苏树春关于美国环保总署块状石棉鉴定的论文.ppt

Shu ChunSu Ph D SuScientificConsultingLtd BlossMineralogicalSessionGSAAnnualMeetingNovember4 2012Charlotte NC FundamentalFlawsofAHERATestMethodforDeterminingAsbestosConcentrationofBulkInsulationSamples November4 2012 2of40 Shu ChunSu M435 1985PassedbyUSCongresstoaddresstheasbestoshazardsinAmericanpublicschools1986SignedintolawbyReganThemagical1 wtACM AsbestosContainingMaterials asbestos 1 ToberemovedorcontainedNon ACM NonAsbestosContainingMaterials asbestos 1 NoactionisneededMandatestheuseofU S EPAInterimMethodfortheDeterminationofAsbestosinBulkInsulationSamples EPA600 M4 82 020 todeterminewhetherabulkinsulationsampleisACMorNon ACM1988NVLAP NationalVoluntaryLaboratoryAccreditationProgram BulkAsbestosAnalysisprogramwaslaunched TheAsbestosHazardEmergencyResponseAct AHERA November4 2012 3of40 Shu ChunSu M435 QualitativeanalysisPolarizedlightmicroscopyMorphologyColor PleochroismRefractiveIndicesParalleltofiberelongation n Perpendiculartofiberelongation n BirefringenceExtinctionElongationsignQuantitativeanalysisPointcountingStandardtechniqueinpetrographyfordeterminingtherelativeareaofoccupiedbyseparatemineralsinthinsectionsofrocksPrecisionandAccuracyNotavailableMarginofErrorsandConfidenceLevelsNotevenmentioned EPA600 M4 82 020Method November4 2012 4of40 Shu ChunSu M435 Thesadtruthis EPA600 M4 82 020Methodisincapableofdeliveringtheintendedresultsbecauseitsimplydoesn twork November4 2012 5of40 Shu ChunSu M435 AdministeredbyNVLAP NationalVoluntaryLaboratoryAccreditationProgram NIST NationalInstituteofStandardsandTechnology MonitoringtheperformanceofenvironmentallaboratoriesspecializedinasbestosanalysesTworoundsperyearFourbulksamplesperroundArea ofasbestoscomponentsisrequiredEPA600 M4 82 020MethodisusedThemostrigoroustestingprogramforbulkasbestosanalysisusingEPA600 M4 82 020Method NVLAPProficiencyTesting November4 2012 6of40 Shu ChunSu M435 AnalysisoftheresultsofPTsamplesfrom1993to1995 NVLAPProficiencyTestingResults November4 2012 7of40 Shu ChunSu M435 AnalysisoftheresultsofPTsamplesfrom2008to2011 NVLAPProficiencyTestingResults November4 2012 8of40 Shu ChunSu M435 Ofthe125PTsamplesfrom1993to2011RamificationsofFalseNegativeonpublicsafetyForANERAprojects areal lifeFNresultsmeansthathazardousschoolenvironmentsareconcludedtobesafeforstudentsandstaffRamificationsofFalsePositiveonpublicsafetyForANERAprojects areal lifeFPresultsmeansthattaxdollarsarewatedonunnecessaryasbestosabatement NVLAPProficiencyTestingResults November4 2012 9of40 Shu ChunSu M435 MostlaboratoriestreatedPTsampleswiththeutmostrespectMostlaboratoriesspentagreatdealoftimeoneachsampleMostlaboratoriesperformedthemoststringentqualityassuranceanalysisonPTsamplesThePTresultsrepresentthehighestlevelofproficiencyoftheeliteenvironmentallaboratoriesintheUSandtheworldWhatwouldhavebeentheerrorratesofroutinebulksampleanalysescosting 5orevenless RamificationsofhighpercentagesofFNandFGonthevalidityofEPA600 M4 82 020MethodIt squantificationproceduredoesn twork NVLAPProficiencyTestingResults November4 2012 10of40 Shu ChunSu M435 ParameterstobeanalyzedisnotwhatisrequiredbyAHERAArea issignificantlydifferentfromwt becauseofthesignificantdensitydifferencesbetweenasbestosmineralsandmatrixmaterialsinbulkinsulationandbuildingsamplesPointcountingisextremelyinadequateforbulksamplescomposedofasbestosfiberslooselydistributedamongparticularand orfibrousmatrixparticlesItwasdesignedforrockthinsectionswithuniformthicknessofallcomponents400pointisdrasticallyinsufficientforthemajorityofbulksamplesPrecisionandaccuracyarenotdefinedMarginoferrorsandconfidencelevelsarenotdefined FundamentalFlawsofEPA600 M4 82 020Method November4 2012 11of40 Shu ChunSu M435 1985PassedbyUSCongresstoaddresstheasbestoshazardsinAmericanpublicschools1986SignedintolawbyReganThemagical1 wtACM AsbestosContainingMaterials asbestos 1 Abatementetc Non ACM NonAsbestosContainingMaterials asbestos 1 Abatementetc mandatestheuseofU S EnvironmentalProtectionAgency EPA InterimMethodfortheDeterminationofAsbestosinBulkInsulationSamples EPA600 M4 82 020 todeterminewhetherabulkinsulationsampleisasbestos containingmaterial1988NVLAPBulkAsbestosAnalysisprogramlaunched TheAsbestosHazardEmergencyResponseAct AHERA November4 2012 12of40 Shu ChunSu M435 Issue1 Parametertobedetermined November4 2012 13of40 Shu ChunSu M435 ThisparametermustbeaconstantpropertyoftheoriginalsampleAsbestosNumber RatioofAsbestos AllParticles isNOTweight orvolume orarea ISThisparametermustnotbechangedbythesamplepreparationprocessAsbestosNumber RatioofAsbestos AllParticles isNOTweight orvolume ISThisparametermustnotbechangedbythesub samplesampling e g theparticlesizerangetobeanalyzedAsbestosNumber RatioofAsbestos AllParticles isNOTweight orvolume orarea MAYBEifthepreparedsampleisthoroughlyhomogenized PrinciplesforSelectingtheParametertobeDetermined November4 2012 14of40 Shu ChunSu M435 ThisparameterisnotaconstantpropertyoftheoriginalserpentineaggregateWedon tknowthenumberofasbestosparticlesintheoriginalsampleWedon tknowthenumberofnon asbestosparticlesintheoriginalsampleWecanspikeasamplewithaknownwt e g 0 5wt ofasbestosWecannotcreateasamplewithaknownAsbestosNumber Asamplespikedwith0 5wt ofasbestosdoesnotnecessarilyandmostunlikelyhas0 5number ofasbestosnotonlyintheoriginalbutalsointhepreparedsamplesThisparameterchangeswithsamplepreparationprocess crushing pulverization sieving etc Boththenumerator thenumberofasbestosparticles anddenominator thenumberofnon asbestosparticles arechangedbythesamplepreparationprocessinanon controllablewayThisparameterchangeswiththesub samplesamplingprocessWedon tknowandcan tcontrolPSDofasbestosparticlesinthepreparedsampleWedon tknowandcan tcontrolPSDofnon asbestosparticlesinthepreparedsampleAsbestosNumber isnotaconstantthroughouttheparticlesizerange AsbestosNumber RatioofAsbestos AllParticleNumbers November4 2012 15of40 Shu ChunSu M435 Ifthesameoriginalserpentineaggregatesampleisprepared10timeswithexactlythesameprocedurebythesamelaboratory theresulted10preparedsampleswillstillhavedifferenttotalnumberofasbestosparticlesdifferenttotalnumberofnon asbestosparticlesdifferentPSDofasbestosparticlesdifferentPSDofnon asbestosparticlesdifferentAsbestosNumber orRatioofAsbestos AllParticleNumbersindifferentparticlesizerangesTheabovefactswillmakeitimpossibletoattainreproducibleAsbestosNumber resultsinILS InterlaboratoryStudy AsbestosNumber isNOTaSuitableParametertobeAnalyzed November4 2012 16of40 Shu ChunSu M435 Theviableoptionsarelimitedwt volume orarea Asbestoswt seemstobetheonlyalternativeItisaCONSTANTpropertyoftheoriginalserpentineaggregateItdoesNOTchangewithsamplepreparationprocess crushing pulverization sieving etc Ifproperhomogenizationmeasureistaken itschangewiththesub samplesamplingcanbereasonablyminimized IfNOTAsbestosNumber WhatistheAlternative November4 2012 17of40 Shu ChunSu M435 Issue2 AmountofSampletobeAnalyzed November4 2012 18of40 Shu ChunSu M435 Whythisisanissue Ifinsufficientamountofsampleisanalyzed theanalyzedportionofsamplemayNOTcontainanyasbestosTheanalyzedsub sampleshouldcontainatleastONEasbestosparticleHowtodeterminetheminimumamountofsampletobeanalyzedtofindatleastoneasbestosfiber Assumingtheaverageweightofasingleasbestosparticleis0 1mgAssumingtheasbestos ofthesampleis0 25wt AssumingthepreparedsampleisperfectlyhomogeneousTheminimumamountofsamplecontainingatleastONEasbestosparticleis 0 1mg 0 25 40mg HowMuchSampleShouldbeAnalyzedtoFindAtLeastOneAsbestosFiber November4 2012 19of40 Shu ChunSu M435 TEManalystmustfirstcalculatethenumberofgridopenings orthesummedfilterarea tobeanalyzedtomeettherequiredAS AnalyticalSensitivity beforecommencinganalysisAHERAprotocol AS 0 005structure cm3DefinitionofASforAirborneAsbestosAnalysistheairborneasbestosconcentrationrepresentedbyONEasbestosstructurefoundintheanalyzedareaofaTEMgrid AnalyticalSensitivityforAirborneAsbestosAnalysis November4 2012 20of40 Shu ChunSu M435 DefinitionofASforBulkAsbestosAnalysistheasbestosconcentrationrepresentedbyONEasbestosstructurefoundintheamountofsampleanalyzedortheweightpercentageofasingleasbestosstructureintheamountofsampleanalyzedExample Assumingtheamountofsampleanalyzedis20mgIftheaverageweightofasingleasbestosis0 2mg AS 0 2 20 1wt Iftheaverageweightofasingleasbestosis0 05mg AS 0 05 20 0 25wt OncewesetanASandknowtheaverageweightofasingleasbestosstructure wecancalculatetheminimumamountofsampletobeanalyzedIfASissettobe0 25wt andtheaverageweightofasingleasbestosstructureis0 1mg theminimumamountofsampletobeanalyzed 0 1mg 0 25 40mg AnalyticalSensitivityforBulkAsbestosAnalysis November4 2012 21of40 Shu ChunSu M435 Thefollowingamphibolefiberweighs0 0155mgWidth 0 1mmor100mmHeight 0 1mmor100mmAspectratio 5 1Length 0 5mmor500mmAverageDensity 3 1mg mm3ToattainAS 0 25wt Atminimum 6 2mgsampleshouldbeanalyzed HowMuchaSingleAsbestosFiberWeighs L H W November4 2012 22of40 Shu ChunSu M435 AnFOV fieldofview containsapprox 0 013mgofsamplematerial assumingthefollowingOlympusBH 2PLM10 xobjectiveFOVDiameter 2mmSlidecoverage 60 Coverslip 22mmsquareTotalsampleweightonslide 3mg HowMuchSampleinaSingleFOVWeighs Chalkley25pointarray November4 2012 23of40 Shu ChunSu M435 EquationforCalculatingAS whereAS analyticalsensitivityWA theaverageweightasingleasbestosstructureWS thetotalweightofsampleanalyzedNFOV thenumberofFOVanalyzedWFOV theaveragesampleweightinasingleFOVD theaveragedensityofasbestosfibers mg mm3 T theaveragethicknessandwidthofasbestosfiber mm AR theaverageaspectratioofasbestosfibers November4 2012 24of40 Shu ChunSu M435 EquationforCalculatingNFOV whereAS thepresetanalyticalsensitivity WA theaverageweightasingleasbestosstructureWS thetotalweightofsampleanalyzedNFOV thenumberofFOVtobeanalyzedtoattainASWFOV theaveragesampleweightinasingleFOVD theaveragedensityofasbestosfibers mg mm3 T theaveragethicknessandwidthofasbestosfiber mm AR theaverageaspectratioofasbestosfibers November4 2012 25of40 Shu ChunSu M435 ASvs NFOVforAmphiboles November4 2012 26of40 Shu ChunSu M435 Itisnotadvisabletofollowthe one size fits all pointcountingguidelineofEPA600 M4 82 020 1982 bulkasbestosanalyticalprotocoltocount400non emptypointsregardlessoftheaverageparticlesizeofasbestosfibersIfthe25 pointChalkleypointarrayisused 400non emptypointsaccountforonly8orslightlymoreFOV s theuseofChalkleypointarrayshouldbeabandonedandscanusingamechanicalstageandacross hairocularshouldbeadopted tobediscussedlater Iftheaveragethickness widthofamphibolefibersis200mm andtheaverageaspectratiois3 1 atminimum1 528FOV sor10slidesaretobeanalyzedtoattainanASof0 25wt Inotherwords ifthesampletobeanalyzedcontains0 25wt amphibolefibersoftheaboveaveragesize atminimum1 528FOV sor10slideswillhavetobecounted scannedtofindONEamphibolefiber ImplicationsofASvs NFOVRelationship November4 2012 27of40 Shu ChunSu M435 Issue3 NumberofPointstobecounted November4 2012 28of40 Shu ChunSu M435 Whythisisanissue Ifinsufficientnumberofpointiscounted thecountedpointsmayNOTcontainanyasbestospointInotherwords thetotalnumberofpointcountedshouldcontainatleastONEasbestospointThe400non emptypointsguidelineofEPA600 M4 82 020 1982 bulkasbestosanalyticalprotocolhasNOscientificconnotationHowtodeterminetheminimumnumberofPTBC pointstobecounted Statisticalanalysis HowManyPointShouldbeCounted November4 2012 29of40 Shu ChunSu M435 Asbestosandnon asbestosparticlecountingcanbeviewedasatwo colorballsproblemusedbystatisticianstoteachprobabilityAsbestosparticles BlackballsNon asbestosparticles WhiteballsTheserpentineaggregatesamples bagsofmixedBlackandWhiteballswithsamediameterandweight sothatfollowingdiscussionsapplyequallytonumber wt area etc Determiningifamphiboleinaserpentineaggregatesampleis 0 25wt canbesimplifiedtodeterminingifabagofinfinitenumberofmixedBlackandWhiteballscontains 0 25 ofBlackballsbysamplingandcountingafinitenumberofballs aproblemthatcanbeeasilysolvedbyelementaryprobabilityandstatistics TheSimplestStatisticalModel BackandWhiteBallsModel November4 2012 30of40 Shu ChunSu M435 EstimatethepercentageofBlackballsinapopulationofmixedBlackandWhiteballsB thenumberofBlackballsinasampleW thenumberofWhiteballsinasampleBlackandWhiteballshavethesamediameter densityandweightThetotalnumberof B W issolargethatthepopulationcanbeconsideredtobeinfiniteDrawingnballsfromthepopulationandcountingBandWtoobtainx B 100 B B W ThisisatypicalBinomialDistributionproblem Whenthesamplesizenislargeenough itcanbeapproximatedbyNormalDistributionEstimatethepercentageofBlackballsinapopulationofmixedBlackandWhiteballsB thenumberofBlackballsinasampleW thenumberofWhiteballsinasample BackandWhiteBallsModel November4 2012 31of40 Shu ChunSu M435 EquationforCalculatingSampleSize wheren samplesizethatislargeenoughtoattainthespecifiedmaximumallowederrorandconfidencelevelp aroughestimateofpopulationproportion B E MAE maximumallowederror z criticalvaluefromnormaldistributioncorrespondingtothespecifiedconfidencelevelz 1 96for95 confidencelevelz 2 575for99 confidencelevel Nate 1 Givenzandp thisequationcanbeusedtocalculatethemarginoferrorassociatedwithaspecificn2 Thederivationofthisequationisomittedinthispresentation whichcanbefoundingeneralprobability statisticstexts November4 2012 32of40 Shu ChunSu M435 SampleSize PointstoBeCounted toAttainSpecifiedMAEandCLatDifferentp Forexample ifasbestos is0 25 andthemarginoferrorissetat0 10 atminimum9 580pointsaretobecountedtoattain95 CL Inotherwords ifthesampleisrepeatedlyanalyzed100timesitisexpectedthattheresultedasbestos iswithin0 15 0 35 95times November4 2012 33of40 Shu ChunSu M435 HowManyPointShouldbeCounted AssumingAmphiboleparticlesandnon asbestosparticlesareperfectsphereswiththesamediameteranddensityThesampleisideallyhomogeneousTheamphiboleconcentrationlevelisapprox 0 25wt ConfidencelevelCLissetat95 Atminimum1 533pointswillhavetobecountedtoensuretheresultedAmphibolewt isaccuratewithin 0 25 Atminimum9 580pointswillhavetobecountedtoensuretheresultedAmphibolewt isaccuratewithin 0 10 Atminimum38 320pointswillhavetobecountedtoensuretheresultedAmphibolewt isaccuratewithin 0 05 November4 2012 34of40 Shu ChunSu M435 AnotherUseoftheSampleSizeTable Giventhepointscountedandthemeasuredasbestos themarginoferrorcanbecalculatedforaspecifiedCLfordifferentpasfollows Forexample if400pointsarecountedandtheresultis0 25 themarginoferroris0 49 Inotherwords ifthesampleisrepeatedlyanalyzed100timesitisexpectedthattheresultedasbestos iswithin0 0 74 95times November4 2012 35of40 Shu ChunSu M435 IfSoManyParticlesHavetobeCounted AreThereLessStrenuousAlternatives TheanswerisgenerallyNO However insomecases especiallywhenproperstoppingrulesare tobediscussedlater applied 400pointswillbesufficientTheproblemwearefacingisaclassiconeaboutestimatingthepopulationproportionfromsampleproportionmeasuredfromasinglemeasurement Thistypeofmeasurementresultsisusuallyusedtomakedecisionwhethercertainactionsshouldbetakenornot Therefore theprobabilityofmakingFalsePositiveorFalseNegativeerrors theso calledTypeIandTypeIIerrorsinstatistics isofparamountimportancefordecisionmakers Confidencelevelandmarginoferroraretwofactorsthathavetobetakenintoaccount whicharedirectlycontrolledbythesamplesize The one size fits all approachimpliedbythe400non emptypointsguidelineofEPA600 M4 82 020 1982 wasnotbackedbystatisticalanalysisTosummarize firstdecidehowaccurate marginoferror andhowreliable confidencelevel themeasurementresultsshouldbethencalculatetheminimumnumberofpointstobecountedtoattainthespecifiedaccuracyandreliability November4 2012 36of40 Shu ChunSu M435 RecommendedStatisticalApproach HypothesisTesting BecauseAirborneToxicControlMeasuredefinesthataggregatematerial sasbestoscontentlimitis 0 25 theregulator sinterestisnotnecessarilytheexactasbestos inaggregatematerialbutwhetherthematerialinquestioncontains 0 25 ofasbestosHypothesistestingforpopulationproportion anotherpopularstatistictool seemstobetheidealapproachforthisproblem November4 2012 37of40 Shu ChunSu M435 HypothesisTesting UsuallythepurposeofastatisticalHT hypothesistesting istorejectthenullhypothesisandprovethatthealternativehypothesisistrue Whenthisoccurs onecanbecertainthattheprobabilityofmakingaFalsePositiveconclusion TypeIError isonly5 at95 confidencelevelWhenacceptinganullhypothesis youhavetoworryaboutacceptingaFalseNegative ThisiscallTypeIIError orberror ItisusuallydifficulttoevaluatetheprobabilityofmakingTypeIIError Sostatisticiansusuallydon tacceptnullhypothesis November4 2012 38of40 Shu ChunSu M435 HypothesisTestingforM435 Nullhypothesis H0 assumingp0 0 25wt Theamphiboleconcentrationis p0or 0 25wt Thealternativehypothesis H1 Theasbestosconcentrationis p0or 0 25wt IfCLissetat95 or99 theprobabilityofmakingaTypeIerror FalsePositive shouldbe5 or1 respectivelyOnlyifwearemoreconcernedaboutthemakingaTypeIIerror FalseNegative theaboveNullandAlternativehypothesesshouldbereversed However thisisnotadvisableforM435 November4 2012 39of40 Shu ChunSu M435 HypothesisTestingforM435 Countnpointsofasbestosandnon asbestosRecordthenumberofAsbestospointsasxCalculateAsbestosconcentrationasp x nCalculatethez teststatisticszcalcComparezcalcwithz0 Ifzcalc 1 96 z0atCL 95 orzcalc 2 58 z0atCL 99 REJECTH0andconcludethatamphibole ofsample 0 25wt Ifzcalc 1 96 z0atCL 95 orzcalc 2 58 z0atCL 99 ACCEPTH0andconcludethatamphibole ofsample 0 25wt November4 2012 40of40 Shu ChunSu M435 DeterminationofStoppingRules xcriticalisthexvalueforzcalc z0atthespecifiedCL MAEandn Roundupxcriticaltointegertogetxstop thesmallestxvaluetorejectH0 intherightmostcolumnofthefollowingtable Forexample ifCL 95 andn 1 533 theanalysiscanbestoppedatthe8thasbestospoint atwhichH0isrejected Additionalasbestospointwillnotchangethisconclusion November4 2012 41of40 Shu ChunSu M435 AnalyticalProceduresofHypothesisTestingforM435 Prepareafew atleast5 slidesandscanthemtogettheaveragewidthandaspectratioofamphibolefibers Forexample width 200mmandAR 3 1SetuptheanalyticalparametersasfollowsPreparethenumberofslidesasindicatedintheabovetable IfnoasbestosfiberhasbeenidentifiedduringthevisualscanofStep1 prepare10slidesandvisuallyscanallofthemtoensurethatthereisnoasbestosfiberspresentbeforestoppingtheanalysisandreportingAsbestoswt N D notdetected November4 2012 42of40 Shu Chu