Rev. paul. pediatr. vol.34 número1

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www.rpped.com.br

REVISTA

PAULISTA

DE

PEDIATRIA

ORIGINAL

ARTICLE

Fine

particulate

matter

estimated

by

mathematical

model

and

hospitalizations

for

pneumonia

and

asthma

in

children

Ana

Cristina

Gobbo

César

a

_,

_Luiz

_Fernando

_Costa

_Nascimento

b,∗

,

Katia

Cristina

Cota

Mantovani

b

_,

_Luciana

_Cristina

_Pompeo

_Vieira

b

a_Instituto_Federal_de_Educac¸ão,_Ciência_e_Tecnologia_de_São_Paulo,_Braganc¸a_Paulista,_SP,_Brazil

b_Departamento_de_Energia,_Universidade_Estadual_Paulista_Júlio_de_Mesquita_Filho,_{Guaratinguetá,}_SP,_Brazil

Received3March2015;accepted16June2015 Availableonline28December2015

KEYWORDS Asthma; Pneumonia; Airpollutants; Particulatematter; Childhealth;

Mathematicalmodels

Abstract

Objective: Toestimatetheassociationbetweenexposuretofineparticulatematterwithan

aerodynamicdiameter<2.5microns(PM2.5)andhospitalizationsforpneumoniaandasthmain children.

Methods: Anecologicalstudyoftimeserieswasperformed,withdailyindicatorsof

hospital-izationforpneumoniaandasthmainchildrenupto10yearsofage,livinginTaubaté(SP)and estimatedconcentrationsofPM2.5,betweenAugust2011andJuly2012.Ageneralizedadditive modelofPoissonregressionwas usedtoestimatetherelativerisk,withlagzerouptofive daysafterexposure;thesinglepollutantmodelwasadjustedbytheapparenttemperature,as definedfromthetemperatureandrelativeairhumidity,seasonalityandweekday.

Results: Thevaluesoftherelativerisks forhospitalizationforpneumonia andasthmawere

significantforlag0(RR=1.051,95%CI;1.016to1.088);lag2(RR=1.066,95%CI:1.023to1.113); lag3(RR=1.053, 95%CI:1.015 to1.092);lag4(RR=1.043, 95%CI:1.004to 1.088)andlag5 (RR=1.061,95%CI:1.018to1.106).Theincreaseof5mcg/m3_in_PM

2.5contributestoincrease therelativeriskforhospitalizationfrom20.3to38.4percentagepoints;however,thereduction of5␮g/m3inPM2.5concentrationresultsin38fewerhospitaladmissions.

Conclusions: ExposuretoPM2.5wasassociatedwithhospitalizationsforpneumoniaandasthma

inchildrenyoungerthan10yearsofage,showingtheroleoffineparticulatematterinchild healthandprovidingsubsidiesfortheimplementationofpreventivemeasurestodecreasethese outcomes.

∗_{Corresponding}_author.

E-mail:luiz.nascimento@pq.cnpq.br(L.F.C.Nascimento).

http://dx.doi.org/10.1016/j.rppede.2015.12.005

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PALAVRAS-CHAVE Asma;

Pneumonia; Poluentesdoar; Materialparticulado; Saúdedacrianc¸a; Modelosmatemáticos

Materialparticuladofinoestimadopormodelomatemáticoeinternac¸õespor pneumoniaeasmaemcrianc¸as

Resumo

Objetivo: Estimar a associac¸ão entreexposic¸ão ao material particulado fino com diâmetro

aerodinâmicoinferiora2,5micra(PM2.5)easinternac¸õesporpneumoniaeasmaemcrianc¸as.

Métodos: Estudoecológicodesériestemporaiscomindicadoresdiáriosdeinternac¸ãopor

pneu-monia e asma,em crianas comaté 10 anos, residentesem Taubaté (SP), econcentrac¸ões estimadas dePM2.5,entreagosto de2011e julhode 2012. Modelo aditivogeneralizadode regressãodePoissonfoiusadoparaestimaroriscorelativo,comdefasagemdezeroatécinco diasapósaexposic¸ão;omodelounipoluentefoiajustadopelatemperaturaaparente,medida definidaapartirdatemperaturaeumidaderelativadoar,sazonalidadeediadasemana.

Resultados: Osvaloresdosriscosrelativosparainternac¸õesporpneumoniaeasmaforam

sig-nificativosparalag0(RR=1,051;IC95%1,016-1,088);lag2(RR=1,066;IC95%1,023-1,113);lag 3(RR=1,053;IC95%1,015-1,092);lag4(RR=1,043;IC95%1,004-1,088)enolag5(RR=1,061; IC95%1,018-1,106).Oincrementode5mcg/m3dePM2.5contribuiparaaumentonorisco rela-tivoparainternac¸õesentre20,3a38,4pontospercentuais;noentanto,adiminuic¸ãode5␮g/m3

naconcentrac¸ãodoPM2.5resultaemmenos38internac¸ões.

Conclusões: Aexposic¸ãoaoPM2.5esteveassociadaàsinternac¸õesporpneumoniaeasmaem

criançasmenoresde10anos,mostrouopapeldomaterialparticuladofinonasaúdedacriançae forneceusubsídiosparaimplantaçãodemedidaspreventivasparadiminuíremessesdesfechos. ©2015SociedadedePediatriadeSãoPaulo.PublicadoporElsevierEditoraLtda.Esteéumartigo OpenAccesssobalicençaCCBY(https://creativecommons.org/licenses/by/4.0/deed.pt).

Introduction

Air pollution has been associated with increased risk of death,chronicdiseasesandparticularlyrespiratorydiseases inchildren.1---4_This_finding_may_be_explained_by_the

respira-torysystemimmaturity,aslungdevelopmentisprogressive

andcontinuousuntiltheageof 10,5_as_well_as_due_to_the

increasedemissionofpollutantsintotheatmosphere.6,7

Astudycarriedoutin20citieslocatedintwodifferent

regionsofCalifornia(USA),suggestedthatthelevelof

expo-suretofineparticulatematter<2.5micronsofaerodynamic

diameter(PM2.5)inchildrenbetween1and9yearsis

asso-ciatedwithincreasednumberofhospitalizationscausedby

acuterespiratoryinfectionssuchaspneumoniaandasthma.8

Data from the Ministry of Health reported more than

570,000admissionsin2011relatedtochildrenupto10years

ofage,whichgeneratedcostsofmorethan400millionreais

inBrazil.InthestateofSãoPaulo,therewereapproximately

100,000hospitalizationsgeneratingcostsofabout85million

reais.9

Pneumoniaandasthmaaremultifactorialdiseases.The

riskfactorsmostcommonlyassociatedwiththeiroccurrence

are low birth weight, the presence of smokers at home,

lackofbreastfeedingandexposuretoairpollutants.4,7,10,11

Specificallyincasesofasthma,vehiculartraffic,particularly

heavyvehicles,seemstobeimportant.3

Among air pollutants, those generated by biomass

burning,aswellasbymobilesourcesinvolved with

hospi-talizationsforrespiratorydiseasesinchildren,wehighlight

theimportanceofPM10and,amongthismatter,thefraction

withPM2.5.Thisfraction,calledfineparticulatematter,has

adiameterrangingbetween0.1␮mand2.5␮m(PM2.5)and

represents between 60% and 70% of the total particulate

matter.12 _The_use_of_logistic_regression_identified_the

asso-ciationbetweenexposuretoPM2.5andtheincreasedriskof

hospitalizationforchildhoodbronchiolitis(OR=1.09;95%CI:

1.04---1.14)inastudycarriedoutinCalifornia.13

Fine particulate matter is directly emitted by the

combustionofcoal,oil,gasandwood.Itisalsosecondarily

formedfromgaseousprecursors.Itprimarilyconsistsof

sul-phates,nitrates,chloride,ammoniacompounds,elemental

andorganiccarbon,aswellasmetals.Itcanremaininthe

atmosphereforlongperiodsandtravellongdistancesand

reachthedeepestportionsoftherespiratorytract.14

The particulate pollutants with larger diameters are

retained in the upper airways, while those with smaller

diametersreachthealveoli.5 _In_the _lungs,_these_particles

are phagocytosed by alveolar macrophages and removed

through the action of cilia and the lymphatic system.15

However,thehighlevelsofoxidantsandpro-oxidants

con-tainedintheparticulatescan causethe formationoffree

radicals,trigger an inflammatoryresponsewithreleaseof

inflammatorymediatorsandcells andinducea subclinical

inflammationoftherespiratorysystem.16

Inthecase ofPM10,itsquantificationisusuallycarried

outthrough state environmental agenciesmonitoring

sta-tions;ontheotherhand,PM2.5hasfewmonitoringstations

inthestateofSãoPaulo(SP).However,studiesusing

esti-matedconcentrationsof someairpollutants,amongthem

PM2.5,providedbythemathematicalmodelChemical

Cou-pled Aerosol and Tracer Transport Modelto the Brazilian

Developmentson the Regional Atmospheric Modeling

Sys-tem(CCATT-BRAMS),havebeenusedtoevaluatetheeffects

of air pollutant exposure.17,18 _The _use _of _estimated _data

becomesan option, in casesof cities where thereare no

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The objectiveofthisstudywastoevaluatetheroleof

PM2.5,estimatedby amathematicalmodel,in

hospitaliza-tionsfor pneumoniaandasthmainchildrenupto10years

ofage,livinginthecityofTaubaté(SP),whichhasno

mon-itoringstationforthistypeofpollutant.

Method

Thiswasanecologicalstudyoftimeserieswithdaily indica-torsofhospitalizationforrespiratorydiseases(International ClassificationofDiseases,ICD10:J12.0---J18.9,J45.0,J45.1, J45.8,J45.9andJ46)inchildrenupto10yearsofageand residentsinTaubaté(SP),fromAugust 1,2011toJuly31, 2012. These data were obtained fromthe Department of InformationandInformaticsof theUnifiedHealthSystem9

(DATASUS),inadditiontothemeanvalueofeachadmission

forthesediseases.Wealsocalculatedtheestimateddaily

meansofcarbonmonoxide(COinppb),nitrogenoxides(NOx

in␮g/m3)andfineparticulatematter(PM2.5in␮g/m3),and

amaximumof8hfortheozone(O3in␮g/m3)obtainedfrom

theCCATT-BRAMSsystem.17

Thetemperatureandhumiditydatawereprovidedbythe

WeatherForecastandClimateStudyCenteroftheNational

InstituteofSpaceResearch(CentrodePrevisãodoTempoe

EstudosClimáticosdoInstitutoNacionaldePesquisas

Espa-ciais --- CPTEC-INPE) and, from these data, the apparent

temperaturewascalculated,whichisafunctionof

tempera-tureandhumidity.Theapparenttemperatureconsidersthe

physiologicalexperienceofcombinedexposureofhumidity

andtemperature,andallowsamoreeffectiveevaluationof

theresponseofthesevariablesontheindividual’shealth.20

Variables relatedtoapparent temperature, seasonality

andcalendareffects(dayoftheweek)wereincludedtofit

themodel.

Taubatéis located inVale doParaíba,120km fromthe

state capital, at coordinates 22◦₄₅′_S _and ₄₅◦₃₀′_W, _with_a

populationof300,000inhabitantsinaterritoryofjustover

625km2_._It_has_an_important_industrial_park_with_automotive

andsteel industries.21 _The _city _is _crossed_by _Via_Dutra, _a

highwaythatconnects thetwolargest citiesin Braziland

hasafleetofapproximately200,000automotivevehicles.21

Pearson’scorrelationcoefficienttestwasusedto

evalu-atethe possiblecorrelationsbetweenhospitalizationsand

theestimatedlevelsofPM2.5.Astheeffectsofexposureto

environmentalpollutantscanleadtohospitalizationonthe

samedayoronsubsequentdays,theeffectsonthe

respira-torysystemwereinvestigatedonthedayofadmission(lag

0),andalsoonthesubsequent5days(lags1---5).The

gener-alizedadditivemodelofPoissonregressionwasusedbecause

theoutcomeisadiscretequantitativevariable.The

hospi-talization risk results refer to exposure toPM2.5 adjusted

for apparent temperature, seasonality and weekday. The

Statisticav7programwasusedforthestatisticalanalysis.

Theestimatedeffectsaretherelativerisks(RRs)

corre-spondingtotheincrease of 5␮g/m3 ofPM2.5.To interpret

the results, the RRs were converted into of percentage

hospitalizationrisk increase(HRI). Weappliedthe

expres-sionHRI=[exp(ˇ*pol)−1]*100, where ˇis the coefficient

obtained from Poisson regression and pol is the

varia-tion, in ␮g/m3, tobe added in the concentration of the

analyzed pollutant.4 _This _increase _allows _calculating _the

population-attributablefraction,that is,howmany

hospi-talizationsoccurredasaresultofthisincrease.Thecostsof

hospitalizationduetothisincreaseinconcentrationsofthe

fineparticulatematterwerecalculated.The5%significance

levelwasusedinallanalyses.

ThisstudywasapprovedbytheResearchEthics

Commit-teeofUniversidadedeTaubaté(OpinionN.068/12).

Results

During the study period, there were 140 hospitalizations for pneumonia and asthma in children up to 10 years of age, living in Taubaté (SP). The mean number of daily admissionswas0.4±0.7,withaminimumof0anda maxi-mumof4.TheestimatedmeandailyconcentrationofPM2.5

was13.2±5.7␮g/m3 _and _the _minimum_and _maximum

val-ueswere, respectively,0.40---41.30␮g/m3_,_with_the_values

exceeding the limit of 25␮g/m3 _established _by _the _State

Decree N.59113/13,22 _on ₈ _days _of _the _assessed _period.

Themeandailyapparenttemperaturewas20.4±4.0◦_C._The

descriptiveanalysisoftheindependentvariables(pollutants

andapparenttemperature)isshowninTable1.

Table2showsthePearsoncorrelationbetweenthestudy

variables. The hospitalizations for pneumonia andasthma

werepositivelycorrelated(p<0.05)withthePM2.5,

season-ality and apparent temperature (p<0.01). The apparent

temperature waspositively correlated withthe PM2.5 and

seasonality(p<0.05).Thisjustifiestheuseofsuchmeasures

asadjustingvariablesinthemodel.

As for Poisson regression, the analysis with the

single-pollutant model (PM2.5) adjusted by the apparent

temperature, seasonality and weekday, Table 3 shows

the coefficientsand their respectivestandard errors.The

effectsofthepollutantonchildren’shealthwerequantified

by RR,which expressestheprobabilityof anindividualto

developadiseaserelatedtoexposuretoariskfactor.

The RRandtheir respectiveconfidence intervals (CIs),

which were significant, according to the exposure to

PM2.5 and hospitalization,refer tolag 0(RR=1.051; 95%CI

1.016---1.088); lag 2 (RR=1.066; 95%CI 1.023---1.113); lag

3 (RR=1.053; 95%CI 1.015---1.092); lag 4 (RR=1.043; 95%CI

1.004---1.088)andlag5(RR=1.061;95%CI1.018---1.106).The

RRsandcorresponding95%CIsforalllagsareshowninFig.1.

TheincreaseinRRswiththeincrementof5␮g/m3inPM2.5

concentrations imply in increases between 20.3 and 38.4

Table1 Descriptiveanalysisofairpollutantsandapparent temperature(◦_C)._Taubaté,_São_Paulo,_2011---2012.

Mean (standard deviation)

Minimum---maximum

Carbonmonoxide(ppb) 119.1(39.3) 33.3---281.3

Ozone(␮g/m3) 36.4(16.2) 10.5---98.0

Nitrogenoxides(␮g/m3) 2.1(1.7) 0.2---15.8

Particulatematter<2.5 micronsofaerodynamic diameter(␮g/m3)

15.4(3.8) 11.5---41.3

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Table2 Pearson’scorrelationmatrixbetweenthevariableshospitalizations,particulatematter<2.5micronsofaerodynamic diameter,apparenttemperature(◦_C),_seasonality_and_weekday._Taubaté,_São_Paulo,_2011---2012.

Variables Hospitalizations Particulatematter<2.5

micronsofaerodynamic diameter

Apparent temperature(◦_C)

Seasonality Weekday

Hospitalizations 1

Particulatematter<2.5 micronsofaerodynamic diameter

0.21b ₁

Apparenttemperature(◦_C) _0.11a _0.52b ₁

Seasonality 0.28b _0.34b _0.32b ₁

Weekday −0.05 0.054 −0.04 −0.01 1

a _Significant_correlation_for_p_<0.01. b _Significant_correlation_for_p_<0.05.

Table 3 Values of the coefficients and standard errors for the exposure to particulate matter <2.5 microns of aerodynamicdiameter,single-pollutantmodeladjustedfor apparenttemperature,seasonalityandweekday,according tolags(lag)0---5days.Taubaté,SãoPaulo,2011---2012.

Lag(days) Coefficients(standarderror)

Lag0 0.04982(0.01755)

Lag1 0.03527(0.02129)

Lag2 0.06449(0.02154)

Lag3 0.05177(0.01871)

Lag4 0.04434(0.02056)

Lag5 0.05940(0.02100)

Thevaluesinboldindicatep<0.05.

80.0

60.0

40.0

20.0

0.0

–20.0

Lag 0 Lag 1 Lag 2 Lag 3 Lag 4 Lag 5

Figure1 Percentageincreasesoftherelativerisksand corre-sponding95%confidenceintervalsforalllagsafteranincrement of5␮g/m3inPM2.5concentrations.Taubaté,Brazil,2011---2012.

percentagepointsinhospitalizationrisks.Fig.2shows the

dailyPM2.5concentrationsduringthestudyperiod.

Discussion

Thisstudyuseddataonpollutantsestimatedbythe CCATT-BRAMS system,which considersthe atmosphericdynamics anddemonstratedapositiveassociationbetweenexposure toPM2.5 andhospitalizationsforpneumoniaandasthmain

childrenlivinginthecityofTaubaté(SP).

The CCATT-BRAMSsystemisamathematicalmodelthat comprehendsSouthAmericaandconsiderstheemissionand

45.0

40.0

35.0

25.0

15.0

5.0

0.0

01/08/

11

01/10/

11

01/12/

11

01/02/12 01/04/12 01/06/12 01/08/12 01/10/12 01/12/12 30.0

20.0

10.0

Figure2 Dailyvalues, in␮g/m3,oftheparticulatematter

<2.5 microns of aerodynamic diameter pollutant concentra-tions.Taubaté,Brazil,2011---2012.

transportofdifferentgasesandaerosolparticles,obtained by satellites, and generates daily estimates for different pollutants.17_The_model_provides_PM

2.5measurementsevery

3hover a gridof cells with30km×30km. Dailyarithmetic

meansofPM2.5concentrationswerecalculatedbasedonthe

meansofthesetofcellsthatcomprisetheterritoryareaof

theassessedmunicipality.

Theuseofdataestimatedbythissystem,whichhasbeen

validatedbyIgnottietal.,10_Cesar_et_al.11_and_Silva_et_al.,19

isadvantageouswhenappliedtocitieswherethereareno

pollutionmonitoringstations,asisthecaseofTaubaté.This

allows the decrease in research costs and optimizes the

processofanalyzingtheeffectsofairpollutiononhealth.

However, the fact that CCATT-BRAMS measures are

esti-matedat an altitudeof40m, andnotin regionscloser to

theground,wheretheconcentrationscanbedifferent,may

representalimitationofthisstudy.11

Duringthestudyperiod,itwasobservedthat

hospitaliza-tionsforpneumoniaandasthma inchildrenagedupto10

yearsshowedasignificant positive association withPM2.5,

both ontheexposure day (lag0) and fromthesecond to

thefifthdayoftheexposure(lags2---5),suggestinganacute

effecttoexposure.Theacuteeffectsmanifestafterashort

timebetweenexposureandtheeffects,whichcanbehours

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Epidemiological studies show thatexposure to gaseous

pollutantsandparticulatematterisassociatedwithahigher

incidenceoflowerrespiratorysymptomssuchascough,

dys-pneaandwheezing,especiallyinchildren.2

InTaubaté(SP),themainsourceofairpollutantsisthe

burningoffossilfuelsbythevehiclefleetofthe

municipal-ity,whichhasthehighestnumberofvehiclesperinhabitant

(64.5 vehicles/100 inhabitants)21 _when _compared _to _the

othercitieslocatedinValedoParaíba(SP).Another

impor-tantcontributionisbroughtonbythefleetthatgoesthrough

Presidente Dutra interstate highway, consisting mainly of

busesandheavytrucks.Thestudyofrecentdatafromthe

cityofSãoJosédosCampos (SP)showedthattherewasa

decreaseinhospitalizationsforpneumoniainchildrenwith

thereductionofSO2andPM10concentrations,buttherewas

anassociationbetweenexposuretocarbonmonoxide(CO)

andozone(O3)andhospitalizations.Thissuggeststhatthe

effectsofcontrolmeasuresimplementedintheperiodwere

neutralizedbytheincreaseinthevehiclefleet.23

Inurban areas,exposure toairpollutants is

character-izedbylongperiodsandlowlevelsofpollutants,3_unlike_air

pollutionoriginatingfromwildfires,ofwhichmain

charac-teristicisthewell-definedseasonalityandhighlevelsmainly

ofparticulatematter.19_The_burning_of_biomass,_as_shown_by

theresultsofPiracicaba(SP)andtheAmazonregion,hasan

importantroleinpollutantconcentrations.7,10,11

StudiesinBrazilshowtheinfluenceofPM10inthegenesis

ofhospitalizationsforrespiratorydiseasesinchildren.3,4,24

However,thefine(PM2.5)particulateisscarcelystudied,as

itis not quantifiedby theenvironmental agencystations;

recently,nationalstudieswerepublisheddemonstratingthe

roleofthisfractioninthegenesisofhospitaladmissionsfor

respiratorydiseases.10,11,19_In_Taubaté,_the_RRs_of

hospital-izationsforpneumoniaandasthmarangedbetween4.1%and

6.3%.Althoughlow,theriskswerehigherthanthosefound

inPiracicaba(SP).11 _In_Taubaté,_an _increase _of₅

␮g/m3 in

PM2.5concentrations impliesinsignificant increasesinthe

riskof hospitalization,between20.3 and38.4percentage

points.

The findings of this study agree with those of other

national articles7,10,11 _and _the _results _of _{Hertz-Picciotto}

etal.,25_who_pointed_out_the_role_of_this_pollutant_in

hospi-talizationsforlowerrespiratorytractinfectionsinpreschool

children in the Czech Republic. Karr et al.,13 _using

con-ditionallogisticregression,showedthat exposuretoPM2.5

was associated with increased risk of hospitalization for

childhood bronchiolitis (OR=1.09; 95%CI: 1.04---1.14). The

aforementioned national studies used data estimated by

modelsandthestudiesbyHertz-Picciottoetal.25 _and_Karr

et al.13 _used _data _collected _by _monitoring _stations. _The

potentialmechanismsbywhichPM2.5canleadtorespiratory

diseases are numerous, including oxidative stress,

struc-turaldamage,efficienttransportofpathogensandimmune

systemalterations,possiblycorrelatedwithcarbonorganic

compounds.26

Another important point to be highlighted is the

increasedhospital costs due tohospitalizations for

respi-ratorydiseasesassociatedwithexposuretofineparticulate

matter.27 _In_this_study,_it_was_estimated_that_the_reduction

in5␮g/m3in PM2.5concentrationinthe atmospherecould

contributetothedecreasein 38pediatrichospitalizations

forpneumoniaandasthmainTaubaté,withintheperiodof

oneyear,whichwouldresultinsavingsofR$84,000forthe

BrazilianUnifiedHealthSystem(SUS).

This study haslimitations, some of whichare inherent

to ecologicalstudies; the fact of working withsecondary

data, eventhosefromofficialsourcescommonly usedfor

studies on this subject, allows the possibility of

diagno-sis coding errors,in addition tothe fact that these data

donotprovideinformationaboutcomorbidities,smokingin

thehome(passivesmoking)andparentaleducation,among

otherassociatedfactors.Thissourcehasthebasic

account-ing purposeandthe provideddata onhospital admissions

are restricted to the users of the Unified Health System,

excluding informationon children treated throughhealth

insurancecompaniesorinprivateclinics.Anotherlimitation

of this study may lie in the fact the CCATT-BRAMS

meas-uresareestimatedat analtitudeof40m,andnotinareas

closertotheground,whereconcentrationscanbedifferent;

furthermore,itwasassumedthattheconcentrationswere

homogeneousandthatchildrenwereequallyexposedtoair

pollutants,especiallytothefineparticulate,considerations

thatcouldrepresentanotherpossiblelimitation.

Despitethestrongbiologicalplausibility,ourresults

can-notallowustopresumethattherearecausalassociations.

Furtherinvestigationsareneededontherolesofother

pol-lutants,suchasO3,PM10,CO,NO2andmetals,whichhave

beenassociatedwithadiversityofrespiratorydiagnoses.

Therefore,exposure to PM2.5 was associatedwith

hos-pitalizationsforpneumoniaandasthmainchildrenyounger

than10yearsofageinamedium-sizedcity.Thisinformation

corroborates the findings from other studies and

demon-strates theimportantroleof fine particulateinchildren’s

health,inadditiontoprovidingsubsidiesforthe

implemen-tationofpreventivemeasurestoreducetheseoutcomes.

Funding

Thestudyreceivednofunding.

Conflicts

of

interests

Theauthorsdeclarenoconflictsofinterest.

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