1.1 此测试方法 2. 是一种使用透射电子显微镜（TEM）测定环境大气中石棉结构浓度的分析程序，包括测量结构的尺寸和在计算纵横比的结构中发现的石棉纤维的尺寸。 1.1.1 该试验方法允许测定存在的石棉纤维的类型。 1.1.2 该试验方法不能总是区分同一种角闪石矿物的石棉和非石棉类似物的单个纤维。 1.2 该试验方法适用于环境（室外）和建筑大气中石棉的测定。 1.2.1 该试验方法适用于吸入已知体积空气的聚碳酸酯毛细管孔过滤器或纤维素酯（纤维素或硝酸纤维素的混合酯）过滤器和空白过滤器。 1.3 该试验方法可确定的浓度上限为7000 s/mm 2. 由该值表示的空气浓度是采样空气体积的函数。 1.3.1 可以检测到的石棉纤维的尺寸没有下限。在实践中，显微镜检查非常小的石棉纤维的能力各不相同。因此，0.5μm的最小长度被定义为报告结果中包含的最短纤维。 1.4 如果分析的样品收集过滤器的一般颗粒物负载超过约10，则不能使用直接分析方法 % 颗粒物对收集过滤器的覆盖。 1.5 以国际单位制表示的数值应视为标准。本标准中不包括其他计量单位。 1.6 本标准并非旨在解决与其使用相关的所有安全问题（如有）。 本标准的使用者有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.7 本国际标准是根据世界贸易组织技术性贸易壁垒委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认的标准化原则制定的。 ===意义和用途====== 5.1 本试验方法适用于在各种环境空气情况下测量空气中的石棉，并对石棉结构的任何大气进行详细评估。环境大气中的大多数纤维都不是石棉，因此需要对纤维进行鉴定。 环境大气中的大多数空气中的石棉纤维的直径都低于光学显微镜的分辨率极限。该测试方法基于透射电子显微镜，其分辨率足以检测细小的细纤维，是目前唯一能够明确识别大多数石棉单个纤维的技术。石棉通常不是以单一纤维的形式存在，而是以非常复杂的聚集结构存在，这些结构可能也可能不与其他颗粒聚集。如果花费足够的测量努力，通常可以明确地识别悬浮在环境大气中的纤维。然而，如果以这种方式识别每种纤维，分析将变得昂贵得令人望而却步。由于仪器的缺陷或颗粒物的性质，一些纤维不能被确定为石棉，尽管测量结果都表明它们可能是石棉。 因此，主观因素有助于这种测量，因此，需要对石棉纤维的识别和计数程序进行非常精确的定义。本试验方法中定义的方法旨在描述空气样本中发现的含石棉颗粒的性质、数值浓度和尺寸。测试方法必然是复杂的，因为观察到的结构往往非常复杂。测试方法中规定的数据记录方法旨在允许在开发新的测量应用程序时重新评估结构计数数据。所有可行的样品制备技术都会对空气中的颗粒物进行一些改性。甚至从三维空气传播到两个- 尺寸过滤器表面可以被认为是颗粒物质的改性，在大多数样品中，一些颗粒通过样品制备程序进行了改性。然而，本试验方法中规定的程序旨在最大限度地减少对收集颗粒材料的干扰。 5.2 该测试方法适用于单个滤波器的分析，并描述了单个滤波器测量的精度（见 13.1 )。通常需要多个空气样本来表征空气中石棉在时间和空间上的浓度。为此目的所需的样本数量与样本之间的测量变化成比例，该变化可能大于单个样本的测量变化。

1.1 This test method 2 is an analytical procedure using transmission electron microscopy (TEM) for the determination of the concentration of asbestos structures in ambient atmospheres and includes measurement of the dimension of structures and of the asbestos fibers found in the structures from which aspect ratios are calculated. 1.1.1 This test method allows determination of the type(s) of asbestos fibers present. 1.1.2 This test method cannot always discriminate between individual fibers of the asbestos and non-asbestos analogues of the same amphibole mineral. 1.2 This test method is suitable for determination of asbestos in both ambient (outdoor) and building atmospheres. 1.2.1 This test method is defined for polycarbonate capillary-pore filters or cellulose ester (either mixed esters of cellulose or cellulose nitrate) filters through which a known volume of air has been drawn and for blank filters. 1.3 The upper range of concentrations that can be determined by this test method is 7000 s/mm 2 . The air concentration represented by this value is a function of the volume of air sampled. 1.3.1 There is no lower limit to the dimensions of asbestos fibers that can be detected. In practice, microscopists vary in their ability to detect very small asbestos fibers. Therefore, a minimum length of 0.5 μm has been defined as the shortest fiber to be incorporated in the reported results. 1.4 The direct analytical method cannot be used if the general particulate matter loading of the sample collection filter as analyzed exceeds approximately 10 % coverage of the collection filter by particulate matter. 1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 5.1 This test method is applicable to the measurement of airborne asbestos in a wide range of ambient air situations and for detailed evaluation of any atmosphere for asbestos structures. Most fibers in ambient atmospheres are not asbestos, and therefore, there is a requirement for fibers to be identified. Most of the airborne asbestos fibers in ambient atmospheres have diameters below the resolution limit of the light microscope. This test method is based on transmission electron microscopy, which has adequate resolution to allow detection of small thin fibers and is currently the only technique capable of unequivocal identification of the majority of individual fibers of asbestos. Asbestos is often found, not as single fibers, but as very complex, aggregated structures, which may or may not also be aggregated with other particles. The fibers found suspended in an ambient atmosphere can often be identified unequivocally if sufficient measurement effort is expended. However, if each fiber were to be identified in this way, the analysis would become prohibitively expensive. Because of instrumental deficiencies or because of the nature of the particulate matter, some fibers cannot be positively identified as asbestos even though the measurements all indicate that they could be asbestos. Therefore, subjective factors contribute to this measurement, and consequently, a very precise definition of the procedure for identification and enumeration of asbestos fibers is required. The method defined in this test method is designed to provide a description of the nature, numerical concentration, and sizes of asbestos-containing particles found in an air sample. The test method is necessarily complex because the structures observed are frequently very complex. The method of data recording specified in the test method is designed to allow reevaluation of the structure-counting data as new applications for measurements are developed. All of the feasible specimen preparation techniques result in some modification of the airborne particulate matter. Even the collection of particles from a three-dimensional airborne dispersion on to a two-dimensional filter surface can be considered a modification of the particulate matter, and some of the particles, in most samples, are modified by the specimen preparation procedures. However, the procedures specified in this test method are designed to minimize the disturbance of the collected particulate material. 5.2 This test method applies to analysis of a single filter and describes the precision attributable to measurements for a single filter (see 13.1 ). Multiple air samples are usually necessary to characterize airborne asbestos concentrations across time and space. The number of samples necessary for this purpose is proportional to the variation in measurement across samples, which may be greater than the variation in a measurement for a single sample.