4C Air, Inc., Sunnyvale, California 94089, United States.
Department of Physics, Stanford University, Stanford, California 94305, United States.
ACS Nano. 2020 May 26;14(5):6348-6356. doi: 10.1021/acsnano.0c03597. Epub 2020 May 5.
The coronavirus disease 2019 (COVID-19) pandemic has led to a major shortage of N95 respirators, which are essential for protecting healthcare professionals and the general public who may come into contact with the virus. Thus, it is essential to determine how we can reuse respirators and other personal protective equipment in these urgent times. We investigated multiple commonly used disinfection schemes on media with particle filtration efficiency of 95%. Heating was recently found to inactivate the virus in solution within 5 min at 70 °C and is among the most scalable, user-friendly methods for viral disinfection. We found that heat (≤85 °C) under various humidities (≤100% relative humidity, RH) was the most promising, nondestructive method for the preservation of filtration properties in meltblown fabrics as well as N95-grade respirators. At 85 °C, 30% RH, we were able to perform 50 cycles of heat treatment without significant changes in the filtration efficiency. At low humidity or dry conditions, temperatures up to 100 °C were not found to alter the filtration efficiency significantly within 20 cycles of treatment. Ultraviolet (UV) irradiation was a secondary choice, which was able to withstand 10 cycles of treatment and showed small degradation by 20 cycles. However, UV can potentially impact the material strength and subsequent sealing of respirators. Finally, treatments involving liquids and vapors require caution, as steam, alcohol, and household bleach all may lead to degradation of the filtration efficiency, leaving the user vulnerable to the viral aerosols.
新型冠状病毒肺炎（COVID-19）大流行导致 N95 呼吸器严重短缺，而 N95 呼吸器对于保护可能接触病毒的医护人员和公众至关重要。因此，在这个紧急时期，确定如何重复使用呼吸器和其他个人防护设备至关重要。我们研究了多种常用的消毒方案，涉及过滤效率为 95%的介质。最近发现，加热可在 70°C 下 5 分钟内使溶液中的病毒失活，并且是最具可扩展性、用户友好的病毒消毒方法之一。我们发现，在各种湿度（≤100%相对湿度，RH）下加热（≤85°C）是保持熔喷织物和 N95 级呼吸器过滤性能的最有前途的、非破坏性方法。在 85°C、30%RH 的条件下，我们能够进行 50 次热处理循环，而过滤效率没有明显变化。在低湿度或干燥条件下，在 20 次处理循环内，温度高达 100°C 不会显著改变过滤效率。紫外线（UV）辐照是一种次要选择，能够承受 10 次处理循环，并且在 20 次处理循环后仅略有降解。然而，UV 可能会影响材料强度和呼吸器的后续密封。最后，涉及液体和蒸气的处理需要谨慎，因为蒸汽、酒精和家用漂白剂都可能导致过滤效率降低，使使用者容易受到病毒气溶胶的侵害。
