1.1 本试验方法用于测量医用口罩材料的细菌过滤效率（BFE），采用上游细菌挑战与下游残留浓度的比率来确定医用口罩材料的过滤效率。 1.2 本试验方法是一种定量方法，可测定医用口罩材料的过滤效率。该方法可确定的最大过滤效率为99.9 %. 1.3 本试验方法不适用于生物气溶胶暴露的所有形式或条件。试验方法的使用者应审查工人暴露的模式，并评估该方法对其特定应用的适用性。 1.4 本试验方法将医用口罩材料作为防护服项目进行评估，但不将其作为呼吸器进行监管批准。如果佩戴者需要呼吸保护，应使用NIOSH认证的呼吸器。 对特定医用口罩材料进行相对较高的细菌过滤效率测量并不能确保佩戴者免受生物气溶胶的影响，因为该测试方法主要评估用于制造医用口罩的复合材料的性能，而不是其设计、配合或面部密封性能。 1.5 单位- 以国际单位制或英寸-磅单位表示的数值应单独视为标准值。每个系统中规定的值可能不是精确的等效值；因此，每个系统应相互独立使用。将两个系统的值合并可能会导致不符合标准。 1.6 本试验方法不涉及医用口罩材料的透气性或影响通过医用口罩材料呼吸的任何其他特性。 1.7 该测试方法也可用于测量其他多孔医疗产品的细菌过滤效率（BFE），如手术服、手术巾和无菌屏障系统。 1.8 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。 1.9 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====== 5.1 本试验方法提供了一种评估医用口罩材料细菌过滤效率的程序。本试验方法未定义细菌过滤效率的可接受水平。因此，当使用本试验方法时，有必要描述进行试验的具体条件。 5.2 本试验方法专门用于测量医用口罩的细菌过滤效率，使用 金黄色葡萄球菌 作为挑战生物体。使用 金黄色葡萄球菌 基于其作为医院感染主要原因的临床相关性。 5.3 本试验方法旨在以28.3升/毫米的流速向试样引入细菌气溶胶激发。（1英尺 3. /最小值）。该流速在正常呼吸范围内，并且在级联冲击器的限制范围内。 5.4 除非另有规定，否则测试应在医用口罩内部与细菌挑战接触的情况下进行。可以通过试样的正面或内衬侧引导气溶胶激发进行测试，从而评估与患者产生的气溶胶和佩戴者产生的气溶胶相关的过滤效率。 5.5 物理、化学和热应力的降解可能会对医用面罩材料的性能产生负面影响。 在使用过程中，材料的完整性也可能受到弯曲和磨损等影响，或被酒精和汗水等污染物润湿。没有这些压力的测试可能会导致错误的安全感。如果这些条件值得关注，则在采用代表预期使用条件的适当预处理技术后，评估医用口罩材料的细菌过滤效率性能。考虑预处理，以评估一次性产品的储存条件和保质期的影响，以及可重复使用产品的清洗和灭菌效果。 5.6 如果此程序用于质量控制，请对较大的数据集进行适当的统计设计和分析。这类分析包括但不限于测试的单个样本数量、细菌过滤效率的平均百分比和标准差。以这种方式报告的数据有助于建立有关产品性能的置信限。 可接受的抽样计划示例见ANSI/ASQ Z1.4和ISO 2859-1等参考文献。

1.1 This test method is used to measure the bacterial filtration efficiency (BFE) of medical face mask materials, employing a ratio of the upstream bacterial challenge to downstream residual concentration to determine filtration efficiency of medical face mask materials. 1.2 This test method is a quantitative method that allows filtration efficiency for medical face mask materials to be determined. The maximum filtration efficiency that can be determined by this method is 99.9 %. 1.3 This test method does not apply to all forms or conditions of biological aerosol exposure. Users of the test method should review modes for worker exposure and assess the appropriateness of the method for their specific applications. 1.4 This test method evaluates medical face mask materials as an item of protective clothing but does not evaluate materials for regulatory approval as respirators. If respiratory protection for the wearer is needed, a NIOSH-certified respirator should be used. Relatively high bacterial filtration efficiency measurements for a particular medical face mask material does not ensure that the wearer will be protected from biological aerosols, since this test method primarily evaluates the performance of the composite materials used in the construction of the medical face mask and not its design, fit, or facial-sealing properties. 1.5 Units— The values stated in SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance of the standard. 1.6 This test method does not address breathability of the medical face mask materials or any other properties affecting the ease of breathing through the medical face mask material. 1.7 This test method may also be used to measure the bacterial filtration efficiency (BFE) of other porous medical products such as surgical gowns, surgical drapes, and sterile barrier systems. 1.8 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. 1.9 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 offers a procedure for evaluation of medical face mask materials for bacterial filtration efficiency. This test method does not define acceptable levels of bacterial filtration efficiency. Therefore, when using this test method it is necessary to describe the specific condition under which testing is conducted. 5.2 This test method has been specifically designed for measuring bacterial filtration efficiency of medical face masks, using Staphylococcus aureus as the challenge organism. The use of S. aureus is based on its clinical relevance as a leading cause of nosocomial infections. 5.3 This test method has been designed to introduce a bacterial aerosol challenge to the test specimens at a flow rate of 28.3 L/mm. (1 ft 3 /min). This flow rate is within the range of normal respiration and within the limitations of the cascade impactor. 5.4 Unless otherwise specified, the testing shall be performed with the inside of the medical face mask in contact with the bacterial challenge. Testing may be performed with the aerosol challenge directed through either the face side or liner side of the test specimen, thereby, allowing evaluation of filtration efficiencies which relate to both patient-generated aerosols and wearer-generated aerosols. 5.5 Degradation by physical, chemical, and thermal stresses could negatively impact the performance of the medical face mask material. The integrity of the material can also be compromised during use by such effects as flexing and abrasion, or by wetting with contaminants such as alcohol and perspiration. Testing without these stresses could lead to a false sense of security. If these conditions are of concern, evaluate the performance of the medical face mask material for bacterial filtration efficiency following an appropriate pretreatment technique representative of the expected conditions of use. Consider preconditioning to assess the impact of storage conditions and shelf life for disposable products, and the effects of laundering and sterilization for reusable products. 5.6 If this procedure is used for quality control, perform proper statistical design and analysis of larger data sets. This type of analysis includes, but is not limited to, the number of individual specimens tested, the average percent bacterial filtration efficiency, and standard deviation. Data reported in this way help to establish confidence limits concerning product performance. Examples of acceptable sampling plans are found in references such as ANSI/ASQ Z1.4 and ISO 2859-1.