Use, re-use or discard? Quantitatively defined variance in the functional integrity of N95 respirators following vaporized hydrogen peroxide decontamination during the COVID-19 pandemic

Abstract

Background: Coronavirus disease 2019 has stretched the ability of many institutions to supply needed personal protective equipment, especially N95 respirators. N95 decontamination and re-use programmes provide one potential solution to this problem. Unfortunately, a comprehensive evaluation of the effects of decontamination on the fit of various N95 models using a quantitative fit test (QNFT) approach is lacking.

Aims: To investigate the effects of up to eight rounds of vaporized hydrogen peroxide (VHP) decontamination on the fit of N95 respirators currently in use in a hospital setting, and to examine if N95 respirators worn by one user can adapt to the face shape of a second user with no compromise to fit following VHP decontamination.

Methods: The PortaCount Pro+ Respirator Fit Tester Model 8038 was used to quantitatively define functional integrity, measured by fit, of N95 respirators following decontamination with VHP.

Findings: There was an observable downward trend in the functional integrity of Halyard Fluidshield 46727 N95 respirators throughout eight cycles of decontamination with VHP. Functional integrity of 3M 1870 N95 respirators was reduced significantly after the respirator was worn, decontaminated with VHP, and then quantitatively fit tested on a second user. Furthermore, inconsistencies between qualitative fit test and QNFT results were uncovered that may have strong implications on the fit testing method used by institutions.

Conclusions: The data revealed variability in the functional integrity of different N95 models after VHP decontamination, and exposed potential limitations of N95 decontamination and re-use programmes.

Keywords: COVID-19; Decontamination; N95; Quantitative fit test; Respirator.

Figure 1

Fit test frequency and distribution of N95 respirators by University Hospital, Newark, NJ, USA. (A) The frequency of qualitative fit tests increased 10-fold and (B) the diversity of N95 models expanded since the beginning of the coronavirus disease 2019 pandemic.

Figure 2

Quantitative fit testing of N95 respirators commonly used at University Hospital, Newark, NJ, USA between January and May 2020. These data defined quantitatively difficult-to-fit N95 models: Cardinal Health, Gerson 1730 and Gerson 2130. Bars represent the median. 3M 1860/3M 1806S N=7, 3M 1870 N=4, 3M 9210 N=4, Halyard Fluidshield 46727 N=5, Cardinal Health N=10, Gerson 1730 N=10, Gerson 2130 N=9.

Figure 3

Decontamination with vaporized hydrogen peroxide does not affect the integrity of (A) 3M 1860, (B) 3M 1870 or (C) 3M 9210 N95 respirators, but potentially reduces the functional integrity of (D) Halyard Fluidshield 46727 N95 respirators. No significant differences were observed between decontamination cycles for any model. However, there was an observable downward trend in the functional integrity of Halyard Fluidshield 46727 N95 respirators throughout eight cycles of decontamination. Bars represent the median.

Figure 4

Comparison of the functional integrity of N95 respirators that had not been worn previously with N95 respirators that had been lightly worn. (A) 3M 1870 N95 respirators that were lightly worn, decontaminated for six cycles, and fit on a new second user (open circles) had a significant decrease in functional integrity compared with 3M 1870 N95 respirators that were decontaminated for six cycles but had not been worn previously (closed circles). No significant trends were found in the functional integrity of (B) 3M 1860/3M 1860S, (C) 3M 9210 or (D) Halyard Fluidshield 46727 N95 respirators when they had been worn previously.