Ambient (outdoor) air pollution - WHO | World Health ...

WHO fact sheet on ambient (outdoor) air quality guidelines: includes key facts, definition, health effects, guideline values and WHO ... Home/ Newsroom/ Factsheets/ Detail/ Ambient(outdoor)airpollution Ambient(outdoor)airpollution 22September2021 Keyfacts Airpollutionisoneofthegreatestenvironmentalrisktohealth.Byreducingairpollutionlevels,countriescanreducetheburdenofdiseasefromstroke,heartdisease,lungcancer,andbothchronicandacuterespiratorydiseases,includingasthma. Thelowerthelevelsofairpollution,thebetterthecardiovascularandrespiratoryhealthofthepopulationwillbe,bothlong-andshort-term. TheWHOAirQualityGuidelines:GlobalUpdate2021provideanassessmentofhealtheffectsofairpollutionandthresholdsforhealth–harmfulpollutionlevels. In2019,99%oftheworldpopulationwaslivinginplaceswheretheWHOairqualityguidelineslevelswerenotmet. Ambient(outdoorairpollution)inbothcitiesandruralareaswasestimatedtocause4.2millionprematuredeathsworldwidein2016. Some91%ofthoseprematuredeathsoccurredinlow-andmiddle-incomecountries,andthegreatestnumberintheWHOSouth-EastAsiaandWesternPacificregions. Policiesandinvestmentssupportingcleanertransport,energy-efficienthomes,powergeneration,industryandbettermunicipalwastemanagementwouldreducekeysourcesofoutdoorairpollution. Inadditiontooutdoorairpollution,indoorsmokeisaserioushealthriskforsome2.6billionpeoplewhocookandheattheirhomeswithbiomass,kerosenefuelsandcoal. BackgroundOutdoorairpollutionisamajorenvironmentalhealthproblemaffectingeveryoneinlow-,middle-,andhigh-incomecountries.Ambient(outdoor)airpollutioninbothcitiesandruralareaswasestimatedtocause4.2millionprematuredeathsworldwideperyearin2016;thismortalityisduetoexposuretofineparticulatematterof2.5micronsorlessindiameter(PM2.5),whichcausecardiovascularandrespiratorydisease,andcancers.Peoplelivinginlow-andmiddle-incomecountriesdisproportionatelyexperiencetheburdenofoutdoorairpollutionwith91%(ofthe4.2millionprematuredeaths)occurringinlow-andmiddle-incomecountries,andthegreatestburdenintheWHOSouth-East AsiaandWesternPacificregions.Thelatestburdenestimatesreflecttheverysignificantroleairpollutionplaysincardiovascularillnessanddeath.Moreandmore,evidencedemonstratingthelinkagesbetweenambientairpollutionandthecardiovascular diseaseriskisbecomingavailable,includingstudiesfromhighlypollutedareas.WHOestimatesthatin2016,some58%ofoutdoorairpollution-relatedprematuredeathswereduetoischaemicheartdiseaseandstroke,while18%ofdeathswereduetochronicobstructivepulmonarydiseaseandacutelowerrespiratoryinfectionsrespectively, and6%ofdeathswereduetolungcancer.Somedeathsmaybeattributedtomorethanoneriskfactoratthesametime.Forexample,bothsmokingandambientairpollutionaffectlungcancer.Somelungcancerdeathscouldhavebeenavertedbyimprovingambientairquality,orbyreducingtobacco smoking.A2013assessmentbyWHO’sInternationalAgencyforResearchonCancer(IARC)concludedthatoutdoorairpollutioniscarcinogenictohumans,withtheparticulatemattercomponentofairpollutionmostcloselyassociatedwithincreasedcancerincidence, especiallylungcancer.Anassociationalsohasbeenobservedbetweenoutdoorairpollutionandincreaseincanceroftheurinarytract/bladder.Addressingallriskfactorsfornoncommunicablediseases–includingairpollution–iskeytoprotectingpublichealth.Mostsourcesofoutdoorairpollutionarewellbeyondthecontrolofindividualsanddemandsconcertedactionbylocal,nationalandregionallevelpolicy-makersworkinginsectorsliketransport,energy,wastemanagement,urbanplanning,andagriculture.Therearemanyexamplesofsuccessfulpoliciesintransport,urbanplanning,powergenerationandindustrythatreduceairpollution:forindustry: cleantechnologiesthatreduceindustrialsmokestackemissions;improvedmanagementofurbanandagriculturalwaste,includingcaptureofmethanegasemittedfromwastesitesasanalternativetoincineration(for useasbiogas);forenergy:ensuringaccesstoaffordablecleanhouseholdenergysolutionsforcooking,heatingandlighting;fortransport: shiftingtocleanmodesofpowergeneration;prioritizingrapidurbantransit,walkingandcyclingnetworksincitiesaswellasrailinterurbanfreightandpassengertravel;shiftingtocleanerheavy-dutydiesel vehiclesandlow-emissionsvehiclesandfuels,includingfuelswithreducedsulfurcontent;forurbanplanning: improvingtheenergyefficiencyofbuildingsandmakingcitiesmoregreenandcompact,andthusenergyefficient;forpowergeneration: increaseduseoflow-emissionsfuelsandrenewablecombustion-freepowersources(likesolar,windorhydropower);co-generationofheatandpower;anddistributedenergygeneration(e.g.mini-gridsand rooftopsolarpowergeneration);formunicipalandagriculturalwastemanagement: strategiesforwastereduction,wasteseparation,recyclingandreuseorwastereprocessing;aswellasimprovedmethodsofbiologicalwastemanagementsuchasanaerobicwaste digestiontoproducebiogas,arefeasible,lowcostalternativestotheopenincinerationofsolidwaste.Whereincinerationisunavoidable,thencombustiontechnologieswithstrictemissioncontrolsarecritical.Inadditiontooutdoorairpollution,indoorsmokefromhouseholdairpollutionisaserioushealthriskforsome2.6billionpeoplewhocookandheattheirhomeswithbiomassfuelsandcoal.Some3.8millionprematuredeathswereattributabletohouseholdairpollutionin2016.Almostalloftheburdenwasinlow-middle-incomecountries.Householdairpollutionisalsoamajorsourceofoutdoorairpollutioninbothurbanandruralareas,accountingforupto50%insomeregionsoftheworld.The WHOGlobalairqualityguidelinesofferglobalguidanceonthresholdsandlimitsforkeyairpollutantsthatposehealthrisks.TheGuidelinesapplyworldwidetobothoutdoorandindoorenvironmentsandarebasedonexpertevaluationofcurrentscientificevidencefor:particulatematter(PM)ozone(O3)nitrogendioxide(NO2)sulfurdioxide(SO2).TheGuidelinesalsoincludequalitativegoodpracticerecommendationsforblackcarbon/elementalcarbon,ultrafineparticles(<=1um)andparticlesderivedfromsandandduststorms. Particulatematter(PM)DefinitionandprincipalsourcesPMisacommonproxyindicatorforairpollution.Itaffectsmorepeoplethananyotherpollutant.ThemajorcomponentsofPMaresulfate,nitrates,ammonia,sodiumchloride,blackcarbon,mineraldustandwater.Itconsistsofacomplexmixtureofsolid andliquidparticlesoforganicandinorganicsubstancessuspendedintheair.Whileparticles withadiameterof10micronsorless,(≤PM10)canpenetrateandlodgedeepinsidethelungs,theevenmorehealth-damagingparticles arethosewithadiameterof2.5micronsorless,(≤PM2.5).PM2.5 canpenetratethelungbarrierandenterthebloodsystem.Chronicexposuretoparticlescontributestotheriskofdevelopingcardiovascularandrespiratory diseases,aswellasoflungcancer.AirqualitymeasurementsaretypicallyreportedintermsofdailyorannualmeanconcentrationsofPM10 particlespercubicmeterofairvolume(m3).RoutineairqualitymeasurementstypicallydescribesuchPMconcentrations intermsofmicrogramspercubicmeter(μg/m3).Whensufficientlysensitivemeasurementtoolsareavailable,concentrationsoffineparticles(PM2.5 orsmaller),arealsoreported.HealtheffectsThereisaclose,quantitativerelationshipbetweenexposuretohighconcentrationsofsmallparticulates(PM10 andPM2.5)andincreasedmortalityormorbidity,bothdailyandovertime.Conversely,whenconcentrationsofsmall andfineparticulatesarereduced,relatedmortalitywillalsogodown–presumingotherfactorsremainthesame.Thisallowspolicy-makerstoprojectthepopulationhealthimprovementsthatcouldbeexpectedifparticulateairpollutionis reduced.Smallparticulatepollutionhashealthimpactsevenatverylowconcentrations–indeednothresholdhasbeenidentifiedbelowwhichnodamagetohealthisobserved.Therefore,theWHOGlobalguidelinelimitsaimedtoachievethelowestconcentrationsofPMpossible. WHOAirqualityguidelinevaluesParticulatematter(PM)GuidelinevaluesFineparticulatematter(PM2.5)5μg/m3 annualmean15μg/m3 24-hourmeanCoarseparticulatematter(PM10)15μg/m3 annualmean45μg/m3 24-hourmeanInadditiontoguidelinevalues,theWHOGlobalairqualityguidelinesprovideinterimtargetsforconcentrationsofPM10 andPM2.5 aimedatpromotingagradualshiftfromhightolowerconcentrations.Iftheseinterimtargetsweretobeachieved,significantreductionsinrisksforacuteandchronichealtheffectsfromairpollutioncanbeexpected.Achievingtheguidelinevalues,however,shouldbetheultimateobjective.TheeffectsofPMonhealthoccuratlevelsofexposurecurrentlybeingexperiencedbymanypeoplebothinurbanandruralareasandindevelopedanddevelopingcountries–althoughexposuresinmanyfast-developingcitiestodayareoftenfarhigher thanindevelopedcitiesofcomparablesize.Inlow-andmiddle-incomecountries,exposuretopollutantsinandaroundhomesfromthehouseholdcombustionofpollutingfuelsonopenfiresortraditionalstovesforcooking,heatingandlightingfurtherincreasestheriskforairpollution-related diseases,includingacutelowerrespiratoryinfections,cardiovasculardisease,chronicobstructivepulmonarydiseaseandlungcancer.ThereareseriousriskstohealthnotonlyfromexposuretoPM,butalsofromexposuretoozone(O3),nitrogendioxide(NO2)andsulfurdioxide(SO2).AswithPM,concentrationsareoftenhighestlargelyintheurbanareas oflow-andmiddle-incomecountries.Ozoneisamajorfactorinasthmamorbidityandmortality,whilenitrogendioxideandsulfurdioxidealsocanplayaroleinasthma,bronchialsymptoms,lunginflammationandreducedlungfunction. Ozone(O3)GuidelinevaluesO3100μg/m3,8-hourdailymaximum*60μg/m38-hourmean,peakseason***99thpercentile,(i.e.3-4exceedancedaysperyear)**Peakseasonisdefinedasanaverageofdailymaximum8-hourmeanO3concentrationinthesixconsecutivemonthswiththehighestsix-monthrunningaverageO3concentrationDefinitionandprincipalsourcesOzoneatgroundlevel–nottobeconfusedwiththeozonelayerintheupperatmosphere–isoneofthemajorconstituentsofphotochemicalsmog.Itisformedbythereactionwithsunlight(photochemicalreaction)ofpollutantssuchasnitrogen oxides(NOx)fromvehicleandindustryemissionsandvolatileorganiccompounds(VOCs)emittedbyvehicles,solventsandindustry.Asaresult,thehighestlevelsofozonepollutionoccurduringperiodsofsunnyweather.HealtheffectsExcessiveozoneintheaircanhaveamarkedeffectonhumanhealth.Itcancausebreathingproblems,triggerasthma,reducelungfunctionandcauselungdiseases. Nitrogendioxide(NO2)GuidelinevaluesNO210μg/m3 annualmean25μg/m3 24-hourmeanThecurrentWHOguidelinevalueof10µg/m3 (annualmean)wassettoprotectthepublicfromthehealtheffectsofgaseousnitrogendioxide.DefinitionandprincipalsourcesNO2isthemainsourceofnitrateaerosols,whichformanimportantfractionofPM2.5and,inthepresenceofultravioletlight,ofozone.ThemajorsourcesofanthropogenicemissionsofNO2arecombustionprocesses(heating,powergeneration,andenginesinvehiclesandships).HealtheffectsEpidemiologicalstudieshaveshownthatsymptomsofbronchitisinasthmaticchildrenincreaseinassociationwithlong-termexposuretoNO2.ReducedlungfunctiongrowthisalsolinkedtoNO2 atconcentrationscurrentlymeasured (orobserved)incitiesofEuropeandNorthAmerica. Sulfurdioxide(SO2)GuidelinevaluesSO240μg/m324-hourmean StudiesindicatethataproportionofpeoplewithasthmaexperiencechangesinpulmonaryfunctionandrespiratorysymptomsafterperiodsofexposuretoSO2.HealtheffectsarenowknowntobeassociatedwithmuchlowerlevelsofSO2thanpreviouslybelieved.Agreaterdegreeofprotectionisneeded.AlthoughthecausalityoftheeffectsoflowconcentrationsofSO2isstilluncertain,reducingSO2concentrationsislikelytodecreaseexposuretoco-pollutants.DefinitionandprincipalsourcesSO2 isacolourlessgaswithasharpodour.Itisproducedfromtheburningoffossilfuels(coalandoil)andthesmeltingofmineraloresthatcontainsulfur.ThemainanthropogenicsourceofSO2 istheburningofsulfur-containing fossilfuelsfordomesticheating,powergenerationandmotorvehicles.HealtheffectsSO2 canaffecttherespiratorysystemandthefunctionsofthelungs,andcausesirritationoftheeyes.Inflammationoftherespiratorytractcausescoughing,mucussecretion,aggravationofasthmaandchronicbronchitisandmakespeople morepronetoinfectionsoftherespiratorytract.HospitaladmissionsforcardiacdiseaseandmortalityincreaseondayswithhigherSO2 levels.WhenSO2 combineswithwater,itformssulfuricacid;thisisthemain componentofacidrainwhichisacauseofdeforestation. WHOresponseWHOMemberStatesrecentlyadoptedaresolution(2015)andaroadmap(2016)foranenhancedglobalresponsetotheadversehealtheffectsofairpollution.WHOiscustodialagencyfor3airpollution-relatedSustainableDevelopmentGoalsindicators:3.9.1Mortalityfromairpollution7.1.2Accesstocleanfuelsandtechnologies11.6.2Airqualityincities.WHOdevelopsandproducesairqualityguidelinesrecommendingexposurelimitstokeyairpollutants(indoorandoutdoor).WHOcreatesdetailedhealth-relatedassessmentsofdifferenttypesofairpollutants,includingparticulatesandblackcarbonparticles,andozone.WHOproducesevidenceregardingthelinkageofairpollutiontospecificdiseases,suchascardiovascularandrespiratorydiseasesandcancers,aswellasburdenofdiseaseestimatesfromexistingairpollutionexposures,atcountry,regional,andglobal levels.WHOdevelopstoolssuchasAirQ+forassessingthehealthimpactsfromvariouspollutants,butalsotheHealthEconomicAssessmentTool(HEAT)toassesswalkingandcyclinginterventions,theGreen+tooltoraiseimportanceofgreenspaceandhealth, theSustainableTransportHealthAssessmentTool(STHAT)andtheIntegratedTransportandHealthImpactModellingTool(ITHIM).WHOhasdevelopedaCleanHouseholdEnergySolutionsToolkit(CHEST)toprovidecountriesandprogrammeswiththetoolsneededtocreateorevaluatepoliciesthatexpandcleanhouseholdenergyaccessanduse,whichisparticularlyimportantaspollutants releasedinandaroundthehousehold(householdairpollution)contributesignificantlytoambientpollution.CHESTtoolsincludemodulesonneedsassessment,guidanceonstandardsandtestingforhouseholdenergydevices,monitoringandevaluation, andmaterialstoempowerthehealthsectortotacklehouseholdairpollution.WHOassistsMemberStatesinsharinginformationonsuccessfulapproaches,onmethodsofexposureassessmentandmonitoringofhealthimpactsofpollution.WHOisleadingtheJointTaskForceontheHealthAspectsofAirPollution withintheConventiononLong-rangeTransboundaryAirPollutiontoassessthehealtheffectsofsuchpollutionandtoprovidesupportingdocumentation.TheWHOco-sponsoredPanEuropeanProgrammeonTransportHealthandEnvironment(PEP),hasbuiltamodelofregional,MemberState,andmultisectoralcooperationformitigationofairpollutionandotherhealthimpactsinthetransportsector,aswell astoolsforassessingthehealthbenefitsofsuchmitigationmeasures.  Related RelatedlinksWHOGlobalHealthObservatoryRecentdataonairquality.Airpollutionandcancer:IARC’s2013assessmentReviewofevidenceonthehealthaspectsofairpollution(REVIHAAP)WHO'sworkonindoorairpollutionandhealthWHORegionalOfficeforEurope'sworkonairquality News NewWHOGlobalAirQualityGuidelinesaimtosavemillionsoflivesfromairpollution 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