Coronavirus: 4 Methods Effective in Decontaminating N95 Respirator Masks

With supplies of N95 respirator masks stretched thin during the coronavirus pandemic, decontamination of used masks can help meet demand.

Based on a review of scientific literature, there are four effective methods to decontaminate N95 respirator masks, a recent research article says.

During the coronavirus pandemic, maintaining adequate supplies of personal protective equipment (PPE) for healthcare workers has been an acute pain point. With the virus primarily spread through respiratory droplets and aerosol particles, N95 masks have been in high demand and limited supply. In March, the U.S. Department of Health and Human Services estimated that a prolonged pandemic would require 3.5 billion N95 masks but only 35 million were stocked.

Treating coronavirus disease 2019 (COVID-19) patients without adequate PPE is potentially deadly for healthcare workers. In Italy, which faced shortages of PPE and other critical pandemic resources such as ventilators in the early stage of the pandemic, about 20% of healthcare workers became infected.

To ensure adequate supplies of N95 masks, decontamination of the respirators has become a matter of necessity at many healthcare facilities. The recent research article, which was published in JAMA Otolaryngology—Head & Neck Surgery, identifies four decontamination methods that can recycle N95 masks without compromising the fit of the masks or the filtering material.

1. Ultraviolet germicidal irradiation

In a 2018 study, researchers used ultraviolet light to process 15 different N95 mask models contaminated with the H1N1 influenza virus. The ultraviolet germicidal irradiation significantly reduced virus viability in 12 of the 15 models.

In an April 2020 study, ultraviolet germicidal irradiation of N95 masks was effective over three rounds of decontamination. However, the researchers found that the UV light treatment process required more time than other decontamination methods.

In a 2009 study, exposing respirator masks to UV light for 30 minutes was found to be an effective decontamination method.

2. Vaporized hydrogen peroxide

The 2009 study also found vaporized hydrogen peroxide treatment effective in decontaminating respirator masks. In that study, researchers exposed contaminated masks to vaporized hydrogen peroxide for 55 minutes.

3. Steam treatment

In a 2012 study, microwave-generated steam and oven-generated steam were found effective in treating N95 masks contaminated with H5N1 influenza virus in droplet form.

In a Stanford Medicine study, treating N95 masks with boiling water vapor for 10 minutes was found to be an effective decontamination method for Escherichia coli bacteria.

4. Dry heat treatment

The Stanford Medicine researchers also found dry heat effective in treating N95 masks contaminated with Escherichia coli bacteria. The masks were exposed to dry oven heating at 70°C for 30 minutes.

Low-resource decontamination option

For healthcare facilities that lack the resources to adopt active decontamination methods for N95 masks such as UV light or steam heating, "time decontamination" is a viable alternative, the JAMA Otolaryngology—Head & Neck research article says.

In time decontamination, healthcare workers use an N95 mask, then store the mask in a time-stamped paper bag for reuse. "Since the surface viability of the novel coronavirus is presumed to be 72 hours, rotating N95 respirator use and allowing time decontamination of the respirators is also a reasonable option," the research article says.

If time decontamination is utilized to reuse N95 masks, the Centers for Disease Control and Prevention recommends that masks should be out of service for five days.