Effect of various decontamination procedures on disposable N95 mask integrity and SARS-CoV-2 infectivity

Abstract

The COVID-19 pandemic has created a high demand on personal protective equipment, including disposable N95 masks. Given the need for mask reuse, we tested the feasibility of vaporized hydrogen peroxide (VHP), ultraviolet light (UV), and ethanol decontamination strategies on N95 mask integrity and the ability to remove the infectious potential of SARS-CoV-2. FIT test data showed functional degradation by both ethanol and UV decontamination to different degrees. VHP treated masks showed no significant change in function after two treatments. We also report a single SARS-CoV-2 virucidal experiment using Vero E6 cell infection. We hope our data will guide further research for evidenced-based decisions for disposable N95 mask reuse and help protect caregivers from SARS-CoV-2 and other pathogens.

Rapid Review of SARS-CoV-1 and SARS-CoV-2 Viability, Susceptibility to Treatment, and the Disinfection and Reuse of PPE, Particularly Filtering Facepiece Respirators

“…Strap strength was unaffected by 10 UVGI cycles (total applied dose 10,000 mJ/cm 2 ), but 20 cycles (20,000 mJ/cm 2 ) affected the material integrity of straps in certain models [ 51 ]. In other studies, applied UVC doses of 10,000 mJ/cm 2 had negligible effects on two N95 FFR models tested (e.g., particle filtration, polymer structure, and tensile strength) [ 85 ], and ~18,000 mJ/cm 2 reduced fit scores of three N95 FFR models but which still remained within the required performance range [ 42 ] ( Table 6 ).…”

“…These can be characterized as: (1) energetic methods (e.g., ultraviolet, dry and moist heat, and microwave generated steam), or (2) chemical methods (e.g., alcohol, ethylene oxide, bleach, and vaporized hydrogen peroxide). Some of these rapidly and markedly affect N95 particle filtration performance (alcohol [ 22 , 41 , 42 , 43 , 44 ]), while others require chemical supplies and/or specialized facilities (e.g., ethylene oxide and vaporized hydrogen peroxide), or are not readily scalable to large numbers of PPE (e.g., microwave generated steam). Therefore, the focus of this review is on methods that may be easy to implement rapidly at large scale.…”

“…Heilingloh et al [ 54 ] inactivated SARS-CoV-2 in a liquid medium (>6.7 log 10 reduction) with an applied UVC dose of 1048 mJ/cm 2 ( Table 4 ). Fischer et al [ 39 ], Smith et al [ 42 ], and the unpublished Ozog et al [ 56 ] studied inactivation on N95 respirators, and UVGI treatment was not entirely efficacious against SARS-CoV-2. In Ozog et al, not all samples tested achieved a ≥3.8 log 10 reduction with UVC at 1500 mJ/cm 2 , with treatment failure common on FFR straps [ 56 ] ( Table 4 ).…”

“…However, liquid hydrogen peroxide at 3% had minimal viricidal effect against SARS-CoV-2 after 30 seconds of contact [ 74 ]. Chemical disinfection may be suitable for certain hard surfaces and PPE items such as goggles, but is not recommended for FFRs due to loss of filtration performance (e.g., alcohol [ 22 , 41 , 42 , 43 , 44 ]) or residual chemical odor (e.g., hypochlorite [ 77 ]).…”

“…Due to the widespread use of alcohol-based disinfectants, it is important to emphasise that FFRs should not be sprayed with alcohol, as it can remove the electrostatic charge from the respirator filter material, severely reducing the filter’s effectiveness at collecting particles, as shown by a number of studies [ 22 , 41 , 42 , 43 , 44 ].…”