A comparative empirical analysis of low-cost decontamination methods for filtering facepiece respirators to address stock shortages during the COVID-19 Pandemic

ABSTRACT

Introduction: Filtering facepiece respirators (FFRs) reuse practices to address shortages during the COVID-19 pandemic received attention;however, evidence of SARS-CoV-2 inactivation on respirators is limited. Quality FFRs for use during outbreaks remains a priority to protect frontline and essential workers. This study aimed to compare the effectiveness of three relatively inexpensive methods to inactivate SARS-CoV-2 and ensuring respirator performance. Methods: Seven FFRs inoculated with SARS-CoV-2 were decontaminated with moist heat incubation (MHI), vapourised hydrogen peroxide (VHP), and ultraviolet germicidal irradiation (UVGI). G.stearothermophilus bioindicator was used as a control. FFR integrity, efficiency and user fit were assessed on 27 participants for 30 decontamination cycles. Ethical clearance was acquired from the University of the Witwatersrand (M200684). Results: Most participants failed fit testing for KN95 irrespective of method used except for two individuals. Participants completed more cycles after UVGI compared to VHP decontamination. Only KN95 failed filtration post-MHI, VHP and UVGI treatment. A ≥ 3 log reduction of SARS-CoV-2 was achieved using UVGI for worn FFRs (Greenline 5200 FFP2 and Makrite 9500 N95 using MHI;3M 8810SSA FFP2 using VHP;Greenline 5200 FFP2). UVGI and VHP methods achieved a 6 log reduction of G.stearothermophilus. Conclusion: Some FFRs could withstand 30 cycles of UVGI and VHP processing without diminishing filtration efficiency or fit. SARS-CoV-2 log reduction varied across the methods and FFRs models emphasing the importance of validation before reuse during a crisis.