Talking and Deep Breathing Are Head Movements Associated with Leakage of Cup-Shaped and Foldable N95 Masks

DOI: 10.5176/2251-3833_GHC16.14

Authors: Chen-Peng Chen and Yi-Chun Lin

Abstract: N95 masks are frequently used in hospital and healthcare facility for protection of medical and nursing staff from exposure to airborne particulate contaminants and biological agents. However, the inward leakage may occur when the facial fit of the mask decreases as a result of improper size selection or use. This study investigated the fit of N95 masks commonly used in Taiwan by medical and nursing staff as influenced by head movement when the user performed on the job. A total of 120 participants (60 males and 60 females) were qualitatively fittested with three N95 masks of representative facepiece design using the test protocol required by the US Occupational Safety and Health Administration as an element in the respiratory protection program. The facepiece designs of the studied masks included the conventional cup-shaped design (cup design), the three-flap foldable design (folded design), and the cup design with an elastomeric liner inside the mask and with an exhalation valve (linered design). The participants were required to complete a sequence of seven exercises during the test, including, in the order of increasing stress to the mask, normal breathing, deep breathing, turning head side-to-side, moving head up-and-down, talking, and bending over. As the results show, only 27{6e6090cdd558c53a8bc18225ef4499fead9160abd3419ad4f137e902b483c465} of the participants passed all seven exercises without a leakage detected, with the proportion in males being significantly higher than that of females. The percentage of the participants failing all exercises was the greatest with the linered design and the least with the folded design. Talking and deep breathing resulted in higher rate of leakage than the other activities when the masks of cup and folded designs were tested. These results suggested a need to individually fit-test the N95 mask user to confirm the facial fit before the mask is used. The user should also consider the activities the mask is to be used with when selecting a respirator so to reduce potential exposure as a result of improper fit.

Keywords: N95 masks; respirator fit; inward leakage