Vaporized hydrogen peroxide sterilization of powered air-purifying respirators: Efficacy and safety assessment

Abstract

The COVID-19 pandemic increased demand for personal protective equipment, necessitating exploration of reprocessing methods. This study evaluates the efficacy and safety of vaporized hydrogen peroxide (VHP) sterilization for potential reuse of three powered air purifying respirator (PAPR) brands (3 M, Kebiao, Honeywell). Geobacillus stearothermophilus spores (ATCC 7953) served as biological indicators, while performance parameters (filtration, airflow, battery) and material integrity were monitored throughout 60 cycles, with H₂O₂ residual concentrations measured after 30 cycles. VHP achieved 100 % sterilization efficacy under both unloaded (48/48 biological indicators) and fully-loaded (132/132 biological indicators) conditions, demonstrating complete microbial inactivation across all sampling sites. However, brand-specific sterilization varied across operational conditions. 3 M units achieved complete sterilization in respiratory conduits when powered off but showed reduced filter efficacy. Kebiao units demonstrated complete sterilization when powered off but reduced efficacy during operation at internal filtration sites. Honeywell units with activated carbon showed poor VHP compatibility, while non-activated carbon units performed better when powered off. After 60 cycles, all PAPRs maintained filtration efficiency > 99.97 % and airflow rates > 120 L/min, with functional battery performance. H₂O₂ residual concentrations significantly exceeded safety thresholds (<1 ppm): 3.2 (2.0,4.6) ppm for 3 M, 6.1 (4.3,7.4) ppm for Kebiao, and 6.5 (4.1,8.2) ppm for Honeywell units, with 3 M showing significantly lower residuals (P < 0.05). This study provides critical evidence supporting VHP as a promising approach for PAPR sterilization. However, brand-specific protocols and extended ventilation procedures are required to ensure effective sterilization and reduce H₂O₂ residues to safe level.