New study indicates that a N95 Mask Can Be Decontaminated for reuse at least 25 Times

With the enhanced virulence of the Omicron variant, some experts are urging us all to upgrade cloth and surgical masks to the much more protective N95s, but supply remains a concern. The limited supply is why this advice has so far been held back, but a new study may make this more feasible – suggesting N95s can be safely decontaminated many times in a clinical setting.

The study tested to see if these respirators deteriorate after decontamination – a process where the mask is exposed to UV light or vaporized hydrogen peroxide (VHP) to kill any SARS-CoV-2 virus particles that might have stuck around.

While early in the pandemic research indicated that an N95 could be decontaminated and reused a couple of times without being compromised, a new study from a team at Beth Israel Deaconess Medical Center in Boston has now shown that even after 25 rounds of VHP decontamination, the N95 respirator was just as good at fitting on the face and filtrating particles.

N95 respirators are a type of mask fitted very closely to the face to create a seal. To be classed as an N95 respirator, the protective device must meet the US National Institute for Occupational Safety and Health N95 classification of air filtration – which means it filters at least 95 percent of airborne particles.

"Most VHP studies were limited to evaluating decontamination efficacy, respirator filtration after 5-10 cycles, or fit on mannequins," the team writes in their new study. ...

Another recent study published in PLOS One found that dry heat (like the one found in an oven) can also work. At 100 degrees Celsius (212 degrees F), 30 minutes was enough to kill SARS-CoV-2 virus particles but not damage the mask. This team of researchers specifically used a walk-in oven rather than a regular one, with only four types of respirators typically used in large health care facilities, so your results may vary. They also did the method only once, so heat decontamination may not be as long lasting as the VHP decontamination, although more widely available.  ...