ABSTRACT
At the beginning of the COVID-19 pandemic when traditional N95 respirators were in short supply in the United States, there was a need for alternative products that did not rely on traditional avenues of sourcing and manufacturing. The purpose of this research was to develop and test alternatives to N95 respirators that could be produced locally without specialized materials and processes. Through an interdisciplinary team of experts, new mask designs that use repurposed filtration media and commercially available components were developed and tested for filtration and fit against current N95 standards. Filtration efficiency test results showed that the filtration media can be used for high-quality facemasks and quantitative fit testing demonstrated that the new mask designs could be viable alternatives to traditional N95 facemasks when those masks are in short supply. Manufacturing viability was tested utilizing a workforce to create 6000 masks over 10 days. The ability to quickly produce masks at scale using a workforce without specialized skills demonstrated the feasibility of the mask designs and manufacturing approach to address shortages of critical healthcare equipment, mitigate risk for healthcare and essential workers, and minimize the transmission and spread of disease.
ABSTRACT
This study aims to evaluate the filtration performance of three commercially available (3M 8210 respirator, Halyard 48207 surgical mask, and 3M 1820 procedure mask) and two alternative face mask and respirator materials (Halyard H600 sterilization wrap and Cummins EX101) after selected decontamination treatments, including isopropanol (IPA) treatments (soaking or spraying), ultraviolet germicidal irradiation (UVGI), and heat treatments (dry heat at 77 °C or steam heat). Both IPA soaking and spraying removed most electrostatic charges on all four electret materials (three commercial and one alternative), causing significant deterioration of filtration efficiency to unacceptable level. The other non-electret alternative material sustained its N95-grade performance after both IPA soaking and spraying treatments, demonstrating the possible application of IPA disinfection for non-electret alternative respirator/mask materials. UVGI preserved the filtration of all three commercially available respirator/mask materials after up to 10 treatments, suggesting it can be a possible decontamination method for hospital and clinic use without compromising respirator/mask performance. The considerations of the practical implementation of this method was discussed. Between the two heat treatment methods tested, dry heat showed better compatibility with electret material by sustaining both filtration efficiency and fit (tested on commercial respirator only), although adding moisture was reported in favor of virus inactivation. Heat treatment is easily accessible method for general publics to implement at home, while it is recommended to maintain the moisture level below saturation. Comparing to size-integrated method, the size-resolved fractional efficiency measurement technique, although more time consuming, proved to be a better method for evaluating respirator/mask filtration performance after decontaminations by providing more sensitive detection of performance degradation and the capability of distinguishing charge loss to other mechanisms causing efficiency deterioration. Detailed descriptions are provided in methodology part to emphasize the cares needed for an appropriate efficiency evaluation. The limited results in this study on worn masks made of alternative sterilization wrap indicated possible performance degradation of electret material caused by normal human wearing activities, suggesting the need of assessing respirator/mask decontamination strategy by testing practically worn-and-decontaminated/reused samples instead of unworn only-decontaminated counterparts.