Can N95 respirators be reused after disinfection? And for how many times?

Lei Liao; Wang Xiao; Mervin Zhao; Xuanze Yu; Haotian Wang; Qiqi Wang; Steven Chu; Yi Cui

is the (which was not peer-reviewed) The copyright holder for this preprint . https://doi.org/10.1101/2020.04.01.20050443 doi: medRxiv preprint important to develop procedures for the safe and frequent re-use of FFRs without reducing the filtration efficiency. The CDC has recommended many disinfection or sterilization methods, typically involving chemical, radiative, or temperature treatments. 27 In brief, we can summarize the mechanism of disinfection or sterilization of bacteria and viruses as among the following: protein denaturation (alcohols, heat), DNA/RNA disruption (UV, peroxides, oxidizers), cellular disruption (phenolics, chlorides, aldehydes). While none of these methods have been extensively evaluated for SARS-CoV-2 inactivation specifically, we tested methods that can be easily deployed within a hospital setting with relatively high throughput for FFR reuse. Among the CDC forms of disinfection, we chose five commonly used and potentially scalable, user-friendly methods: 1) heat under various humidities (heat denaturation inactivates SARS-CoV with temperatures >65 °C in solution, potentially the SARS-CoV-2 with temperatures >70 °C), 28-30 2) steam (100 °C heat based denature), 3) 75% alcohol (denaturing of the virus, based on the CDC), 4) household diluted chlorine-based solution (oxidative or chemical damage, based on the CDC), and 5) ultraviolet germicidal irradiation (UVGI was able to inactivate the SARS-CoV in solution with UV-C light at a fluence of ~3.6 J/cm 2 ). 28 Using an oven, a UV-C sterilizer cabinet (found in barbershops or salons), steam, or liquid sprays can all realistically be deployed in the modern hospital setting and potentially in homes if needed. We did not consider some other common, but more inaccessible techniques (equipment such as author/funder, who has granted medRxiv a license to display the preprint in perpetuity.