Testing of a mobile heating facility to sanitize N-95 respirators against an enveloped respiratory virus

In the spring of 2020, the Alaska Native Tribal Health Consortium (ANTHC) designed and built a sanitizing treatment system to address shortages of filtering facepiece respirators (FFRs). The design criteria included sanitizing large numbers of FFRs, repeatedly achieving FFR fit test requirements, and deactivating enveloped respiratory viruses, such as SARS-CoV-2. The outcome was the Mobile Sanitizing Trailer (MST), a 20 by 8-foot modified trailer designed to process up to 1,000 FFRs during a standard heat cycle. This paper reports on the MST's ability to: (1) sustain a target temperature, (2) produce tolerable conditions for FFRs as measured by fit factor and (3) successfully deactivate an infectious model virus. We found that the MST reliably and uniformly produced 75 degrees Celsius in the treatment chamber for the prescribed periods. Quantitative analysis showed that the FFRs achieved acceptable post-treatment fit factor even after 18, 60-minute heat cycles. Finally, the treated FFR materials had at least a log 3.0 reduction in viral RNA and no viable virus after 30, 60 or 90 minutes of heat treatment. As a sanitizing treatment during supply shortages, we found the MST a viable option for deactivation of virus and extending the usable life of FFRs.