In a statement released today, NIH announced the validation of four decontamination methods after a study of the decontamination of small sections of N95 filter fabric exposed to SARS-CoV-2 (the virus that causes COVID-19).
Showing that decontamination can work matters because authorities are increasingly turning to it to boost the supply of N95 masks amid the pandemic. The U.S. Department of Defense, for example, has inked a $415 million contract to provide 60 Battelle Critical Care Decontamination Systems that use vaporized hydrogen peroxide (VHP) to decontaminate as many as 80,000 N95 respirator masks each day for reuse. Steris (NYSE:STE) has an emergency use authorization (EUA) from the FDA for its own vaporized hydrogen peroxide system.
The new study, conducted with NIH’s Rocky Mountain Laboratories in Hamilton, Montana, tested decontamination in the form of VHP, 70 °C dry heat, ultraviolet light and 70% ethanol spray.
All four methods eliminated detectable viable virus from the fabric samples. Investigators also treated fully intact, clean respirators with the same decontamination methods to test reuse durability. After that, RML employees wore the masks for two hours to determine if fit remained and the face stayed sealed, while decontamination was repeated three times for each mask, using the same procedure.
The study found that ethanol spray damaged the integrity of the fit and seal after two sessions and do not recommend its use. UV and heat-treated respirators showed fit and seal problems after three decontaminations, suggesting they can be reused twice. Masks treated with VHP showed no failures, suggesting the potential for three-time reuse.
Normally, N95 respirators are designed for single-use, but the authors of the study concluded that VHP was the most effective decontamination method for allowing more uses, with no virus detected after a 10-minute treatment.
The authors of the study urge anyone decontaminating the N95 respirators to check the fit and seal after each reuse. Their findings are not yet peer-reviewed but are being shared to assist the public health response to coronavirus, according to the NIH statement.
