Designation:D7440−08(Reapproved2015)´1StandardPracticeforCharacterizingUncertaintyinAirQualityMeasurements1ThisstandardisissuedunderthefixeddesignationD7440;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.ε1NOTE—EditorialcorrectionsweremadethroughoutinJuly2015.1.Scope1.1Thispracticeisforassistingdevelopersandusersofairqualitymethodsforsamplingconcentrationsofbothairborneandsettledmaterialsincharacterizingmeasurementsastouncertainty.Wherepossible,analysisintouncertaintycompo-nentsasrecommendedintheISOGuidetotheExpressionofUncertaintyinMeasurement(ISOGUM,(1)2)issuggested.Aspectsofuncertaintyestimationparticulartoairqualitymeasurementareemphasized.Forexample,airqualityassess-mentisoftencomplicatedby:thedifficultyoftakingreplicatemeasurementsowingtothelargespatio-temporalvariationinconcentrationvaluestobemeasured;systematicerrororbias,bothcorrectedanduncorrected;andthe(rare)non-normaldistributionoferrors.Thispracticeoperatesmainlythroughexample.Backgroundandmathematicaldevelopmentarerel-egatedtoappendicesforoptionalreading.1.2Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.2.ReferencedDocuments2.1ASTMStandards:3D1356TerminologyRelatingtoSamplingandAnalysisofAtmospheresD3670GuideforDeterminationofPrecisionandBiasofMethodsofCommitteeD22D6246PracticeforEvaluatingthePerformanceofDiffusiveSamplersD6552PracticeforControllingandCharacterizingErrorsinWeighingCollectedAerosols2.2OtherInternationalStandards:ISOGUMGuidetotheExpressionofUncertaintyinMeasurement,ISOGuide98,1995(SeeRef(1),foranadditionalmeasurementuncertaintyresource.)4ISO7708AirQuality—ParticleSizeFractionDefinition...
