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

Mathematical and Physical Sciences - 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.