Room Temperature Wait and Reuse for Bioburden Reduction of SARS-CoV-2 on N95 Filtering Facepiece Respirators

Introduction: During a pandemic, when the supply of N95 filtering facepiece respirators (FFRs) is limited, health care workers may reuse N95 FFRs. Room temperature storage of N95 FFRs—waiting before reuse—could be a simple low-cost method to reduce severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) bioburden in such a situation. The U.S. Centers for Disease Control and Prevention specify this as a strategy for reducing self-contamination risk during a time of N95 FFR shortage. Objective: To review the literature on persistence of SARS-CoV-2 on surfaces to assess room temperature waiting times for bioburden reduction on N95 FFRs. Methods: The literature was searched for studies evaluating room temperature persistence of SARS-CoV-2. A 3-log decay time was extracted from published data for quantitative comparison between different studies. Studies using surgical masks and non-peer-reviewed studies that include N95 FFRs were used to draw conclusions. Key Findings: Experimental and analytical choices vary between studies and impact the estimated 3-log decay time. There is not a clear understanding of which material properties are significant. There are no peer-reviewed studies of virus persistence on an N95 FFR. Discussion and Conclusions: SARS-COV-2 inactivation occurs spontaneously at room temperature. The precise timing depends on factors including humidity, temperature, and surface material. In reviewed studies, a 7-day waiting period encompasses the 3-log reduction in infectious titer of SARS-COV-2 on specific N95 FFRs and surgical masks. Owing to variations between studies and among N95 FFR materials and room temperature conditions, it is impossible to extrapolate from these limited data to assign a precise 3-log decay time for all used N95 FFRs.