The Effect on Fit of Multiple Consecutive Donning and Doffing of N95 Filtering Facepiece Respirators

Abstract

Background N95 filtering facepiece respirators (FFRs) are widely used in healthcare to reduce transmission of airborne infectious diseases. These respirators are generally described as single use or limited reuse devices, but cost and operational issues mean that they may be donned and doffed multiple times. There is scant research on the effect of this practice on adequacy of fit. Objective The purpose of this study was to measure the effect on respirator fit of multiple donning and doffing of N95 FFRs. Methods This was an experiment in which 16 women and 9 men employed by the National Institute for Occupational Health (NIOH), Johannesburg, donned their same N95 FFR six times. All 25 were trained in the correct wearing of the devices before the experiment. Four models of respirators were used: the six who did not use respirators at work (novice subjects) were issued a 3M 1860 FFR and the others used their currently supplied one. During the experiment subjects donned their respirators under the supervision of the tester. Quantitative fit testing was done in the NIOH Occupational Hygiene laboratory after each donning according to the OSHA-Accepted Fit Test Protocol using the TSI PortaCount Pro+ Model 8038 Respirator Fit Tester. During the test, fit was measured after each of seven exercises and then an overall fit factor was computed. Only individuals who achieved an initial overall fit factor of ≥100 were allowed to continue participation in the study. Median overall fit factors were calculated for the 25 subjects for each donning and changes across them was examined using Wilcoxon rank sum tests. Men and women and frequent and infrequent users were compared across the six tests. Infrequent use was defined as subjects who wore respirators ≤ once per week, and novice subjects. Results Two subjects (8%) had an overall fit factor <100 at fit Test 2, 6 (24%) at Test 3, and 8 (32%) at Tests 4, 5, and 6. Thirteen respirator users (52%) achieved ≥100 throughout the fit testing, so 12 had at least one failure at either Tests 2–6. Five of the 12 subjects with at least one failure showed persistent failures on all subsequent donnings. Six subjects out of 12 (50%) who failed a fit test achieved an overall fit factor >100 at a subsequent test. There was a significant difference between the median first and sixth overall fit factors (195 versus 150; P = 0.0271), but not between the second and sixth (161 versus 150; P = 0.3584). Men and women had similar overall fit factors, but infrequent users had larger average overall fit factors than frequent users after all six donnings. Conclusion Forty-eight percent of study subjects failed at least one fit test after re-donning an N95 FFR. The fit test data suggest that donning practices probably accounted for the fit test failures. The 50% of subjects who produced overall fit factors ≥100 after a test of <100 supports this contention.

Managing ICU surge during the COVID-19 crisis: rapid guidelines

“…In addition, fit and filtration are reported to degrade with extended use [98]. Frequent donning and doffing of the same contaminated mask increases HCW contamination risk [99] and compromise fit [100].…”

Scalable, effective, and rapid decontamination of SARS-CoV-2 contaminated N95 respirators using germicidal ultra-violet C (UVC) irradiation device

“…This is indicative of the fact that FFRs are only able to withstand a certain amount of decontamination cycles before the performance is compromised. Furthermore, studies have suggested that repetitive donning and removal FFRs result in impaired mask fit 29 , indicating that such respirators can only be reused a very small amount of time regardless of the decontamination efficiency. While there are no strict guides explaining the possible number of reuses for FFRs, the CDC recommends no more than 5 reuses based on two studies [29][30][31] .…”

“…Furthermore, studies have suggested that repetitive donning and removal FFRs result in impaired mask fit 29 , indicating that such respirators can only be reused a very small amount of time regardless of the decontamination efficiency. While there are no strict guides explaining the possible number of reuses for FFRs, the CDC recommends no more than 5 reuses based on two studies [29][30][31] . Therefore, a non-deleterious germicidal protocol can be implemented for the decontamination of FFRs to support the safe reuse for a limited number of times.…”

The impact of extreme reuse and extended wear conditions on protection provided by a surgical-style N95 filtering facepiece respirator

“…It was noted that (including the data for the two replacements FFRs) after 18-19 wearer use sessions on Day 5, the GRPF for all subjects was less than the initial GRPF measured at the time that the FFRs were quantitatively fitted to the subjects (Student's t-test single tail alpha 0.05). However, it remains unclear how much of this degradation is due to reduction in quality of fit, and how much is due to a reduction in the care that was taken to fit the respirator as time progressed (as was concluded by Vuma et al (2019)); this latter factor is difficult to control for in a human study. It is likely that some degradation of quality of fit, as a result of reduced care in donning taken by the wearer, would occur in reality, and that without some form of quantitative check of donning quality on a regular basis, this effect could reduce the protection provided to a wearer over a long period of time by any FFR style, whether new or used.…”

“…The reuse of different N95 FFR devices donned and doffed up to 20 times with only 2 min between reuses showed that the protection performance tended to decrease overall but five total wears could be achieved with the FF not dropping below 100 (Bergman et al 2012). In a follow-on study (Vuma et al 2019) evaluating the effect of multiple donnings on respirator fit in health laboratory service employees examining six wears, training of the wearer to maintain repeated correct donning was more important than any loss of ability of the FFR to fit. A report by the Emergency Care Research Institute [ECRI] 2020) on the safety of extended use and reuse of N95 respirators provides practical guidance on the potential risks and benefits that clinical centers should consider during decision making about N95 respirator reuse or extended use.…”