Decontaminating N95 Respirator Masks after SARS-CoV-2 Exposure

Excerpts and edited notes for this blog were referenced from a post by Perio Implant Advisory written by Dr. Scott Froum, DDS on September 1st, 2020, who examined the results from a new study that looked at four decontamination methods on N95 respiratory mask filter fabric that had been exposed to SARS-CoV. The following blog is presented for viewers to validate, accept and/or decline its content and findings on their own.

The COVID-19 pandemic has created a shortage of N95 respirators worldwide in both the medical and dental fields. Because N95 respirator masks are designed for one use only prior to disposal, concern has arisen over the forced need for health-care workers to use these masks for multiple patients and extended periods of time (hours, days, and sometimes weeks).

N95 decontamination methods have been described in the literature for bacterial spores, bacteria, and influenza A with regard to filtration efficiency and seal, but not the virus that causes COVID-19, SARS-CoV-2.1 Studies on various decontamination methods have shown adverse effects on both filtration and seal of N95 respirator masks, causing them to become ineffective after decontamination.2

A new study in the Journal of Emerging Infectious Diseases looked at four decontamination methods on N95 filter fabric that had been exposed to SARS-CoV-2.3 The decontamination methods included vaporized hydrogen peroxide, dry heat at 70 degrees Celsius (158 degrees Fahrenheit), ultraviolet light (UV-C), and 70% ethanol spray. Although all four methods eliminated detectable viruses from the N95 fabric, they altered the filtration and seal in different ways.

Researchers found that vaporized hydrogen peroxide was the most effective decontamination method and killed all detectable viruses after 10 minutes, without affecting integrity of the mask fabric for use up to three times. UV-C light needed 60 minutes of exposure to the mask to kill all detectable viruses, with similar effects on mask integrity (use up to two or three times). Dry heat needed 60 minutes of exposure to mask fabric to kill all viruses, with effects on mask integrity after two uses. Lastly, 70% ethanol could kill all detectable viruses but affected the integrity of the mask after one use.

In conclusion, vaporized hydrogen peroxide and UV-C light allowed N95 respirator masks to function for three uses, while dry heat allowed two uses. 70% ethanol was not recommended. The authors finished by stating that anyone decontaminating an N95 respirator mask should carefully check the fit and seal over the face before each reuse.