Why do the values shown on the IRCELINE website differ from ...

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Aqicn.org uses the index of the American Environmental Protection Agency (US EPA). However, to compute this index for particulate matter (PM2.5), AQICN ... Skiptocontent.| Skiptonavigation PersonaltoolsNavigation Nederlands English Français Deutsch SearchSite AdvancedSearch… AirQualityDocumentationAboutUsForum You arehere: Home / News / WhydothevaluesshownontheIRCELINEwebsitedifferfromthoseonaqicn.org? Info WhydothevaluesshownontheIRCELINEwebsitedifferfromthoseonaqicn.org? TheairqualitymeasurementsthatareshownontheIRCEL-CELINEwebsiteforthedifferentpollutants(PM10,PM2.5,NO2,ozone,"blackcarbon",etc.)areconcentrationsexpressedasmicrogramspercubicmeter(µg/m³),orasmassperunitofvolume.Microgrampercubicmeterisaconventionalandthemostfrequentlyusedunitinthefieldofthe scientificanalysisofairpollution. TheEuropeantargetandthresholdvaluesasgivenintheEuropeandirectives,arealsoexpressedinµg/m³.Inthesameway,theWHOrecommendationsareexpressedasµg/m³.Asanexample,thedailylimitforPM10asdescribedindirective2008/50/ECis50µg/m³,nottobeexceededonmorethan35daysperyear,whiletheWHOrecommendationonthedailyPM10limitconcentrationis50µg/m³,nottobeexceededonmorethan3daysperyear. OntheIRCEL-CELINEwebsite,theairqualitydatameasuredbythetelemetricnetworksofthethreeRegionsispublishedinrealtimeandupdatedonanhourlybasis.Thesemeasurementsare,aftervalidationbytheauthorisedregionalenvironmentalagencies,alsousedforthemandatoryannualreportingonBelgianairqualitytotheEuropeanCommission. TheairqualitydataontheIRCEL-CELINEwebsitearepubliclyaccessible.Throughso-called'webservices',theycanbeusedbyexternalusers,forinstancetodevelopsmartphoneapps.Assuch,aqicn.orgalsousestheseservices.Theairqualitydatashownon//www.aqicn.orgarederivedfromtheIRCEL-CELINEwebsite.However,thevaluespublishedbyAQICNarenotconcentrations,but"indexnumbers".ThedatafromIRCEL-CELINEarethusfirstconvertedby AQICNtodimensionlessnumbers,tocondensetheconcentrationsofmultiplepollutantsintoasinglenumber.Indexesservethepurposeofallowingasimpleyetqualitativeevaluationofairquality,suchastheBelATMOindexinBelgium.Worldwide,variousairqualityindexesareused. Aqicn.orgusestheindexoftheAmericanEnvironmentalProtectionAgency(USEPA).However,tocomputethisindexforparticulatematter(PM2.5), AQICNerroneouslyuseshourlymeasuredparticulatematterconcentrations,whiletheUSEPAindexforparticulatematterisbasedon24-hourlymeanconcentrations.Thelatterislegitimate,since24-hourlymeanconcentrationsareusedinepidemiologicalstudieswhichinvestigatetheshorttermhealtheffectscausedbyparticulatematter.Theindexvalueonaqicn.orgisonlycorrectiftheconcentrationsdonotchangeinthefollowing23hours. ThecorrectconversionbetweenconcentrationsandtheEPAindexcanbecalculatedwiththefollowingonlineapplication:https://www.airnow.gov/index.cfm?action=airnow.calculator Navigation AnnualReportAirQualityinBelgium2011 TheEuropeanenvironment–stateandoutlook2015 NewthresholdforparticulatematterinthethreeRegions WhydothevaluesshownontheIRCELINEwebsitedifferfromthoseonaqicn.org? SiteMap Accessibility Contact Follow@SMOG_BE

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