1.1本惯例 2. 描述了使用相衬显微镜和可选的透射电子显微镜来评估在个人呼吸区的膜过滤器上收集的颗粒材料，或通过在特定位置的区域采样来确定纤维浓度，以每毫升空气中此类纤维的数量表示。本实践基于国际标准化组织（ISO）标准ISO中提供的核心程序 8672 ( 1. ) 3. ，美国国家职业健康研究所（NIOSH）分析方法手册，NIOSH 7400 ( 2. )，以及职业安全与健康管理局（OSHA）方法ID 160 ( 3. ). 本规程指出了这些方法不同的要点，并提供了有关差异的信息。然而，从不同发布的方法中选择部分过程通常需要用户报告他们使用了对方法的修改，而不是声称他们使用了书面方法。本规程进一步指导了如何使用差分计数技术来指示石棉纤维种群的位置。 1.2本规程用于常规测定矿山、采石场或其他可能加工或处理矿石的地点的空气纤维职业暴露指数。该方法给出了空气中纤维浓度的指标。该方法提供了可能是石棉的计数纤维分数的估计值。本规程应与电子显微镜一起使用（参见 附录X1 )以帮助识别纤维。 1.3本实施规程规定了对个人呼吸区内的大气进行采样的设备和程序，以及在适当的操作过程中确定滤膜上累积的纤维数量的设备和程序- 选定的采样周期。该方法也可用于在矿井或建筑物房间的特定位置对大气进行采样（区域采样）。 1.4本规程的理想工作范围为100纤维/毫米 2. 至1300根纤维/毫米 2. 过滤面积的。对于1000升空气样品，这对应于约0.04至0.5纤维/毫升（或纤维/厘米）的浓度范围 3. ). 通过减少或增加收集的空气量，可以测量纤维浓度的高低范围。然而，当这种做法适用于矿山和采石场的个人采样时，如果所生产的过滤器具有适当的颗粒负载以进行纤维计数，则总悬浮颗粒物的水平可能会对可采样的空气体积施加上限。 1.5用户应在实践中使用该程序确定自己的检测极限 D6620 . 作为参考，NIOSH 7400 该方法的检测极限为7纤维/毫米 2. 过滤面积的。对于1000-L空气样品，这对应于0.0027纤维/毫升（或纤维/厘米）的检测极限 3. ). 对于OSHA ID 160 检测极限为5.5纤维/毫米 2. 过滤面积的。对于1000-L空气样品，这对应于0.0022纤维/毫升（或纤维/厘米）的检测极限 3. ). 1.6如果本规程产生的纤维浓度不超过特定调节纤维品种的允许暴露极限或阈值的一半，则无需采取进一步措施。 如果纤维浓度超过特定规定纤维品种的规定允许暴露极限或阈值的一半，则有必要检查数据，以确定超过50%的计数纤维是否小于1.0μm或更厚，但具有石棉外观（弯曲、八字端或束状外观）。 1.7本规程中使用的安装介质的折射率约为1.45。折射率在1.4到1.5之间的光纤对比度会降低，可能难以检测。 1.8本规程可能无法检测到直径小于约0.2µm的纤维。( 4. ) 1.9 本标准可能涉及危险材料、操作和设备。本标准并非旨在解决与其使用相关的所有安全问题。本标准的用户有责任在使用前制定适当的安全和健康实践，并确定监管限制的适用性。有关具体的预防说明，请参阅第节 7. . ====意义和用途====== 5.1本规程的使用者必须自行确定所述规程是否符合当地或国家主管部门对石棉或其他纤维危害进行监管的要求。 5.2英国石棉研究委员会描述了这种做法的变化( 8. )，石棉国际协会（AIA）（RTM 1） ( 9 )，NIOSH 7400 ，OSHA（参考方法ID 160 )，和ISO 8672 . 如果这些方法的计数规则不同，则在本文中予以说明。 5.3 优势 5.3.1该技术针对纤维。PCM是一种纤维计数技术，从分析中排除非纤维颗粒。 5.3.2该技术价格低廉，但需要专业知识来进行总纤维数分析，至少在法规要求分析员经常参加特定培训课程（例如NIOSH 582或同等课程）的情况下是如此。 5.3.3分析快速，可在现场进行，以快速测定空气中纤维的浓度。 5.3.4该程序提供了一种判别计数技术，可用于估计可能为石棉的已计数纤维的百分比。 5.4 局限性 5.4.1 PCM的主要限制是未识别光纤。计算指定尺寸范围内的所有纤维。有时可以使用差异纤维计数来区分石棉纤维和形态明显不同的纤维，如纤维素和玻璃纤维。 在大多数情况下，如果没有额外的阳性识别，则无法使用差异纤维计数来充分区分石棉和非石棉纤维，以符合法规。如果需要对石棉进行阳性识别，则必须通过偏振光或电子显微镜技术，使用过滤器的不同部分进行。 5.4.2另一个限制是，PCM可见的最小纤维直径约为0.2µm，而最细的石棉纤维直径可能小至0.02µm。 5.4.3如果纤维浓度的计算结果超过监管标准，则非- 除非可以证明计数的纤维不属于该标准规定的纤维组的一个或多个成员，否则假设符合性。

1.1 This practice 2 describes the determination of the concentration of fibers, expressed as the number of such fibers per millilitre of air, using phase contrast microscopy and optionally transmission electron microscopy to evaluate particulate material collected on a membrane filter in the breathing zone of an individual or by area sampling in a specific location. This practice is based on the core procedures provided in the International Organization for Standardization (ISO) Standard ISO 8672 ( 1 ) 3 , the National Institute for Occupational and Health (NIOSH) Manual of Analytical Methods, NIOSH 7400 ( 2 ), and the Occupational Safety and Health Administration (OSHA) Method ID 160 ( 3 ). This practice indicates the important points where these methods differ, and provides information regarding the differences. However, selecting portions of procedures from different published methods generally requires a user to report that they have used a modification to a method rather than claim they have used the method as written. This practice further gives guidance on how differential counting techniques may be used to indicate where a population of fibers may be asbestos. 1.2 The practice is used for routine determination of an index of occupational exposure to airborne fibers in mines, quarries, or other locations where ore may be processed or handled. The method gives an index of airborne fiber concentration. The method provides an estimate of the fraction of counted fibers that may be asbestos. This practice should be used in conjunction with electron microscopy (See Appendix X1 ) for assistance in identification of fibers. 1.3 This practice specifies the equipment and procedures for sampling the atmosphere in the breathing zone of an individual and for determining the number of fibers accumulated on a filter membrane during the course of an appropriately-selected sampling period. The method may also be used to sample the atmosphere in a specific location in a mine or in a room of a building (area sampling). 1.4 The ideal working range of this practice extends from 100 fibers/mm 2 to 1300 fibers/mm 2 of filter area. For a 1000-L air sample, this corresponds to a concentration range from approximately 0.04 to 0.5 fiber/mL (or fiber/cm 3 ). Lower and higher ranges of fiber concentration can be measured by reducing or increasing the volume of air collected. However, when this practice is applied to personal sampling in mines and quarries, the level of total suspended particulate may impose an upper limit to the volume of air that can be sampled if the filters produced are to be of appropriate particulate loading for fiber counting. 1.5 Users should determine their own limit of detection using the procedure in Practice D6620 . For reference, the NIOSH 7400 method gives the limit of detection as 7 fibers/mm 2 of filter area. For a 1000-L air sample, this corresponds to a limit of detection of 0.0027 fiber/mL (or fiber/cm 3 ). For OSHA ID 160 the limit of detection is given as 5.5 fibers/mm 2 of filter area. For a 1000-L air sample, this corresponds to a limit of detection of 0.0022 fiber/mL (or fiber/cm 3 ). 1.6 If this practice yields a fiber concentration that does not exceed one-half the permissible exposure limit or threshold limit value for the particular regulated fiber variety, no further action may be necessary. If the fiber concentration exceeds one-half of the regulated permissible exposure limit or threshold limit value for the particular regulated fiber variety, it is necessary to examine the data to determine if more than 50 % of the counted fibers are thinner than 1.0 μm, or thicker but with an appearance of asbestos (curvature, splayed ends, or the appearance of a bundle). 1.7 The mounting medium used in this practice has a refractive index of approximately 1.45. Fibers with refractive indices 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 µm in diameter may not be detected by this practice. ( 4 ) 1.9 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific precautionary statements, see Section 7 . ====== Significance And Use ====== 5.1 Users of this practice must determine for themselves whether the practices described meet the requirements of local or national authorities regulating asbestos or other fibrous hazards. 5.2 Variations of this practice have been described by the Asbestos Research Council in Great Britain ( 8 ), the Asbestos International Association (AIA) (RTM 1) ( 9 ), NIOSH 7400 , OSHA (Reference Method ID 160 ), and ISO 8672 . Where the counting rules of these methods differ, this is noted in the text. 5.3 Advantages 5.3.1 The technique is specific for fibers. PCM is a fiber counting technique that excludes non-fibrous particles from the analysis. 5.3.2 The technique is inexpensive, but requires specialized knowledge to carry out the analysis for total fiber counts, at least in so far as the analyst is often required under regulations to have taken a specific training course (for example, NIOSH 582, or equivalent). 5.3.3 The analysis is quick and can be performed on-site for rapid determination of the concentrations of airborne fibers. 5.3.4 The procedure provides for a discriminate counting technique that can be used to estimate the percentage of counted fibers that may be asbestos. 5.4 Limitations 5.4.1 The main limitation of PCM is that fibers are not identified. All fibers within the specified dimensional range are counted. Differential fiber counting may sometimes be used to discriminate between asbestos fibers and fibers of obviously different morphology, such as cellulose and glass fiber. In most situations, differential fiber counting cannot be used to adequately differentiate asbestos from non-asbestos fibers for purposes of compliance with regulations without additional positive identification. If positive identification of asbestos is required, this must be performed by polarized light or electron microscopy techniques, using a different portion of the filter. 5.4.2 A further limitation is that the smallest fibers visible by PCM are about 0.2 µm in diameter, while the finest asbestos fibers may be as small as 0.02 µm in diameter. 5.4.3 Where calculation of fiber concentration provides a result exceeding the regulatory standard, non-compliance is assumed unless it can be proven that the fibers counted do not belong to a member or members of the group of fibers regulated by that standard.