AirQuality,EnergyandHealthScienceandPolicySummaries

Airqualitylegislationandimplicationsforhealth

Technicalbrief

Keymessages

?Thereisalargebodyofevidenceontheadversehealtheffectsofairpollution,whichisthebasisfordevelopingtheWorldHealthOrganization(WHO)airqualityguidelines.

?TheWHOairqualityguidelinesareasetofnon-bindingevidence-based

recommendationsoflimitvaluesforspecificairpollutantsdevelopedtosupportcountriesinestablishingairqualitylegislation,includingairqualitystandards

(AQS),toprotectpublichealth.

?InformationonAQSforselectedpollutants–agivenlevelofairpollutantwhichisadoptedandenforcedbyaregulatoryauthority–iscurrentlypubliclyavailablefor

128countries.Thereisgreatheterogeneityinboththeiravailabilityandthelevelschosenasstandardsacrosscountriesandregions.

?Airqualitystandardsarepartofapackageoflegislativemeasurestoreducethe

healthrisksofairpollution.Othermeasuresincludesourcecontrol,landuseplanningandtransportationmeasures.

?Effectiveairqualitylawsandregulations,whichincludeAQS,aretwoofthekeypolicyactionstosignificantlyimproveairqualityandprotecthealth.

?LegislationwhichembedsAQScanenablenationalairqualitymanagementtobeoperationalizedthroughtheestablishmentofrobustinstitutionalandgovernancestructures.

?InadditiontoAQS,legislationshouldalsointegratereliableandrepresentativemeasurementofairqualityaspartofaneffectivemonitoringsystem,and

accountabilityandenforcementmechanisms.

worldHealthorganization

Airqualitylegislationandimplicationsforhealth:Technicalbrief2

Keydefinitions

Airqualityguidelines:AseriesofWHOpublicationsprovidingevidence-

informed,non-bindingrecommendationsforprotectingpublichealthfromtheadverseeffectsofairpollutantsbyeliminatingorreducingexposuretohazardousairpollutantsandbyguidingnationalandlocalauthoritiesintheirriskmanagementdecisions.Thelatestvolumewaspublishedin2021(1).

Airqualitystandard:Agivenlevelofanairpollutant(forexample,a

concentrationordepositionlevel)thatisadoptedbyaregulatoryauthorityasenforceable.Unlikeanairqualityguidelinelevel,anumberofelementsinadditiontotheeffect-basedlevelandaveragingtimemustbespecifiedintheformulationofanairqualitystandard(1).

Legislation:Thisincludesalllawsandregulationsestablishedbyanyformalstate-sponsoredlegislativeprocess,inaccordancewiththeconstitutional

structureandnormsoftherelevantcountry(2).

MonitoringairpollutioninJohannesburg,FondLuminisSchool,Diepkloof

?ClimateVisuals/GulshanKhan

Airqualitylegislationandimplicationsforhealth:Technicalbrief3

Overview

FromhealthstudiestotheWHOairqualityguidelines

WHOhasbeencompilingandreviewingevidenceonthehealtheffectsofairpollutionsincethe1950s(3,4).Today,awiderangeofdiseasesarewelldocumented,asshort-termeffects(withexposuresofhoursanddays)andlong-termeffects(monthsandyears),foralmostallorgansystems(includingrespiratory,cardiovascular,nervousandmetabolicsystems,aswellastheoutcomeofpregnancy),andforallages.

SeeSPS1:Healtheffectsofairpollution-evidenceandimplications

Airpollutionisacomplexmixtureforwhichseveralcomponentshavelongbeencoveredbystandards.Thesepollutants–particulatematter(PM),ozone(O3),nitrogendioxide(NO2),

carbonmonoxide(CO)andsulfurdioxide(SO2)–havebeenstudiedextensivelyandthe

resultingevidenceissufficientlyrobusttosupportstandardsforeachpollutant.Additionally,regulationofthesepollutantsaddressesthemajorcontributorstoambientairpollution.

Basedonthescientificknowledge,thefirsteditionoftheWHOairqualityguidelineswas

publishedin1987(5),providingrecommendationsonairqualityguidelinelevelsforselectedairpollutants.Theairqualityguidelinelevelsaddressambientairpollutionandcoverthe

manymicro-environmentswherepeoplespendtime.Rapidlygrowingevidenceofthe

healtheffectsofairpollutants–PM,O3,NO2,COandSO2–providedthebasisforthelatestglobalupdateoftheWHOairqualityguidelinesin2021,basedonthehealthoutcomes

thatarecriticalfordecision-makingandforbothlong-andshort-termperiodsofexposure(seeTable1)(1).GuidelinesonawidersetofpollutantsareprovidedinpreviousvolumesoftheWHOairqualityguidelines(6,7).

1ScienceandPolicySummary

Anairpollutiondetectorsystemstationinapark

?AdobeStock/PixelB

Airqualitylegislationandimplicationsforhealth:Technicalbrief4

Table1.Summaryofrecommended2021airqualityguidelines(AQG)levelsandinterimtargets(IT)

Pollutant

Averagingtime

IT1

IT2

IT3

IT4

Airquality

guidelineslevel

PM??(μg/m3)

.

Annual

35

25

15

10

5

PM??(μg/m3)

.

24-houra

75

50

37.5

25

15

PM??(μg/m3)

Annual

70

50

30

20

15

PM??(μg/m3)

24-houra

150

100

75

50

45

O?(μg/m3)

Peakseason?

100

70

–

–

60

O?(μg/m3)

8-hour

160

120

–

–

100

NO?(μg/m)3

Annual

40

30

20

–

10

NO?(μg/m3)

24-houra

120

50

–

–

25

NO?(μg/m3)

1-hour

–

–

–

–

200

SO?(μg/m3)

24-houra

125

50

–

–

40

SO?(μg/m3)

10-minute

–

–

–

–

500

CO(mg/m3)

24-houra

7

–

–

–

4

CO(mg/m3)

8-hour

–

–

–

–

10

CO(mg/m3)

1-hour

–

–

–

–

35

CO(mg/m3)

15-minute

–

–

–

–

100

Notes:a99thpercentile(i.e.3–4exceedancedaysperyear);bAverageofdailymaximum8-hourmeanozoneconcentrationinthe6consecutivemonthswiththehighest6-monthrunning-averageozoneconcentration.COcarbonmonoxide;ITinterimtarget;NO2nitrogendioxide;O3ozone;PMparticulatematter;

SO2sulfurdioxide.

Airqualityguidelinelevel

Theairqualityguidelinelevelisaspecificformatofaguidelinerecommendationconsistingofanumericalvalue,expressedasaconcentrationofacertainpollutantintheairand

linkedtoanaveragingtime(i.e.thedurationoftheexposurewithagivenmeanairpollutantconcentrationassociatedwithcertainhealtheffects).Insettingtheairqualityguidelines,

WHOfoundevidencethatadversehealtheffectsdonotoccurorareminimalbelowthis

concentrationlevel.However,completeexclusionofharmfuleffectsatconcentrationsbelowthegivenvalueisuncertainandcannotbeguaranteed.

Interimtargets

Sincethe2005version,WHOairqualityguidelineshavealsoprovidedinterimtargetsfor

selectedpollutants–airpollutantconcentrationsassociatedwithaspecificdecreaseof

healthriskonthepathtoachievingtheairqualityguidelinelevels.Interimtargetsserve

tostimulatepolicy-makerstotakeincrementalstepsintheprogressivereductionofair

pollutiontowardstheairqualityguidelinelevels,particularlyforthosecountrieswellabovethelevels.Designedespeciallyforareaswithhighpollution,thesetargetssetpollutantlevelsabovetheairqualityguidelinestandardsbutprovideachievablemilestonesfordevelopingeffectivereductionpolicies.Therefore,theinterimtargetsshouldberegardedassteps

towardstheultimateachievementofairqualityguidelinelevelsinthefuture,ratherthantheendgoalforthosecountriesusingthetargetsforregulationanddecision-making(8).

Airqualitylegislationandimplicationsforhealth:Technicalbrief5

FromWHOairqualityguidelinestoairqualitystandards

Airqualitystandardsaimtoreducelevelsofairpollutantsanddecreasethehealth

burdenassociatedwithairpollution.Whilstnotlegallybinding,likeallWHOguidelines,

theairqualityguidelinesareanevidence-informedtoolfordecision-makerstoguidethe

developmentandupdatingofnationalAQS,legislation,policiesandprogrammaticplanning.

AfirstcomprehensivereviewandcompilationofAQSfor194countriesin2017provided

someinsightsonhowtheWHOairqualityguidelinesareutilized.FindingsshowedthatAQSvarygreatlyamongregionsandcountries,andthesediscrepanciesamplifythedifferencesinairqualityandrelatedhealtheffectsaroundtheworld.OnlyahandfulofcountrieshadAQSinlinewithWHOguidelinevalues.Ingeneral,AQSforPM2.5,PM10andSO2rarelycomplied

withWHOguidelinevalues(9).AmorerecentreviewintheWHOEasternMediterranean

Regionshowedthatalmostall(19outof22)countrieshaveAQS,butthatthestandards’concentrationsareupto10timestherecommended2021WHOguidelinesvalues,forPM2.5forexample(10).

AnupdateofthiscompilationofAQShasrecentlybeenpublishedasadatabase–the

WHO

AirQualityStandardsDatabase

(11).InformationisavailableonAQSforselectedpollutantsandaveragingtimesfor194WHOMemberStates,ofwhich128countries,includingEuropeanUnioncountries,haveestablishedAQS.ThealignmentoftheAQSforPM2.5(annual)withtheWHOairqualityguidelinesispresentedinFig.1.ForallWHOregionsexceptAfrica,morethan30%ofcountrieswithintheregionshaveastandardforPM2.5,withEuropepeakingat78%.

Fig.1.PercentageofcountrieswithAQSforPM2.5(annual),byWHOregionandairqualityguidelineslevels

90%

80%

70%

60%

50%

40%

30%

20%

10%

0%

AfricanAmericas

European

South-EastAsia

WesternPacific

Eastern

Mediterranean

EqualorbelowAQG(5ug/m3)>5to≤10ug/m3

>10to≤15ug/m3

>15to≤25ug/m3

>25to≤35ug/m3Above35ug/m3

Note:FortheEuropeanUnion27countries,thenewvalueof10mg/m3isconsidered.

Source:WHOAirQualityStandardsDatabase:interactivetool(update2025).Version2.2.Geneva:WorldHealthOrganization;2025(11).

Airqualitylegislationandimplicationsforhealth:Technicalbrief6

Legislationandambientairqualitystandards

Airqualitylawsandregulationsarekeypolicyactionstosignificantlyimproveairquality.

Indeed,effortstoattaintheWHOairqualityguidelinesandtosignificantlyreducethedangerposedbyairpollutiontohumanhealthcannotsucceedwithoutalegalandinstitutional

foundationthatestablishesarobustsystemofairqualitygovernance,asidentifiedbytheUnitedNationsEnvironmentProgramme(UNEP)(12).

Tobetterunderstandthegloballandscapeofnationalairqualitymanagement,UNEP

conductedaglobalassessmentofairpollutionlegislation(GAAPL)in194countriesandtheEuropeanUnion(13),usingtheWHOairqualityguidelinesasastartingpoint2forevaluationofnationalambientAQS.TheGAAPLreportexaminedthelegalmeasuresfordeterminingwhetherAQSarebeingmetandwhatlegaltoolsexistwhentherearefailurestomeetthem.

TheGAAPLreportemphasizedthatrobustairqualitygovernanceiscriticaltoattainingAQSandpublichealthgoals.Thiscanbeachievedthroughdevelopinglegislationforairqualitycontrolwhichintegratesaccountability,enforceability,transparencyandpublicparticipation(seeFig.2).

Fig.2.Airqualitygovernancesystemfoundedinlegislation

Q

Monitoring

toestablishwhether

AQSbeingachieved

Accountability,planning

&sanctions

ifAQSnotachieved

圈

Public

participation&

Institutional

responsibility

rights

forachievingAQS

Airqualitystandardsin legislation

Primaryorsecondary

inairquality

governance

>

Airqualityobjectives

ReviewofAQS

asknowledgedevelops

e.g.highlevelof

humanhealth,

resilientnatural

environment,

sustainable

development

Constitutionalguarantees

tohealthyenvironment

cleanair,etc.

Policy&

regulatorymechanisms

&coordination

rangeofmeasuresfor

achievingAQS,asapropriate

inrelevantcountry

Legislativerequirementsforairqualitygovernance

High-levelpolicy/lawinformingAQS

DeliveringAQSthroughlawandpolicy

Clearreviewprocess

Source:Regulatingairquality:globalassessmentofairpollutionlegislation.UNEP;2021(13).

2Thisstudywasconductedandfinalizedbeforethereleaseoftheupdated2021WHOairqualityguidelines.Thereviewofcountrylegislationthereforeusedthe2005WHOairqualityguidelinesasabenchmark.

Airqualitylegislationandimplicationsforhealth:Technicalbrief7

Whylegislation?Thereportmakesthecasethatlegislativeprocessesarewelladaptedtothecollective,cross-sectoral,evolvingproblemofairpollution.Asknowledgeevolves,

legislativeprocessesallowforthereviewandupdateofregulatoryarrangements,includingstandards.Italsoenableslegitimatepoliticaldeliberationinbalancingsocioeconomic

prioritiestosetanddeliverAQS.Further,legislationprovidesenforceabilityofambientAQSandadministrativeprocessesfordeliveringthem.

Tofunctioneffectively,AQSneedtobeoperationalized.Thisrequirestheestablishment

ofrobustinstitutionalandgovernancestructurestosupportAQS.Italsorequiresreliableinformationaboutairquality,inadditiontoaccountabilityandenforcementmechanisms.LegislativeregimescanconstructadministrativeprocessesandstructuresforimplementingAQS,suchasmonitoringregimes,accountabilityofpublicactorsandformalsanctions.

BasedonthefindingsofGAAPLreport,UNEPdevelopedtheGuideonambientairquality

legislation(2),designedtoassistnationallawmakersindevelopingorimprovingambientairqualitylawsprioritizingpublichealthoutcomes.IttranslateskeyfindingsoftheGAAPLintoconcreteguidanceandconsiderationsforlawmakers.

Specificnationallegalexpertisewillbeneededtoadaptandapplytheguidewithin

nationallegalcontexts.Additionally,theuniquegovernancestructure,politicalcontext

andenvironmentalconditions(suchasairpollutionemissionsourcesandwhoisaffected)ofindividualcountrieswillberelevantinfluencesontheselegislativeprocesses.Forthat

reason,theguidedoesnotproposeamodelforthedevelopmentofairqualitylaws.It

does,however,providethekeyelementsofeffectiveairqualitygovernancethatshouldbeconsideredindevelopingairqualitylegislation,whichcountriescanusetotailorlegislation,accordingtotheirnationalneedsandpriorities.

AQSarethekeydriversforimprovingairquality.Forthisreason,trackingacountry’sactionondevelopingandembeddingAQSinlegislationcanbeusefulinunderstandinghow

countriesaremovingtowardsimprovedairquality.

TheWorldHealthAssembly,aswellastheUnitedNationsEnvironmentAssembly,have

calledonMemberStatestodeveloppoliciestoreduceairpollutionacrosssectors,while

providingsupporttoongoingeffortstoreducein-countryandtransboundaryairpollution(14–16).BothUNEPandWHOareurgingMemberStatestosetambitiousambientAQS,takingintoaccounttheWHOairqualityguidelines(17,18).

Airqualitylegislationandimplicationsforhealth:Technicalbrief8

Wayforward

Capabilitybuildingindevelopingenvironmentallaw

Oneoftheavenuesforachievingthisisthroughsupportingcountriesinbuildingrelevantcapacityinenvironmentallaw(includingairqualitylaw)andcontributingtotheenvironmentaldimensionofthe2030AgendaforSustainableDevelopmentthroughtheintergovernmentalProgrammefortheDevelopmentandPeriodic

ReviewofEnvironmentalLaw(MontevideoProgramme)(19)3.MemberStatesoftheMontevideoProgrammeagreedtothedevelopmentof“l(fā)egalresponsestoaddresstheairpollutioncrisis”asapriorityareaundertheprogramme(20).

CountrysupporttodevelopAQS

WHOandUNEParecontinuouslyworkingtosupportcountriestodeveloporupdateAQSalignedwithWHOairqualityguidelines,aswellastodevelopandimplementambientairqualitylegislation,airqualitymanagementandtracknationalprogresstowardscleanerair.

Acknowledgments

TheWHOgratefullyacknowledgesthemanyindividualsandorganizationswho

contributedtothedevelopmentofthisdocument.ThisdocumentwaswrittenandledbyKarlaCervantes-Martínez,RenéeGift(UNEPLawDivision),SophieGumyandKerolynShairsingh(WHODepartmentofEnvironment,ClimateChangeandHealth).

WHOalsorecognizesthehelpfulcontributionsandpeerreviewprovidedbyMeltemKutlarJoss(SwissTropicalandPublicHealthInstitute,Switzerland),MichalKrzyzanowski(ImperialCollegeLondon),PierpaoloMudu,SamanthaPegoraro,JonathanSamet(ColoradoSchoolofPublicHealth,UnitedStates),andCristinaVert(WHODepartmentofEnvironment,Climate

ChangeandHealth).

TheproductionofthisreportwassupportedbyfundsgenerouslyprovidedbytheClean

AirFund;theForeign,CommonwealthandDevelopmentOfficeoftheGovernmentofthe

UnitedKingdomofGreatBritainandNorthernIreland;theGovernmentoftheKingdomoftheNetherlands;theMinistryofForeignAffairs,EuropeanUnion,andCooperationofthe

GovernmentofSpain;theNorwegianAgencyforDevelopmentCooperation;andtheSpanishAgencyforInternationalDevelopmentCooperation.

Declarationsofinterest

AllexternalexpertssubmittedadeclarationofinteresttoWHOdisclosingpotentialconflictsofinterestthatmightaffect,ormightreasonablybeperceivedtoaffect,theirobjectivity

andindependenceinrelationtothesubjectmatterofthereport.WHOreviewedeachofthedeclarationsandconcludedthatnonecouldgiverisetoapotentialorreasonablyperceivedconflictofinterestrelatedtothesubjectscoveredbythereport.

3Seeparagraph97(d)ofthemedium-termstrategy2022–2025.

Airqualitylegislationandimplicationsforhealth:Technicalbrief9

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