerateacrossinterquartile

range for each air pollutant (Table 8). Positive

statistically

significant associations

were found for CO and

NOX;

negative or veryweak associations were found for 03,

SO2, and PM

O.

Although boys had higher

lifetimeprevalenceof asthma than girls in all levels ofair pollution, there were no

statisti-callysignificant differences in effect esti-matesforboys versus girls, indicating similar effects of air pollutants on asthma prevalence inboth sexes.

Discussion

This study is based on a nationwide survey of asthmalinked to a local air pollution mea-surement.Theprevalence of physician-diag-nosed andquestionnaire-determined asthma ofmiddle-school students from 55 locations was associated with temperature, humidity, and trafflc-related airpollutants, especially

COand NO.

Theclimatic factors, especially the non-summertemperature andwinterhumidity,

areassociated with the lifetime cumulative

incidence ofasthma. This is compatible with

findings inNew Zealand, where an increase of 1°C in annual average temperature is asso-ciated with a 1% increase of long-term asth-maprevalence, but not an acute exacerbation

ofasthma (17). Exposuretohouse dust mite

allergenisthe most importantfactorin asth-ma in Taiwan (18). Increased temperature

Table 2. Mean and distribution of 1994 annual airpollutionandmeteorologydata from55monitoring

sta-tions in Taiwan.

25th 75th

Mean±SD Minimum percentile Median percentile Maximum

CO(ppb) 853±277 381 675 843 1,001 1,610 NOx(ppb) 35.1±13.4 10.2 25.6 34.0 42.9 72.4 S02(ppb) 7.57±4.15 0.88 5.01 7.22 8.77 21.2 PM10 (pg/Mr3) 69.2±17.8 40.1 54.0 65.9 81.7 116.2 03(ppb) 21.3±4.5 12.4 18.7 21.5 23.4 34.1 Temperature(°C) 22.9±1.1 19.6 22.3 22.8 23.6 25.1 Relativehumidity 76.2±3.7% 64.8% 74.8% 76.6% 78.6% 86.2%

Abbreviations:PM10,particulatematter<10pminaerodynamicdiameter;SD,standard deviation.

Table 3. Factorloading of themonthlyaverage temperatureinTaiwan. Factorl Factor2 Eigenvaluesa 9.27(77.3%) 1.67(14.0%) January 0.927 0.303 February 0.929 0.283 March 0.966 0.188 April 0.896 0.235 May 0.891 0.309 June 0.398 0.856 July 0.338 0.900 August 0.082 0.901 September 0.523 0.804 October 0.747 0.587 November 0.880 0.434 December 0.867 0.413

Factordescription Nonsummer Summer

warmth warmth

Two factorshaveeigenvalues>1 andaccountfor91.2% of variance. Values in italicsarethose rotated factor

scoreswith absolute value>0.5. Percentvarianceexplained.

Table4.Factorloading of themonthlyaverage of relativehumidityinTaiwan.

Factor1 Factor2 Factor3

Eigenvaluesa 5.62(46.8%) 2.14(17.8%) 1.35(11.2%) January 0.162 -0.016 0.903 February 0.160 -0.242 0.902 March 0.174 -0.566 0.704 April 0.122 -0.809 0.188 May 0.063 -0.909 0.139 June 0.209 -0.737 0.077 July 0.745 -0.331 0.200 August 0.746 -0.366 0.076 September 0.902 -0.239 0.095 October 0.875 -0.122 0.134 November 0.804 -0.048 0.206 December 0.733 0.110 0.046

Factor Summer and Spring Winter

description fallhumidity dryness humidity

Threefactors haveeigenvalues>1 andaccountfor75.9% of variance. Valuesinitalicsarethose rotatedfactor

scoreswith absolute value>0.5.

&Percent varianceexplained.

(upto30°C) and increased relative humidity

favorthedevelopment ofmites (19). This is especially true during the colder seasons.

Although in areas with lower humidity indoor dampness is probably more important than outdoor humidity in the domestic

developmentof mites

(20),

the high outdoor

humidity in Taiwan (monthly average

68-80%; Figure 2C) could have been an importantdeterminantof the indoor humid-ity. The results of this survey suggest that exposure to dust mites or other humidity

sensitive allergenswas elevated in the chil-dren from warm andhumid areas in Taiwan.

Because of the close correlation among the airpollutants, it is impossible to separate the effects of individual pollutants. Therefore, we used factor analysis to group the patterns of pollutants into twodasses of pollutants: traffic-related and stationary fossil fuel-related (Table 4). We found a strong correlation between traffic-relatedpollutants

and lifetime prevalence of asthma in both boys andgirls (Figures 3 and4). Whenthe effect of each pollutant on the asthma preva-lence rates was examined (Table 8), signifi-cant association wasfoundforCOand

NOX.

No consistent relationship was seen among asthmaprevalence and 03, SO2, and

PM10.

Whether air pollution caused increased

prevalence of asthma has been a subject of

longdebate.High levels ofsulfurdioxideand black smoke in East Germany were associat-ed with lowerprevalence of asthma as

com-pared to West Germany (21). However, these data couldnotexcludearole formotor vehicle pollutants in increasing the occur-renceof asthma. Children livingnear roads are morelikely to have recurrent wheezing

anddyspneaaswellasreducedpeak expirato-ryflow rate(22).Japanese womenliving near

roadways are more likelyto have chronic wheezing adjusted byage, smokingstatus, years ofresidence, occupation, and type of homeheating (23).InAustria,lifetime preva-lence of asthmawasassociated withlong-term Table5.Factor loadingof themonthly average levels of criteria airpollutantsinTaiwan.

Factor1 Factor2

Eigenvaluesa 2.92(58.3%) 1.31(26.2%)

Average CO level 0.927 0.127

AverageNOXlevel 0.911 0.278

Average 0 level -0.921 0.038

Average

S62

level 0.268 0.827

AveragePM10level -0.037 0.901

Factordescription Traffic-related Stationary

fossil fuel

combustion-related

PM,0,

particulatematter<10 pm inaerodynamic

diame-ter.Two factors haveeigenvalues>1 andaccountfor 84.5%ofvariance.Values in italicsarethoserotated factorscoreswithabsolute value>0.5.

&Percentvarianceexplained.

(4)

Children's Health * Guo et al.

traffic nitrogen dioxide exposure in a dose-related fashion (24). Ina Canadian case-control study to compare newly diagnosed

asthmatic children andcontrols, NO2 expo-sureof> 15ppbby personalbadgefor 24 hr wasassociated with an odds ratio of10after adjusting for other riskfactors, althoughthe

NOx

exposureincluded both outdoor and indoorsources (25). Ourstudy findings are compatible with thehypothesisthat exposure to traffic-related pollutants might have caused changes in the susceptibility of chil-dren to allergens and therefore may have

contributedtothedevelopmentof asthma.

Whether this was directly relatedto CO or NOx from automobile exhaust or was

actuallycausedby other traffic-related

pollu-tants notmeasured by the monitoring station could not be determinedin this study. It is

unlikelythatCO iscausally relatedtoasthma prevalence. CO affects cardiovascular func-tion,althoughithas notbeen showntobea respiratory irritant.

NOX

are acuterespiratory irritants in animal andcontrolled human exposurestudies. However, inepidemiologic

studies of indoor NO2 exposures from gas

stoves, there is not strong or consistent evi-denceof associations with asthma prevalence.

High traffic density is inversely correlat-ed withconcentrations of03 (22), which is formed at some distance from emission sources and scavenged in city centers

by

nitrogen monoxide from vehicle exhaust. In ourfactoranalysis, 03 had a negative associ-ation with traffic-related pollutants (Table 5). From the individual pollutant regression analysis, 03 had either negative or no associ-ation with lifetime prevalence of asthma (Table 8). This is compatible with the hypothesis that the direct emissions of motor vehicles, which scavenge 0 and therefore are negatively correlatedwith 03, are more important determinants of asthma preva-lence than the secondary pollutants, such as

03,

that are formed downwind.

Other studies have suggested increased asthmaprevalenceassociated with traffic emis-sions. Wjst and colleagues (26) found that

school-specificprevalences of recurrent wheez-ing and dyspnea were positively associated with traffic volume in the school district. Edwards et al. (27) reported that hospital

admission ofchildren younger than 5 years ofage for asthma increased with traffic vol-umeand decreased with distance from the nearest main road. Brunekreefetal. (28)

foundthat

lung

function of children attend-ing schools within 300 m ofamajor road decreased in association with truck-traffic

volume,butnotwith automobiletraffic. CO and

NOX

areimportantconstituents of motor-vehicle emissions. Other major

components of motor-vehicle exhausts not measuredinthisstudyinclude fine and ultra-fineparticles (includingvariousheavymetals)

andawiderange oforganiccompounds.The

PMIO

measurements wereonly wealdy corre-lated across sites withtraffic-relatedpollution,

andlikelyreflect emissionfrom sources other thanmotorvehicles. Fineparticle concentra-tions were notassociated with asthma preva-lence in children in the 24 citiesstudy, but this study specifically excluded communities with substantial traffic-related pollution (9).

Therealso are fewepidemiologic data on asthmaassociations with organiccompounds. However, Ware et al. (29) reported that school-specific asthma prevalence in Kanawha

Table 6.Relationship between adjusted parent-reported physician-diagnosed asthma prevalence1%) and environmental factors inmiddle-school students.

Boys(R,=0.57) Girls(/Q=0.50)

Estimate 95%confidence interval Estimate 95% confidence interval

Intercept 5.8# (5.5,6.2) >3.5' (3.3,3.8)

Temperature

Nonsummer 0.90# (0.41,1.4) 0.59** (0.20,0.98)

Summer 0.59* (0.12,1.1) 0.41* (0.059,0.76)

Humidity

Summer and fall 0.21 (-0.055,0.47) 0.20 (-0.0024,0.42)

Spring -0.29 (-0.61, 0.042) -0.23 (-0.49, 0.037)

Winter 0.37* (0.0078,0.73) 0.15 (-0.14,0.43)

Airpollution

Traffic-related 1.1' (0.67, 1.6) 0.69# (0.32,1.06)

Stationaryfossil fuel -0.58** (1.00,-0.17) -0.032 (-0.68,0.037) combustion-related

Resultswereobtainedby multiple regression using prevalence of physician-diagnosed asthmaas thedependent variable and factorscoresof temperature, relative humidity, andairpollutantsasthe independent variables.

*p<0.05.**p<0.01.#p<0.001.

Table7. Relationship between adjusted questionnaire-determined asthma prevalence(%) and

environ-mentalfactorsinmiddle-school students.

Boys (R2=0.51) Girls(fQ=0.41)

Estimate 95% confidence interval Estimate 95%confidence interval

Intercept 10.3# (9.8,10.7) 7.1# (6.7, 7.5)

Temperature

Nonsummer 1.3# (0.66, 1.9) l.10# (0.54, 1.7)

Summer 0.66* (0.05, 1.27) 0.27* (-0.25, 0.78)

Humidity

Summerand fall 0.16 (-0.18,0.50) 0.27 (-0.039, 0.58)

Spring -0.38 (-0.80,0.05) -0.20 (-0.57, 0.18)

Winter 0.74** (0.27,1.21) 0.47* (0.05, 0.89)

Airpollution

Traffic-related 0.99** (0.37,1.60) 0.85** (0.33, 1.37)

Stationaryfossil fuel -0.13 (-0.67,0.41) -0.23 (-0.74, 0.28) combustion-related

Results wereobtainedbymultipleregression using prevalenceofquestionnaire-determined asthmaas thedependent

variableandfactor scores of temperature, relativehumidity,andairpollutantsas theindependent variables. *p<0.05.**p<0.01.#p<0.001. 14

SrJB-S":

;~~~~~~~~~~~~~~~~~~~~~~~.A.;.:.;....;.:.

E12 ...::.,:;,:-CD 8 ...;;,. f. e [24 ....

.4^v...~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~....

. .... a. {.. . -f ; ,e -2 -1 0 1 2

Score of traffic-related air pollunt Figure 3. Association ofphysician-diagnosed asthma prevalencewithtraffic-relatedair

pollu-tantsadjusted fortemperature and relative humidity in the55monitoringstations.Means and

standarderrors areshown.

ae 4 ... .

.0

.

L..

.if.4z;. ... ..

-2 -1 0 1 2

Score oftf icreledarpetl

Figure4.Association of questionnaire-determined

asthma prevalencewithtraffic-related air

pollu-tants adjustedfortemperature and relative humidityinthe 55 monitoring stations. Means and

standard errors areshown.

Volume 107, Number 12, December 1999 * Environmental Health Perspectives

(5)

Children's Health * Airpollutants and asthma prevalence in children

County, West Virginia, increased with petro-leum air pollution concentrations. In this studyofasthma prevalence in Taiwan, CO and

NOX

may have served as indicators of motor vehicle emissions rather than as direct measurements of the causal agent.

We found no association between life-timeasthma prevalence and nontraffic-relat-ed air pollutants, namely, SO2 and

PMIO.

Thisis compatible with results from the Six Cities Study of Air Pollution and Health (30), which showed no correlation among

PM15,

PM25, and SO2 and doctor-diag-nosedasthma.

Questionnaires have been used to assess the prevalenceofasthmain previous studies

(31,32). Asthma is usually defined as current asthma (i.e., wheezing within the past 12 months). We used lifetime prevalence of asth-ma as oneofour outcomevariables to exam-ine theeffects of air pollution to the develop-mentof asthma. Underestimation of the true asthmaprevalenceislikelyif parent reportsof physician-diagnosed asthma are used. We

compensated for this underestimation by adding self- and parent-reported wheezing, dyspnea, and nocturnal dyspnea, whichwe called questionnaire-determined asthma. In the 55 geographic areas studied, question-naire-determined asthmahadastrong correla-tion withphysician-diagnosed asthma, with P2 0.79 for boys and 0.81 forgirls.

There are advantages in the exposure

informationinthisstudy.InTaiwan, mostof

the elementary and middle school students live close to their schools. Monitoringstations located near the schools arealso likelytobe

near the students' homes, thus providing goodsurrogates for bothschool and home

exposure. Heating andairconditioning are rare inTaiwaneseclassrooms. Air condition-ing has become morepopular for residential homesin recentyears;heatingisuncommon. Coalstoves were usedin < 2%of homes in 1994, probably more in rural thanin urban

areas (33). Notadjusting forcoal stove expo-sure could have reduced the magnitude of association. The exposure information obtained from air pollution monitoring sta-tions was limitedto the criteria air pollutants in 1994. Airpollution measurements prior to 1994 were notavailable. Moving from one catchment areato another could have led to misclassification of exposure. However, the errorsinexposure assessment are likely to be random, which would reduce the magnitude

ofassociationbut would not introduce a posi-tivebiasinthe associations.

Thelack of personal exposure data pro-hibited analysis comparing individual expo-sure and outcomes. Therefore, the adjusted prevalence rateofasthma for each catchment area wasused to determine theeffects of air

pollutantsonthe respiratory system. Because asthma was potentially associated with age, atopy, and socioeconomic status, these fac-tors werecontrolledbythefirst-stage regres-sion. Maternal smoking during pregnancy was associated with increased cord blood immunoglobulinE(34) andthereforemight be apredictive factorof asthma. However,<

5%ofTaiwanese womensmoked (35), and

obtaining maternal smoking history was considered somewhat sensitive. Therefore,

maternal smoking history during pregnancy was notincludedinthe questionnaire. There is no reason to believe that traffic-related

pollutants were associated with maternal

smoking. Smoking prevalence in women is lowerinurban thaninrural areas;therefore,

if there is an adverse effect ofmaternal

smoking during pregnancy on childhood

asthma, it should have reduced the associa-tion between traffic-related pollutants and

the prevalence of asthma. Secondary smok-ing can be a risk factor for asthma (36).

Having an asthmatic child at home is a strong motivation for reductionorcessation

ofsmoking. Because the causal relationship

between secondary smokingand asthma in

Table8.Effectof each pollutantonthe prevalence rateof physician-diagnosed and

questionnaire-deter-minedasthma.

Physician-diagnosedasthma Questionnaire-determinedasthma Estimate 95% confidence Estimate 95%confidence

(%) interval (%) interval Boys CO(ppb) 1.17 (0.63-1.72) 1.10 (0.45-1.75)

NO,

(ppb) 0.88 (0.23-1.52) 0.99 (0.28-1.70) 03(ppb) -0.89 (-1.51--0.27) -0.68 (-1.40-0.05) S02(ppb) -0.15 (-0.55-0.25) 0.11 (-0.34-0.56)

PM,o

(pg/mr3) -0.96 (-1.82 - -0.09) -0.29 (-1.32-0.75) Girls CO(ppb) 0.84 (0.45-1.22) 1.00 (0.44-1.56) NOX(ppb) 0.50 (0.03-0.97) 0.77 (0.13-1.42) 03(ppb) -0.43 (-0.89 -0.03) -0.62 (-1.25 -0.007) SO2(ppb) 0.027 (-0.28-0.33) 0.12 (-0.30-0.53) PM1o(pg/M3) -0.52 (-1.18 -0.13) -0.41 (-1.33-0.52)

PM10,particulatematter<10 pm in aerodynamicdiameter. Effect isexpressedasthedifferencein prevalencerate

acrossinterquartilerange.

children could not be determined for this cross-sectional design, we did not include passivesmoking in our

adjusting

factors.

The studied population was a sample of the total population of middle-school chil-dren in Taiwan. Because information on air pollution is a prerequisite of this investigation, only the children in areas around air monitor-ing stations were chosen. The previous selec-tionof sites by the EPA for establishing moni-toring stations was nonrandom and probably

favored places with expected high air pol-lution concentrations. As compared to the total number of middle-school students in Taiwan, selected subjects were similar in sex (male 50.4%) and age (average 13.8 years). However, the parents of these students had moreeducation, smoked less, and complained more about air pollution problems.

Inconclusion, parental reports of physi-cian-diagnosed asthma and questionnaire-determined asthma are both associated with natural environmental factors such as tem-perature and humidity, probably mediated by exposure to common allergens such as dust mites. Asthma prevalence rates were highly correlated with traffic-related air pol-lutants (CO and

NOX)

but not other pollu-tants

(PM10,

03,andSO2). Whether this is related to urbanlifestyle, to exposure to CO and

NOX,

or to othertraffic-related pollu-tants warrantsfurther investigation.

REFERENCESANDNOTES

1. WaltersS, Phupinyokul M, Ayres J. Hospital admission ratesfor asthma and respiratory disease in the West Midlands: their relationship to air pollution levels. Thorax 50:948-954(1995).

2. SheppardL, Levy D, Norris G, Larson TV, Koenig JQ. Effects of ambient air pollution on nonelderly asthma hospital admissions inSeattle,Washington, 1987-1994. Epidemiology 10:23-30(1999).

3. CastellsagueJ, Sunyer J,Saez M, Anto JM. Short-term association between airpollution and emergencyroom

visits for asthma in Barcelona. Thorax 50:1051-1056(1995).

4. SunyerJ,Spix C, Quenel P,Ponce-de-LeonA,PonkaA,

BarumandzadehT, TouloumiG,BacharovaL,Wojtyniak

B, Vonk J,etal. Urban airpollution and emergency admissionsfor asthma in fourEuropean cities: the APHEAProject. Thorax52:760-765(1997).

5. GielenMH,vander ZeeSC,vanWijnen JH,vanSteen

CJ,Brunekreef B. Acute effects ofsummerairpollution

onrespiratory health of asthmatic children. Am JRespir

CritCare Med 55:2105-2108(1997).

6. Segala C,FaurouxB,JustJ,PascualL,GrimfeldA,

Neukirch F. Short-term effect of winter airpollutionon

respiratory health of asthmatic children in Paris. Eur Respir J 11:677-685(1998).

7. HsiehKH, Shen JJ. Prevalence of childhood asthma in Taipei, Taipei, Taiwan and other Asia Pacific countries. J Asthma 25:73-82(1988).

8. DockeryDW, Speizer FE,StramDO,WareJH,Spengler JD,

FerrisBG Jr. Effects of inhalableparticlesonrespiratory healthof children.Am RevRespir Dis 139:587-594(1989).

9. DockeryDW, Cunningham J, DamokoshAl,NeasLM, Spengler JD,KoutrakisP,WareJH,RaizenneM,Speizer

FE. Healtheffects of acid aerosolsonNorth American children:respiratorysymptoms. Environ HealthPerspect

104:500-505(1996).

10. PetersA, DockeryDW,HeinrichJ,WichmannHE.

Short-termeffectsofparticulate airpollutiononrespiratory

morbidityin asthmatic children. Eur Respir J 10:872-879 (1997).

(6)

11. Scannell C, Chen L, Aris RM,Tager I, Chistian D, FerrandoR, Welch B,Kelly T, Balmes JR. Greater ozone-inducedinflammatory responses in subjects with asth-ma.AmJ Respir CritCare Med 154:24-29(1996).

12. MartinBW,Ackermann-Liebrich U, Leuenberger P,Kunzli N,Stutz EZ, Keller R,Zellweger JP, Wuthrich B, Monn C, BlaserK, et al.SAPALDIA methods and participation in the cross-sectional partof the Swissstudy on air pollution and lungdiseases in adult.Soz Praventivmed 42:67-84(1997).

13. 41stWorld Medical Assembly. Declaration ofHelsinki: recommendations guiding physicians in biomedical research involving humansubjects. Bull Pan Am Health Org 24:606409(1990).

14. PearceN, Weiland SK, Keil U, Langridge P, AndersonHR, Strachan D, Bauman A.Self-reportedprevalence of asth-masymptoms in children in Australia, England,Germany and New Zealand:aninternationalcomparisonusing the ISAAC protocol. Eur Respir J 6:1455-1461(1993).

15. Kaiser HF.The varimax criterion for analytical rotation in factoranalysis. Psychometrika 23:187-200(1958). 16. KoYC. Air pollution and its health effects on residents in

Taiwanese communities[inChinese with English

abstract].Kaohsiung J Med Sci 12:657-669(1996).

17. Hales S, LewisS, Slater T,Crane J, Pearce N. Prevalence of adult asthma symptoms in relationtoclimate in New Zealand. Environ Health Perspect 106:607-610(1998). 18. Hsieh KH. A study of intracutaneous skin tests and

radioallergosorbent tests on 1,000asthmatic children in Taiwan. AsianPac JAllergyImmunol2:56-60(1984).

19. Arlian L, Dippold J. Development andfecundity of Dermatophagoides farinae(Acari: Pyroglyphidae).J MedEntomol 33:257-260(1996).

20. MunirAK,Bjorksten B, Einarsson R, Ekstrand-Tobin A, Moller C, Warner A,KjelimanNI. Mite allergens in rela-tion tohomeconditions andsensitization of asthmatic children from three climaticregions. Allergy 50:55-64

(1995).

21. vonMutius E, MartinezFD, FritzschC, Nicolai T, Roell G, Thiemann HH. Prevalence of asthmaand atopy in two areasof Westand EastGermany.Am J RespirCrit Care Med 149:358-364(1994).

22. WjstM, ReitmeirP, DoldS,WulffA, Nicolai T, von

Loeffelholz-Colberg E, vonMutius E. Road traffic and adverse effects on respiratory health in Children. Br Med J 307:596-600(1993).

23. Nitta H,Sato T, NakaiS, Maeda K,AokiS, Ono M. Respiratory health associated with exposure to automo-bileexhaust. I: Results of cross-sectional studies in 1979, 1982, and 1983. Arch Environ Health 48:53-58(1993). 24. Studnicka M, Hacki E, Pischinger J, Fangmeyer C,

Haschke N, Kuhr J, Urbanek R, NeumannM, Frischer T. Traffic-related NO2 and the prevalence of asthma and respiratory symptoms in seven year olds. EurRespir J 10:2275-2278(1997).

25. Infante-RivardC. Childhood asthma and indoor environ-mental risk factors. AmJEpidemiol 137:834-844(1993).

26. Wjst M, Reitmeir P, Dold S,Wulff A, Nicolai T, von

Loeffelholz-ColbergEF, von Mutius E. Road traffic and adverse effectsonrespiratoryhealth inchildren. Br Med J307:596-600(1993).

27. Edwards J,WaltersS,Griffiths RK. Hospital admissions forasthma in preschool children:relationship to major roads inBirmingham, United Kingdom. Arch Environ Health 49:223-227(1994).

28. Brunekreef B, Janssen NA, de Hartog J, Harssema H, Knape M, van Viiet P. Airpollution from truck traffic and lung function in children living near motorways. Epidemiology 8:298-303(1997).

29. Ware JH,Spengler JD, Neas LM, Samet JM, Wagner

GR,CoultasD,Ozkaynak H, Schwab M. Respiratory and irritanthealtheffectsof ambient volatile organic com-pounds. The KanawhaCounty Health Study. Am J Epidemiol 137:1287-1301(1993).

30. DockeryDW,Speizer FE,StramDO,WareJH,SpenglerJO,

Ferris BG Jr.Effects of inhalable particles on respiratory health ofchildren. Am RevRespir Dis 139:587-594(1989).

31. Burr ML, Limb ES, Andrae S, Barry DM, Nagel F. Childhood asthma in four countries: a comparative study. lnt J Epidemiol 23:341-347(1994).

32. Worldwide variation inprevalence of symptoms of asth-ma, allergic rhinoconjunctivitis, and atopic eczema:

ISAAC.The InternationalStudy of Asthma and Allergies inChildhood (ISAAC) SteeringCommittee. Lancet 351:1225-1232(1998).

33. ChenP-C,LaiY-M,Wang J-O, Yang C-Y, Hwang J-S,Kuo H-W,Huang S-L, Chan C-C. Adverse effect of air pollu-tiononrespiratory health of primary school children in Taiwan.Environ HealthPerspect 106:331-335(1998).

34. MagnussonCG.Maternal smoking influences cord serum

IgEandlgDlevels and increases the risk for subsequent infantallergy. J AllergyClin Immunol 78:898-904(1986).

35. YenL, PanL, Yen H, Lee L. The smoking status in adults in Taiwan area:prevalence rates and risk factors.Chin J Public Health 13:371-380(1994).

36. KjellmanNI. Effect of parental smoking onIgElevels in children. Lancet 1:993-994(1981).

For

as

little

as

$3.09*

per year per user,

your

students can have

full Internet

access

__..

_

. .

to

the

Environmental

Health Information

.... _...

Service

(EHIS)!

The EHIS offers online, searchableaccess to:

.

Environmental

Health

Perspectives

* Environmental Health

Perspectives Suipplements

* National

Toxicology Program

S

:Technical

and

Toxicity Reports

* Reporton

Carcinogens

* ChemicalHealth and

Safety

..

~~Database

*Rodent Historical Control Database Formoreinformationon

orderingcall 1-800-315-3010.

*Priceis ascedoni MltinpleU.serIntui OctAccess-EducationAccounts including fullInternetaccess for250users and

print copiesof1lHi> 1Hi Soipp/oleoioie andNTP'reports.

數據

Table 1. Prevalence rate of asthma by characteristics of the study population in Taiwan as of 1 January 1996.
Table 3. Factor loading of the monthly average temperature in Taiwan. Factorl Factor 2 Eigenvaluesa 9.27 (77.3%) 1.67 (14.0%) January 0.927 0.303 February 0.929 0.283 March 0.966 0.188 April 0.896 0.235 May 0.891 0.309 June 0.398 0.856 July 0.338 0.900 Aug
Table 7. Relationship between adjusted questionnaire-determined asthma prevalence (%) and environ- environ-mental factors in middle-school students.

參考文獻

相關文件

Weak solution for problems with shock &amp; rarefaction waves Interface indicator H I takes value zero away from interfacs, yielding standard compressible Euler equations

Curriculum planning - conduct holistic curriculum review and planning across year levels to ensure progressive development of students’ speaking skills in content, organisation

Research has suggested that owning a pet is linked with a reduced risk of heart disease, fewer visits to the doctor, and a lower risk of asthma and allergies in young

On the other hand, lower prices in hairdressing services, outbound package tours and air tickets after the Lunar New Year, as well as continuous price reduction in winter clothing

Relevant topics include, but are not limited to: Document Representation and Content Analysis (e.g., text representation, document structure, linguistic analysis, non-English

In these lessons, students will evaluate the impacts of genetic engineering on our daily life, and analyze the moral issues raised in its development, especially those related

Teacher / HR Data Payroll School email system Exam papers Exam Grades /.

Classifying sensitive data (personal data, mailbox, exam papers etc.) Managing file storage, backup and cloud services, IT Assets (keys) Security in IT Procurement and