Expiratory aerosol particle escape from surgical masks due to imperfect sealing.
Expiratory aerosol particle escape from surgical masks due to imperfect sealing.
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DOI：
10.1038/s41598-021-91487-7
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发表时间：
2021-06-08
影响因子：
4.6
通讯作者：
Ristenpart WD
中科院分区：
文献类型：
--
作者：
Cappa CD;Asadi S;Barreda S;Wexler AS;Bouvier NM;Ristenpart WD
佩戴医用口罩或其他类似的面罩可以减少因呼吸、说话、咳嗽或打喷嚏而产生的呼气颗粒物的排放。虽然已经确定，部分呼气气流在口罩边缘周围泄漏，但这些泄漏气流如何影响口罩阻止呼气气溶胶颗粒排放的整体效率尚不清楚。在这里，我们的实验表明，与不戴口罩相比，外科口罩周围泄漏气流中的气溶胶颗粒浓度降低了，减少的幅度取决于逃生方向(从顶部、侧面或底部)。由于每个方向的实际泄漏流量很难测量，因此我们使用蒙特卡罗方法来估计所有方向上直径在0.5-20μM范围内的颗粒的流动校正颗粒发射率。在此基础上，我们推导出了基于流量加权的基于粒子总数的遮罩去除效率。与通过口罩的过滤效率相比，口罩的整体效率(包括通过口罩的空气和泄漏流量)降低，说话的效率从93%下降到70%，但咳嗽的效率只有94%-90%。这些结果表明，由于密封不完善导致的泄漏流动确实会降低口罩减少呼气颗粒物排放的效率，但即使有这种泄漏，医用口罩仍能提供实质性的控制。
Wearing surgical masks or other similar face coverings can reduce the emission of expiratory particles produced via breathing, talking, coughing, or sneezing. Although it is well established that some fraction of the expiratory airflow leaks around the edges of the mask, it is unclear how these leakage airflows affect the overall efficiency with which masks block emission of expiratory aerosol particles. Here, we show experimentally that the aerosol particle concentrations in the leakage airflows around a surgical mask are reduced compared to no mask wearing, with the magnitude of reduction dependent on the direction of escape (out the top, the sides, or the bottom). Because the actual leakage flowrate in each direction is difficult to measure, we use a Monte Carlo approach to estimate flow-corrected particle emission rates for particles having diameters in the range 0.5–20 μm. in all orientations. From these, we derive a flow-weighted overall number-based particle removal efficiency for the mask. The overall mask efficiency, accounting both for air that passes through the mask and for leakage flows, is reduced compared to the through-mask filtration efficiency, from 93 to 70% for talking, but from only 94–90% for coughing. These results demonstrate that leakage flows due to imperfect sealing do decrease mask efficiencies for reducing emission of expiratory particles, but even with such leakage surgical masks provide substantial control.
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影响因子：
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