Document Type



The battle with COVID-19 pandemic has resulted in the shortage of personal protective equipment, particularly, N95 respirators. Healthcare workers who reused N95 respirators may resort to unproven methods of cleaning/sterilization that can severely compromise the respirators’ filtration efficiency. A recently issued guideline will test decontaminated N95 respirators against particles with a median diameter of 0.075 ± 0.020 µm at a flow rate of 85 L min–1. For emergency reuse, these conditions may be too stringent. N95 respirators tested at this flow rate had predicted efficiencies of < 69%, assuming complete degradation of their electrostatic coating. Experimental efficiencies were ~15% lower. For emergency reuse, we recommend to either adjust the flow rate closer to normal breathing, or the size of the test particle should reflect that of virus-laden respiratory aerosols (~> 0.5 µm). By reconsidering the test conditions, a substantial fraction of used/decontaminated respirators can be reused.

Digital Object Identifier (DOI)

APA Citation

Vejerano, E. P., & Ahn, J. (2020). A letter to reconsider the conditions for testing decontaminated N95 respirators for emergency reuse to address shortage. Aerosol and Air Quality Research, 20(8), 1713–1715.


© The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited.