Surgical mask covering of N95 filtering facepiece respirators: The risk of increased leakage

Abstract

In this report, we demonstrate the potential risk of increased face-to-mask seal leakage when N95 filtering facepiece respirators (N95 FFRs) are covered by surgical, cloth, or medical masks, (collectively referred to as surgical masks), through analytical modeling of the associated fluid mechanics and seal pressures. Previously published experimental studies of respirator pressures and leakage are applicable to this problem. Properly utilized N95 FFRs will remain an essential component of healthcare worker safety for the foreseeable future, especially for those engaged in aerosolgenerating procedures (AGPs) such as endotracheal intubation.1–3 When considering leakage risk, it is important to understand the general challenges to ensuring an adequatemask-to-face seal. The fit and seal degrade with repeated donning and doffing, and some N95 FFR reprocessing or recycling techniques have been reported to accelerate this degradation.4 In short, the N95 mask-to-face seal is fragile and can be compromised by a number of factors.