1、Designation:D662019Standard Practice forAsbestos Detection Limit Based on Counts1This standard is issued under the fixed designation D6620;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parenthe
2、ses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This practice presents the procedure for determining thedetection limit(DL)2for measurements of fibers or structures3using microscopy methods.1.2 This practi
3、ce applies to samples of air that are analyzedeither by phase contrast microscopy(PCM)or transmissionelectron microscopy(TEM),and samples of dust that areanalyzed by TEM.1.3 The microscopy methods entail counting asbestos struc-tures and reporting the results as structures per cubic centime-ter of a
4、ir(str/cc)or fibers per cubic centimeter of air(f/cc)forair samples and structures per square centimeter of surface area(str/cm2)for dust samples.1.4 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.5 This standard does not purp
5、ort to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.6 This international standard was
6、 developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Do
7、cuments2.1 ASTM Standards:4D1356 Terminology Relating to Sampling and Analysis ofAtmospheresD5755 Test Method for Microvacuum Sampling and IndirectAnalysis of Dust by Transmission Electron Microscopyfor Asbestos Structure Number Surface LoadingD6281 Test Method for Airborne Asbestos Concentration in
8、Ambient and Indoor Atmospheres as Determined byTransmission Electron Microscopy Direct Transfer(TEM)D6480 Test Method for Wipe Sampling of Surfaces,IndirectPreparation,and Analysis for Asbestos Structure NumberSurface Loading by Transmission Electron MicroscopyD7712 Terminology for Sampling and Anal
9、ysis of Asbestos3.Terminology3.1 Definitions:3.1.1 For terms not defined in this practice,see Terminolo-gies D1356 and D7712.3.2 Definitions of Terms Specific to This Standard:3.2.1 average,nthe sum of a set of measurements(counts)divided by the number of measurements in the set.3.2.1.1 DiscussionTh
10、e average is distinguished from themean.The average is calculated from data and serves as anestimate of the mean.The mean(also referred to as thepopulation mean,expected value,or first moment)is a param-eter of the underlying statistical distribution of counts.3.2.2 background,na statistical distrib
11、ution of structuresintroduced by(i)analyst counting errors and(ii)contaminationon an unused filter or contamination as a consequence of thesample collection and sample preparation steps.3.2.2.1 DiscussionThis definition of background is spe-cific to this practice.The only counting errors considered
12、inthis definition of background are errors that result in anover-count(that is,false positives).Analyst counting errors are1This practice is under the jurisdiction ofASTM Committee D22 on Air Qualityand is the direct responsibility of Subcommittee D22.07 on Sampling,Analysis,Management of Asbestos,a
13、nd Other Microscopic Particles.Current edition approved Jan.1,2019.Published January 2019.Originallyapproved in 2000.Last previous edition approved 2010 as D6620 06(2010).DOI:10.1520/D6620-19.2The DLalso is referred to in the scientific literature as limit of detection(LOD),method detection limit(MD
14、L),and other similar descriptive names.3For purposes of general exposition,the term“structures”will be used in placeof“fibers or structures.”In the examples in Section 8,the specific term,“fiber”or“structure,”is used where appropriate.These terms are defined separately in Section3.4For referenced AS
15、TM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA
16、19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.1 errors such as,determining the length of structures or fibersand whether,based on length,they should be counted;countingartifacts as fibers;determining the numb
