After the WHO designated COVID-19 a global pandemic, face masks have become a precious commodity worldwide. However, uncertainty remains around several details regarding face masks, including the potential for transmission of bioaerosols depending on the type of mask and secondary spread by face masks. Thus, understanding the interplay between face mask structure and harmful bioaerosols is essential for protecting public health. Here, we evaluated the microbial survival rate at each layer of commercial of filtering facepiece respirators (FFRs) and surgical masks (SMs) using bacterial bioaerosols. The penetration efficiency of bacterial particles for FFRs was lower than that for SMs; however, the microbial survival rate for all tested masks was >13%, regardless of filtration performance. Most bacterial particles survived in the filter layer (44%–77%) (e.g., the core filtering layer); the outer layer also exhibited significant survival rates (18%–29%). Most notably, survival rates were determined for the inner layers (<1% for FFRs, 3%–16% for SMs), which are in contact with the respiratory tract. Our comparisons of the permeability and survival rate of bioaerosols in each layer will contribute to bioaerosol-face mask research, while also providing information to facilitate the establishment of a mask-reuse protocol.

中文翻译：

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商用口罩过滤层空气微生物存活率评价

在世卫组织将 COVID-19 指定为全球大流行之后，口罩已成为世界范围内的珍贵商品。然而，关于口罩的几个细节仍然存在不确定性，包括生物气溶胶传播的可能性取决于口罩的类型和口罩的二次传播。因此，了解口罩结构与有害生物气溶胶之间的相互作用对于保护公众健康至关重要。在这里，我们使用细菌生物气溶胶评估了过滤式面罩呼吸器 (FFR) 和外科口罩 (SM) 每一层商品的微生物存活率。细菌颗粒对 FFRs 的渗透效率低于 SMs；然而，无论过滤性能如何，所有经过测试的口罩的微生物存活率都大于 13%。大多数细菌颗粒在过滤层（44%–77%）（例如，核心过滤层）中存活；外层也表现出显着的存活率（18%–29%）。最值得注意的是，确定了与呼吸道接触的内层（FFR < 1%，SM 为 3%–16%）的存活率。我们对每一层生物气溶胶的渗透性和存活率的比较将有助于生物气溶胶面罩的研究，同时也提供信息以促进面罩重复使用协议的建立。