Hydrogen Peroxide Vapor Decontamination of N95 Respirators for Reuse.

OBJECTIVE: The COVID-19 pandemic has led to global shortages of N95 respirators. Reprocessing of used N95 respirators may provide a higher filtration crisis alternative, but it is unknown if effective sterilization can be achieved for a virus without impairing respirator function. We evaluated the viricidal efficacy of Bioquell vaporized hydrogen peroxide (VHP) on contaminated N95 respirators and tested the particulate particle penetration and inhalation/exhalation resistance of respirators after multiple cycles of VHP. METHODS: 3M 1870 N95 respirators (3M, St. Paul, MN) were contaminated with 3 aerosolized bacteriophages: T1, T7, and Pseudomonas phage phi-6 followed by one cycle of VHP decontamination using a BQ-50 system (Bioquell, Horsham, PA). Additionally, new and unused respirators were sent to an independent laboratory, Nelson Labs (Salt Lake City, UT), for particulate filter penetration testing and inhalation/exhalation resistance after 3 and 5 cycles of VHP. RESULTS: A single VHP cycle resulted in complete eradication of bacteriophage from respirators (limit of detection 10 PFU). Respirators showed acceptable limits for inhalation/exhalation resistance after 3 and 5 cycles of VHP. Respirators demonstrated a filtration efficiency >99 % after 3 cycles, but fell below 95% after 5 cycles of HPV. CONCLUSION: Bioquell VHP demonstrated high viricidal activity for N95 respirators inoculated with aerosolized bacteriophages. Bioquell technology can be scaled for simultaneous decontamination of a large number of used but otherwise intact respirators. Reprocessing should be limited to 3 cycles due to concerns both about impact of clinical wear and tear on fit, and to decrement in filtration after 3 cycles.