1、Designation: D 7201 06Standard Practice forSampling and Counting Airborne Fibers, Including AsbestosFibers, in the Workplace, by Phase Contrast Microscopy(with an Option of Transmission Electron Microscopy)1This standard is issued under the fixed designation D 7201; the number immediately following
2、the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice2describ
3、es the determination of the con-centration of fibers, expressed as the number of such fibers permillilitre of air, using phase contrast microscopy and optionallytransmission electron microscopy to evaluate particulate mate-rial collected on a membrane filter in the breathing zone of anindividual or
4、by area sampling in a specific location. Thispractice is based on the core procedures provided in theInternational Organization for Standardization (ISO) StandardISO 8672 (1)3, the National Institute for Occupational andHealth (NIOSH) Manual of Analytical Methods, NIOSH 7400(2), and the Occupational
5、 Safety and Health Administration(OSHA) Method ID 160 (3). This practice indicates the impor-tant points where these methods differ, and provides informa-tion regarding the differences, which will allow the user toselect the most appropriate procedure for a particular applica-tion. However, selectin
6、g portions of procedures from differentpublished methods generally requires a user to report that theyhave used a modification to a method rather than claim theyhave used the method as written.1.2 The practice is used for routine determination of anindex of occupational exposure to airborne fibers i
7、n work-places. Workplaces are considered those places where workersare exposed to airborne fibers including asbestos. Additionalinformation on sampling strategies, sample collection (includ-ing calibration) and use of sample results for asbestos abate-ment projects is provided in a standard Practice
8、 for AirMonitoring for Management of Asbestos-Containing Materials(WK 8951) currently being considered by ASTM subcommit-tee E06.24. A further practice has been approved for thespecific purpose of sampling and counting airborne fibers inmines and quarries (Practice D 7200), although the practicehere
9、in may also be used for this purpose. The current practicemay be used as a means of monitoring occupational exposureto asbestos fibers when asbestos fibers are known a priori to bepresent in the airborne dust. The practice gives an index ofairborne fiber concentration. This practice may be used inco
10、njunction with electron microscopy (See Appendix X1) forassistance in identification of fibers. This practice may be usedfor other materials such as fibrous glass, or man-made mineralfibers by using alternate counting rules (see Annex A4).1.3 This practice specifies the equipment and procedures fors
11、ampling the atmosphere in the breathing zone of an individualand for determining the number of fibers accumulated on afilter membrane during the course of an appropriately-selectedsampling period. The practice may also be used to sample theatmosphere in a specific location or room of a building (are
12、asampling), where this may be helpful in assessing exposure toworkers handling fiber-containing products.1.4 The ideal working range of this test practice extendsfrom 100 fibers/mm2to 1300 fibers/mm2of filter area. For a1000-L air sample, this corresponds to a concentration rangefrom approximately 0
13、.04 to 0.5 fiber/mL (or fiber/cm3). Lowerand higher ranges of fiber concentration can be measured byreducing or increasing the volume of air collected. However,when this practice is applied to sampling the presence of other,non-asbestos dust, the level of total suspended particulate mayimpose an upp
14、er limit to the volume of air that can be sampledif the filters produced are to be of appropriate fiber loading forfiber counting.1.5 Users should determine their own limit of detectionusing the procedure in Practice D 6620. For Reference theNIOSH 7400 method gives the limit of detection as 7 fibers
15、/mm2of filter area. For a 1000 L air sample, this corresponds toa limit of detection of 0.0027 fiber/mL (or fiber/cm3). ForOSHA method ID 160 the limit of detection is given as 5.5fibers/mm2of filter area. For a 1000 L air sample, thiscorresponds to a limit of detection of 0.0022 fiber/mL (orfiber/c
16、m3).1.6 If this practice yields a fiber concentration that does notexceed the occupational limit value for the particular regulatedfiber variety, no further action may be necessary. If the fiberconcentration exceeds the occupational limit value for aspecific fiber variety, and there is reason to sus
17、pect that the1This practice is under the jurisdiction ofASTM Committee D22 onAir Qualityand is the direct responsibility of Subcommittee D22.04 onWorkplaceAtmospheres.Current edition approved June 1, 2006. Published July 2006.2This test method is based on NIOSH 7400, OSHA Method ID 160, andISO 8672.
18、 Users of this ASTM standard are cautioned that if they wish to complywith one of these specific procedures exactly they should follow that procedure,otherwise they should document the modification3Boldface numbers in parentheses refer to the list of references appended to thismethod.1Copyright ASTM
19、 International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.specific fiber variety is mixed with other fibers not coveredunder the same standard or regulation, the optional methodspecified in Appendix X1 may be used to measure theconcentration or proportion of
20、 the fibers counted that are of theregulated variety.1.7 The mounting medium used in this practice has arefractive index of approximately 1.45. Fibers with refractiveindices in the range of 1.4 to 1.5 will exhibit reduced contrast,and may be difficult to detect.1.8 Fibers less than approximately 0.2
21、 m in diameter willnot be detected by this practice. (4)1.9 This standard may involve hazardous materials, opera-tions, and equipment. This standard does not purport toaddress all of the safety problems associated with its use. It isthe responsibility of the user of this standard to establishappropr
22、iate safety and health practices and determine theapplicability of regulatory limitations prior to use. For specificprecautionary statements, see Section 7.2. Referenced Documents2.1 ASTM Standards:4D 257 Test Methods for DC Resistance or Conductance ofInsulating MaterialsD 1356 Terminology Relating
23、 to Sampling and Analysis ofAtmospheresD 1357 Practice for Planning the Sampling of the AmbientAtmosphereD 3670 Guide for Determination of Precision and Bias ofMethods of Committee D22D 5337 Practice for Flow Rate Calibration of PersonalSampling PumpsD 6620 Practice for Asbestos Detection Limit Base
24、d onCountsD 7200 Practice for Sampling and Counting Airborne Fi-bers, IncludingAsbestos Fibers, in Mines and Quarries, byPhase Contrast Microscopy and Transmission ElectronMicroscopy2.2 Other StandardsNIOSH 7400 National Institute for Occupational Health andSafety (NIOSH), (Revised 1994)5Recommended
25、 Technical Method No.1 (RTM 1) AsbestosInternational Association (AIA)6ID 160 Occupational Safety and Health Administration(OSHA)ISO 8672 International Organization for Standardization(ISO)3. Terminology3.1 Description of terms specific to this practice, in additionto those found in Terminology D 13
26、56:3.1.1 asbestosa term applied to six specific silicate min-erals belonging to the serpentine and amphibole groups, whichhave crystallized in the asbestiform habit, causing them to beeasily separated into long, thin, flexible, strong fibers whencrushed or processed (5). The Chemical Abstracts Servi
27、ceRegistry Numbers of the most common asbestos varieties are:chrysotile (12001-29-5), riebeckite asbestos (crocidolite)(12001-28-4), grunerite asbestos (Amosite) (12172-73-5), an-thophyllite asbestos (77536-67-5), tremolite asbestos (77536-68-6) and actinolite asbestos (77536-66-4).The precise chemi
28、cal composition of each species varieswith the location from which it was mined. Other amphiboleminerals that exhibit the characteristics of asbestos have alsobeen observed (6).The nominal compositions of the most common asbestosvarieties are:Chrysotile Mg3Si2O5(OH)4Crocidolite Na2Fe32+Fe23+Si8O22(O
29、H)2Amosite (Mg,Fe)7Si8O22(OH)2Anthophyllite (Mg,Fe)7Si8O22(OH)2Tremolite Ca2(Mg,Fe)5Si8O22(OH)2(Mg/(Mg + Fe2+) 0.9 - 1.0)Actinolite Ca2(Mg,Fe)5Si8O22(OH)2(Mg/(Mg + Fe2+) 0.5 - 0.9)NOTE 1Actinolite compositions in which Mg/(Mg + Fe2+) is between0 and 0.5 are referred to as ferroactinolite. See Refere
30、nce (7) for the fullnaming conventions specified by the International Mineralogical Associa-tion.3.1.2 area samplean air sample collected so as to repre-sent the concentration of airborne dust in a specific area orroom, which, in the case of this practice, refers to an area orroom of a workplace.3.1
31、.3 asbestiforma specific type of fibrous mineral growthhabit in which the fibers and fibrils exhibit a polyfilamentousgrowth habit and possess high tensile strength and flexibility.All materials regulated as asbestos are asbestiform, but not allasbestiform minerals are classified as asbestos. Charac
32、teristicssuch as tensile strength and flexibility cannot be ascertainedfrom microscopic evaluation.3.1.4 asbestos fibera fiber of asbestos, which meets thecriteria specified below for a fiber. Phase Contrast Microscopy(PCM) does not identify fibers as asbestos. Under the lightmicroscope, a populatio
33、n of asbestos fibers may appear as amixture of fiber agglomerates, fiber bundles (polyfilamentousgrowth, unique to asbestiform fibers), fibers with split ends,and single fibers, the relative occurrence and frequency of eachtype depending on the situation.3.1.5 aspect ratiothe ratio of the length of
34、a fiber to itswidth.3.1.6 limit of detectionthe number of fibers necessary tobe 95 % confident that the result is greater than zero.3.1.7 differential countinga term applied to the practice ofexcluding certain kinds of fibers from the fiber count becausethey do not appear to be morphologically consi
35、stent with fibersof a specific variety thus modifying the definition of fiber givenbelow.3.1.8 fiberan elongated particle that is longer than 5.0 m,with a minimum aspect ratio of 3:1, and sometimes alsoclassified as having a maximum width of 3.0 m as this latterdimension may equate to the size of fi
36、ber, of the density ofmany silicate minerals, capable of penetrating to the lung. An4For referenced ASTM 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 p
37、age onthe ASTM website.5This standard is available from US Department of Health and Human Services,4676 Columbia Parkway, Cincinnati, OH 45226.6Available from Asbestos International Association, 68 Gloucester Place,London, W1H 3HL, EnglandD7201062asbestos fiber should further exhibit the asbestiform
38、 habit,although analysis of airborne fibers by PCM may not besufficient to determine asbestiform habit.3.1.9 fibrila single fiber of asbestos that cannot be furtherseparated longitudinally into smaller components without los-ing its fibrous properties or appearances.3.1.10 fibrousa habit of minerals
39、 composed of parallel,radiating, or interlaced aggregates of fibers, from which thefibers are sometimes separable. A crystalline aggregate may bereferred to as fibrous even if it is not composed of separablefibers, but has that distinct appearance. The term “fibrous” inmineralogy is used to describe
40、 aggregates of mineral grainsthat crystallize in a needle-like habit and appear to be com-posed of fibers. Asbestos minerals are fibrous, exhibiting aspecific type of fibrous habit termed asbestiform. However, notall minerals having fibrous habit are asbestos.3.1.11 field (of view)the area within a
41、graticule circle thatis superimposed on the microscope image.3.1.12 habitthe characteristic crystal growth form orcombination of these forms of a mineral, including character-istic irregularities.3.1.13 personal samplea sample taken by a collectionapparatus (membrane filter) positioned in the breath
42、ing zone ofthe subject (near the nose and mouth) such that the collectedparticles are representative of airborne dust that is likely toenter the respiratory system of the subject in the absence ofrespiratory protection.3.1.14 seta group of samples that are collected, submittedto the laboratory, and
43、analyzed for a report that is generated.3.1.15 Walton Beckett Graticulean eyepiece graticulespecifically designed for asbestos fiber counting. It consists ofa circle with a nominal projected diameter of 100 m (nominalarea of 0.00785 mm2) with a cross-hair having tick-marks at3-m intervals in one dir
44、ection and 5-m intervals in theorthogonal direction. There are also examples around theperiphery of the circle to illustrate specific sizes and shapes offibers. This design of the graticule is shown in Fig. A1.1. Thegraticule is placed in one of the microscope eyepieces so thatthe design is superimp
45、osed on the field of view.3.1.16 HSE/NPL7test slidea calibration slide designed todetermine the limit of visibility of a PCM and an observer.4. Summary of Practice4.1 The sample is collected by drawing air through a 25-mmdiameter, mixed cellulose ester (MCE) membrane filter, housedin a conductive po
46、lypropylene cassette. After sampling, asector of the membrane filter is converted to an opticallytransparent homogeneous gel. Fibers longer than 5 m arecounted by observing them with a PCM at a magnificationbetween 400 and 500.5. Significance and Use5.1 Users of this practice must determine for them
47、selveswhether the practices described meet the requirements of localor national authorities regulating asbestos or other fibroushazards.5.2 Variations of this practice have been described by theAsbestos Research Council in Great Britain (8), the AsbestosInternational Association (AIA) RTM 1 (9), NIO
48、SH 7400,OSHA (Reference Method ID 160), and ISO 8672. Where thecounting rules of the latter three methods differ, this is noted inthe text.5.3 Advantages5.3.1 The technique is specific for fibers. PCM is a fibercounting technique that excludes non-fibrous particles from theanalysis.5.3.2 The techniq
49、ue is inexpensive, but requires specializedknowledge to carry out the analysis for total fiber counts, atleast in so far as the analyst is often required under regulationsto have taken a specific training course (for example, NIOSH582, or equivalent).5.3.3 The analysis is quick and can be performed on-site forrapid determination of the concentrations of airborne fibers.5.4 Limitations5.4.1 The main limitation of PCM is that fibers are notidentified.All fibers within the specified dimensional range arecounted. Differential fiber counting may sometimes be used todi
