1.1 本规程介绍了确定检测限（DL）的程序 2. 用于测量纤维或结构 3. 使用显微镜方法。 1.2 本规程适用于通过相差显微镜（PCM）或透射电子显微镜（TEM）分析的空气样品，以及通过TEM分析的灰尘样品。 1.3 显微镜法需要计算石棉结构，并将结果报告为每立方厘米空气的结构（str/cc）或每立方厘米空气的纤维（f/cc），用于空气样品和每平方厘米表面积的结构（str/cm） 2. )对于灰尘样本。 1.4 以国际单位制表示的数值应视为标准值。本标准不包括其他计量单位。 1.5 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户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。 1.6 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）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》中确立的国际公认标准化原则制定的。 ====意义和用途====== 4.1 DL概念解决了潜在的测量解释错误。当测量的石棉水平无法与背景污染水平明确区分时，它用于控制报告石棉阳性发现的可能性。具体来说，如果测量水平与背景水平在统计上没有差异，则将测量报告为“低于DL”。 4.2 在为特定应用选择测量方法时，使用DL以及其他测量特性，如偏差和精度。 DL应在方法开发阶段或方法的特定应用之前建立。方法开发人员随后会将该方法宣传为具有特定DL。如果有其他测量方法可用，计划收集和分析样本的分析员会希望选择一种具有适合预期应用的DL的测量方法。 5. 因此，DL最重要的使用发生在研究的规划阶段，即收集和分析样本之前。

1.1 This practice presents the procedure for determining the detection limit (DL) 2 for measurements of fibers or structures 3 using microscopy methods. 1.2 This practice applies to samples of air that are analyzed either by phase contrast microscopy (PCM) or transmission electron microscopy (TEM), and samples of dust that are analyzed by TEM. 1.3 The microscopy methods entail counting asbestos structures and reporting the results as structures per cubic centimeter of air (str/cc) or fibers per cubic centimeter of air (f/cc) for air samples and structures per square centimeter of surface area (str/cm 2 ) for dust samples. 1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.5 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. 1.6 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 ====== 4.1 The DL concept addresses potential measurement interpretation errors. It is used to control the likelihood of reporting a positive finding of asbestos when the measured asbestos level cannot clearly be differentiated from the background contamination level. Specifically, a measurement is reported as being “below the DL” if the measured level is not statistically different than the background level. 4.2 The DL, along with other measurement characteristics such as bias and precision, is used when selecting a measurement method for a particular application. The DL should be established either at the method development stage or prior to a specific application of the method. The method developer subsequently would advertise the method as having a certain DL. An analyst planning to collect and analyze samples would, if alternative measurement methods were available, want to select a measurement method with a DL that was appropriate for the intended application. 5 The most important use of the DL, therefore, takes place at the planning stage of a study, before samples are collected and analyzed.