Here Are the Best Ways to Decontaminate N95 Respirators for Reuse

Some pharmacists must use N95 respirators because of close contact with potentially infected people, but, with a shortage of the devices, reuse is critical during the COVID-19 pandemic. What is the best way to decontaminate the devices without damaging the fit and seal? A new NIH study suggests the most optimal alternatives.

HAMILTON, MT – Pharmacists whose activities require them to use N95 respirators might be interested to know that the devices can be decontaminated effectively and maintain functional integrity for up to three uses, according to National Institutes of Health scientists.

N95 respirators are designed for single-use and are worn by healthcare providers to reduce exposure to airborne infectious agents, including the virus that causes COVID-19. 

The national Centers for Disease Control and Prevention has issued guidance on personal protective equipment for pharmacy staff conducting COVID-19 testing and other close-contact patient care procedures, such as influenza and strep testing, where they could be infected by coughing and sneezing.

Public health officials advise that pharmacy staff using respirators must be familiar with proper use and follow a complete respiratory protection program that complies with OSHA Respiratory Protection standard (29 CFR 1910.134). Staff should also have training in the how to put on and remove PPE, the CDC notes.

The NIH study was conducted in a controlled laboratory setting, and the results were posted on the medRxiv website. That is a preprint server which posts articles that have not yet been peer-reviewed but are being shared to assist the public health response to COVID-19. 

The study investigators are with NIH’s Rocky Mountain Laboratories (RML) in Hamilton, MT, and are part of the National Institute of Allergy and Infectious Diseases (NIAID). With collaborators from the University of California, Los Angeles, they tested the decontamination of small sections of N95 filter fabric that had been exposed to SARS-CoV-2, the virus that causes COVID-19. 

“The unprecedented pandemic of SARS-CoV-2 has created worldwide shortages of personal protective equipment, in particular respiratory protection such as N95 respirators,” the investigators write. “SARS-CoV-2 transmission is frequently occurring in hospital settings, with numerous reported cases of nosocomial transmission highlighting the vulnerability of healthcare workers. In general, N95 respirators are designed for single use prior to disposal. Here, we have analyzed four readily available and often used decontamination methods: UV, 70% ethanol, 70C heat and vaporized hydrogen peroxide for inactivation of SARS-CoV-2 on N95 respirators. Equally important we assessed the function of the N95 respirators after multiple wear and decontamination sessions.”

Researchers tested decontamination methods including vaporized hydrogen peroxide (VHP), 70-degree Celsius dry heat, ultraviolet light, and 70% ethanol spray. All four methods were found to eliminate detectable viable virus from the N95 fabric test samples.

Investigation than applied the same decontamination methods to fully intact, clean respirators in an effort to determine reuse durability. To do that, volunteer employees wore the masks for two hours; proper fit and seal was measured after three decontamination procedures.

Results indicate that ethanol spray damaged the integrity of the respirator’s fit and seal after two decontamination sessions and is, therefore, not recommended for decontaminating N95 respirators. Fit and seal problems occurred after three decontaminations with UV and heat-treatment, leading to the suggestion that those respirators could be re-used twice. On the other hand, the VHP-treated masks experienced no failures, suggesting they potentially could be re-used three times.

VHP was the most effective decontamination method, because no virus could be detected after only a 10-minute treatment, the authors conclude, although UV and dry heat were considered acceptable decontamination procedures as long as the methods are applied for at least 60 minutes.

The authors also urge pharmacists and other users decontaminating an N95 respirator to check the fit and seal over the face before each re-use.

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