N95 respirators can be decontaminated effectively and used up to three times, according to researchers at the University of California Los Angeles.
“Although N95 respirators are designed for just one use before disposal, in times of shortage, N95 respirators can be decontaminated and reused up to three times,” said James Lloyd-Smith, a coauthor of the study and a UCLA professor of ecology and evolutionary biology.
“But the integrity of the respirator’s fit and seal must be maintained,” Lloyd-Smith said.
In a controlled laboratory setting, the researchers tested several decontamination methods on small sections of N95 filter fabric that had been exposed to SARS-CoV-2.
Methods included vaporized hydrogen peroxide, dry heat at 70°C (158°F), ultraviolet (UV) light, and a 70% ethanol spray. All for methods eliminated detectable viable virus traces from the N95 fabric test samples.
The investigators then treated fully intact, clean respirators with the same decontamination methods to test their reuse durability.
Employees with the National Institutes of Health’s Rocky Mountain Laboratories in Montana volunteered to wear the masks for two hours to determine if they maintained a proper fit and seal over the face. The researchers decontaminated each mask three times, using the same procedure with each.
The masks treated with vaporized hydrogen peroxide experienced no failures, suggesting they potentially could be reused three times, Lloyd-Smith said. Those treated with UV light and dry heat began showing fit and seal problems after three decontaminations, suggesting these respirators potentially could be reused twice.
The researchers concluded that vaporized hydrogen peroxide was the most effective method because no traces of the virus could be detected after only a 10-minute treatment. UV light and dry heat also are acceptable, as long as they are applied for at least 60 minutes, the researchers said.
The ethanol spray damaged the integrity of the respirator’s fit and seal after two sessions, and the researchers do not recommend it for decontaminating N95 respirators.
Also, the researchers stressed that anyone decontaminating an N95 respirator should closely check the fit and seal over the face before each reuse.
The study, “Effectiveness of N95 Respirator Decontamination and Reuse Against SARS-CoV-2 Virus,” was published by the Centers for Disease Control and Prevention.