A Scalable Method of Applying Heat and Humidity for Decontamination of N95 Respirators During the COVID-19 Crisis

Loïc Anderegg; Cole Meisenhelder; Chiu Oan Ngooi; Lei Liao; Wang Xiao; Steven Chu; Yi Cui; John M Doyle

The fit tests were performed with a TSI PortaCount Respirator Fit Tester 8038 using NaCl particles produced by a particle generator. Each test was performed by a single user to control for variability in face structure. We used the OSHA modified ambient aerosol Condensation Nuclei Counter (CNC) Quantitative Fit Test for Filtering Facepiece Respirators. This produces a quantitative fit factor score for each of the four test components (bending over, talking, head side to side, head up and down) as well as an overall fit factor computed as the geometric mean of these four scores. A passing score is given in each category for a fit factor ≥100, but any individual category may be failed so long as the overall fit factor is ≥100 in order to pass the OSHA test. 1 The 1860 masks available were manufactured in 2006, with a shelf life of 5 years. Hence they were 9 years expired at the time of testing. As of 4/5/20 the CDC states that model 1860 masks beyond the manufacturer shelf life have been shown to still be in accordance with NIOSH performance standards [17] . Our testing is in agreement with these findings. CC-BY-NC 4.0 International license It is made available under a author/funder, who has granted medRxiv a license to display the preprint in perpetuity.