RAPID: Evaluating Reprocessed N95 Facemask Filtration Efficiency Changes Across the Particle Size Distribution Spectrum

COVID-19健康危机导致许多临床工作者所需的防护口罩（如N95呼吸器）严重短缺。N95呼吸器（通常被称为N95口罩）由无纺布聚丙烯纤维层组成，这些纤维层结合在一起，形成足够的空隙，可以保留颗粒，但允许相对自由的气流。虽然N95呼吸器是为一次性使用而设计的，但它们的供应短缺已经变得严重，特别是对临床工作人员来说，可能会危及生命。由于这种短缺导致一些机构考虑消毒和重复使用N95口罩，因此确定N95材料在消毒后是否保留其基本防护特性（过滤效率、弹性等）至关重要。在这个由数学和物理科学理事会资助的项目中，Richard Peltier教授和他的学生正在评估N95材料在不同灭菌过程前后的气流和颗粒保留特性。灭菌过程包括紫外线、汽化过氧化氢和微波辐射。这项研究产生的数据正在向公众实时提供。本项目旨在确定经过不同再消毒方案的N95口罩的基本结构变化所造成的影响。具体的重点是亚微米范围的颗粒尺寸（6 - 900纳米）。核心问题是，再灭菌是否不仅改变了可以通过材料的颗粒总数，而且改变了逃逸颗粒大小的分布。为了解决这个问题，Peltier教授采用了单粒子计数/电迁移技术。对社会的更广泛影响是关于N95口罩可重复使用性的重要信息，N95口罩是为单次使用而设计的，但由于COVID-19大流行，目前供不应求。虽然该项目的结果最终将在传统文献中发表，但一旦产生结果草案，将立即在一个公共网站上发布。这笔拨款是使用《冠状病毒援助、救济和经济安全（关怀）法案》分配给MPS的补充资金提供的资金。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The COVID-19 health crisis has resulted in a critical shortage of protective facemasks, such as N95 respirators, required by many clinical workers. N95 respirators (often called N95 masks) are constructed of non-woven polypropylene fiber layers that are bound together to create sufficient voids that retain particles, but allow for relatively free airflow. While N95 respirators were designed for single use, their short supply has become acute and potentially life threatening especially for workers in clinical settings. As this shortage leads some institutions to consider sterilization and re-use of N95 respirators, it is critically important to determine whether N95 materials retain their fundamental protective features (filtration efficiency, resiliency, etc) after sterilization. In this project, funded by the Directorate of Mathematical and Physical Sciences, Professor Richard Peltier and his students are evaluating the airflow and particulate retention properties of N95 materials before and after different sterilization processes. The sterilization processes include ultraviolet light, vaporized hydrogen peroxide, and microwave radiation. The data produced by the study are being made available to the public in real time.This project seeks to identify effects caused by fundamental structural changes in N95 respirators that are subjected to different re-sterilization protocols. The specific focus is on the sub-micron range of particle size (6 – 900 nanometers). The central question is whether re-sterilization changes not only the total number of particles that can pass through the material, but if the distribution of escaping particle sizes changes. To address this question, Professor Peltier employs single particle counting/electric mobility technology. The broader impact to society is important information on the re-usability of N95 respirators that are designed for single use, but are now in short supply because of the COVID-19 pandemic. While the results of this project will ultimately be published in the traditional literature, draft results are being released to a public website as soon as they are produced.This grant is being awarded using funds made available by the Coronavirus Aid, Relief, and Economic Security (CARES) Act supplemental funds allocated to MPS.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.