LAUSR

OBJECTIVE We quantitatively assessed the fit failure rate of N95 respirators according to the number of donning/doffing and hours worn. DESIGN Experimental study. SETTING A tertiary referral center. PARTICIPANTS Ten infection control practitioners participated in the fit test. METHODS The first experiment comprised four consecutive 1-hour donnings and fit tests between each donning. The second experiment comprised two consecutive 3-hour donnings and fit tests between each donning. The final experiment comprised fit tests after an 1-hour donning or a 2-hour donning. RESULTS For 1-hour donnings, 60%, 70%, and 90% of the participants had fit failures after two, three, and four consecutive donnings. For 3-hour donnings, 50% had fit failure after the first donning and 70% had failures after two consecutive donnings. All participants passed the fit test after re-fitting whenever fit failure occurred. The final experiment showed that 50% had fit failure after a single use of 1 hour, and 30% had fit failure after a single use of 2 hours. CONCLUSIONS High fit failure rates were recorded after repeated donning and extended use of N95 respirators. Caution is needed for reuse (≥ 1 time) and extended use (≥ 1 hour) of N95 respirators in high-risk settings such as those involving aerosol-generating procedures. Although adequate re-fitting may recover the fit factor, the use of clean gloves and strict hand hygiene afterward should be ensured when touching the outer surfaces of N95 respirators for re-fitting.