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Quantitative Protection Factors for Common Masks and Face Coverings
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2021-02-18 , DOI: 10.1021/acs.est.0c07291
David Leith 1, 2 , Christian L'Orange 1 , John Volckens 1
Affiliation  

The performance of masks, whether intended to protect the community from exhaled infectious aerosol or to protect the wearer from inhaled infectious aerosol, depends on factors such as filtration efficiency, particle size distribution, leakage, and ventilation rate. These factors depend on the activities and facial features of the mask wearer so that the mask performance for real-world applications is difficult to predict. The present work shows how protection factor, a quantity often used to describe mask performance, can be estimated without involving human volunteers. By constraining these factors to known values, mask protection factors can be compared fairly and efficiently following a series of filtration efficiency measurements performed in the laboratory. Protection factors and mask emissions for exhalation and inhalation were evaluated for masks of seven types currently in use around the world and for a hypothetical mask with 99% efficiency on all particles. The performance of reusable masks made from cotton fabric was limited by the size of the native cotton fibers. Masks that utilized finer fibers, particularly electret fibers with relatively small diameters, showed excellent performance with moderate flow resistance. Results from this work, in addition to simple guidance for mask fit and usage, can facilitate risk communication and decision-making efforts during the COVID-19 pandemic.

中文翻译:

常见口罩和面罩的定量防护系数

口罩的性能,无论是为了保护社区免受呼出的传染性气溶胶的侵害,还是为了保护佩戴者免受吸入的传染性气溶胶的侵害,都取决于过滤效率、粒径分布、泄漏和通风率等因素。这些因素取决于面罩佩戴者的活动和面部特征,因此很难预测实际应用中的面罩性能。目前的工作展示了如何在不涉及人类志愿者的情况下估计防护系数(通常用于描述口罩性能的数量)。通过将这些因素限制在已知值,可以在实验室进行一系列过滤效率测量后公平有效地比较面罩防护因素。对目前世界各地使用的七种类型的口罩以及假设的对所有颗粒物的效率为 99% 的口罩的防护系数和面罩呼气和吸气排放进行了评估。由棉织物制成的可重复使用口罩的性能受到天然棉纤维尺寸的限制。使用更细纤维,特别是直径相对较小的驻极体纤维的口罩表现出优异的性能和适度的流动阻力。这项工作的结果,除了口罩佩戴和使用的简单指导之外,还可以促进 COVID-19 大流行期间的风险沟通和决策工作。
更新日期:2021-03-02
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