NIH examines efficacy of N95 respirator reuse

National Institutes of Health (NIH) scientists maintain N95 respirators can maintain functional integrity for up to three uses when decontaminated effectively.

The findings stem from a study conducted in a controlled laboratory setting. The results are not yet peer-reviewed but are being shared to assist the public health response to COVID-19.

Researchers from NIH’s Rocky Mountain Laboratories (RML) in Hamilton, Montana, joined collaborators from the University of California, Los Angeles, in testing decontamination of small sections of N95 filter fabric exposed to SARS-CoV-2, which is the virus that causes COVID-19.

Vaporized hydrogen peroxide (VHP), 70-degree Celsius dry heat, ultraviolet light, and 70 percent ethanol spray were among the tested decontamination methods. Study researchers assessed each of the four methods eliminated detectable viable virus from the N95 fabric test samples.

The investigators then treated fully intact, clean respirators with the same decontamination methods to test their reuse durability.

Researchers indicated ethanol spray damaged the integrity of the respirator’s fit and seal after two decontamination sessions and therefore do not recommend it for decontaminating N95 respirators; UV and heat-treated respirators began showing fit, and seal problems after three decontaminations, which suggested the respirators potentially could be reused twice; and the VHP-treated masks experienced no failures, suggesting they possibly could be reused three times.