Standard hospital blanket warming cabinets can be utilized for complete moist heat SARS-CoV2 inactivation of contaminated N95 masks for re-use.

Shortages of personal protective equipment for use during the SARS-CoV-2 pandemic continue to be an issue among health-care workers globally. Extended and repeated use of N95 filtering facepiece respirators without adequate decontamination is of particular concern. Although several methods to decontaminate and re-use these masks have been proposed, logistic or practical issues limit adoption of these techniques. In this study, we propose and validate the use of the application of moist heat (70 °C with humidity augmented by an open pan of water) applied by commonly available hospital (blanket) warming cabinets to decontaminate N95 masks. This report shows that a variety of N95 masks can be repeatedly decontaminated of SARS-CoV-2 over 6 h moist heat exposure without compromise of their filtering function as assessed by standard fit and sodium chloride aerosol filtration efficiency testing. This approached can easily adapted to provide point-of-care N95 mask decontamination allowing for increased practical utility of mask recycling in the health care setting.

Decontamination of N95 masks for re-use employing 7 widely available sterilization methods.

The response to the COVID-19 epidemic is generating severe shortages of personal protective equipment around the world. In particular, the supply of N95 respirator masks has become severely depleted, with supplies having to be rationed and health care workers having to use masks for prolonged periods in many countries. We sought to test the ability of 7 different decontamination methods: autoclave treatment, ethylene oxide gassing (ETO), low temperature hydrogen peroxide gas plasma (LT-HPGP) treatment, vaporous hydrogen peroxide (VHP) exposure, peracetic acid dry fogging (PAF), ultraviolet C irradiation (UVCI) and moist heat (MH) treatment to decontaminate a variety of different N95 masks following experimental contamination with SARS-CoV-2 or vesicular stomatitis virus as a surrogate. In addition, we sought to determine whether masks would tolerate repeated cycles of decontamination while maintaining structural and functional integrity. All methods except for UVCI were effective in total elimination of viable virus from treated masks. We found that all respirator masks tolerated at least one cycle of all treatment modalities without structural or functional deterioration as assessed by fit testing; filtration efficiency testing results were mostly similar except that a single cycle of LT-HPGP was associated with failures in 3 of 6 masks assessed. VHP, PAF, UVCI, and MH were associated with preserved mask integrity to a minimum of 10 cycles by both fit and filtration testing. A similar result was shown with ethylene oxide gassing to the maximum 3 cycles tested. Pleated, layered non-woven fabric N95 masks retained integrity in fit testing for at least 10 cycles of autoclaving but the molded N95 masks failed after 1 cycle; filtration testing however was intact to 5 cycles for all masks. The successful application of autoclaving for layered, pleated masks may be of particular use to institutions globally due to the virtually universal accessibility of autoclaves in health care settings. Given the ability to modify widely available heating cabinets on hospital wards in well-resourced settings, the application of moist heat may allow local processing of N95 masks.