Failure Rates During Reuse of Disposable N95 Masks in Clinical Practice in the Emergency Department

INTRODUCTION: The coronavirus 2019 pandemic caused a shortage of disposable N95 respirators, prompting healthcare entities to extend the use of these masks beyond their intended single-use manufacturer recommendation with a paucity of supporting research. METHODS: We performed a prospective cohort study of ED healthcare workers (HCW) (“subjects”) required to use respirators at an academic, Level I trauma center. Subjects had been previously fit tested and assigned an appropriately sized N95 mask per hospital protocol. Per study protocol, subjects were fit tested periodically throughout their shifts and on multiple shifts over the eight-week study period. Data points collected included the age of the mask, subjective assessment of mask seal quality, and fit test results. We analyzed the data using Fisher’s exact test, and calculated odds ratios (OR) to determine the failure rate of disposable N95 masks following reuse. RESULTS: A total of 130 HCWs underwent fit testing and 127 were included for analysis. Mask failure rate climbed after day 2 of use, with 33.3% of masks failing at day 3, 42.9% at day 4, and 50% at ≥ day 5. Categorizing the masks into those being used for two or fewer days vs those in use for three or more, failure was more common on day 3 of use or older compared to those in the first two days of use (41.8% vs 8.3%, P < 0.0001) with an OR of failure with an older mask of 7.9 (confidence interval [CI], 2.8–22.3). The healthcare workers’ assessment of poor seal was 33.3% sensitive (CI, 18.6–51.9) and 95.7% specific (CI, 88.8–98.6) for fit test failure. CONCLUSION: Disposable N95 masks have significant failure rates following reuse in clinical practice. Healthcare personnel also performed poorly in assessing the integrity of the seal of their disposable respirators.