N95 respirator: one size does not fit all

Abstract

It was a pleasure to read the article from Zuber A et al¹. in the recent online issue of JMS¹. The main prerequisites of a high-quality systematic review were met; however, some considerations about the available data about the importance of an appropriately sized mask, how to do fit testing, user check procedures before use, as there is limited knowledge about this among health care workers and is often neglected. We would like to elaborate on this information for further knowledge.

Healthcare workers (HCW) are at risk of transmission of droplet infections, especially when exposed to aerosol-generating procedures. The mainstay of preventing transmission in high-risk places is by using an appropriately fitted and worn respirator. For a respirator to be effective in preventing infection it should fulfill two criteria. It should prevent droplets to pass through the mask and ask should fit to create a seal on the face and minimize gaps. The presence of a leak around the mask depends on the compatibility of the respirator relative to facial anthropometry². Increased leakage was found in Asian females compared to Caucasians and Europeans, thus exposing such population to a higher risk of transmission of droplet infections³. Reported factors that influence proper fitting of respirator include age, sex, weight, race, facial length, nose length, and bridge width. Occupational Safety and Health Administration (OSHA) requires an annual fit test to confirm the fit and detect leaks of any respirator before it can be used by HCW⁴. Once a fit test has been done to determine the best respirator model and size for a particular user, a user seal check is mandatory every time the respirator is worn to ensure an adequate seal. There are two types of fit test⁵