Study warns some decontamination methods damage N95 face masks

A number of decontamination systems have been granted Emergency Use Authorization status by the FDA to increase the number of N95 face masks available to healthcare workers. A notable shortage in these masks forced rationing and, in many cases, reuse of the used masks, something decontamination systems aim to improve by killing any pathogens on the material. A new study warns that some of these systems are actually damaging the masks.

Unlike paper masks and reusable fabric masks, an N95 face mask is used by healthcare workers during particularly risky procedures — ones that can aerosolize droplets containing virus particles that may then be inhaled by the worker. These masks are vitally important for protecting these healthcare workers, but they were and, in some places still are, in short supply.

This shortage spurred the development of different decontamination methods designed to make these typically disposable masks reusable. A new study out of the University of Massachusetts Amherst found that while some of these methods didn't negatively impact how well the mask functioned, others may cause 'substantial damage' to treated N95 masks.

As expected, damage to the mask can make it less effective, putting anyone who uses it at risk of infection. This puts workers in a very unfortunate position during the pandemic, with study lead author Richard Peltier explaining:

Given the global N95 shortages, clinicians face a choice: wearing a used, and potentially infected respirator, or wearing one that was decontaminated through a process that may affect the integrity of the respirator.

The study found that using high concentrations of gas plasma hydrogen peroxide (gpHP) and ultraviolet germicidal irradiance can impair the function of these masks over time, whereas masks treated up to 10 times with vaporized hydrogen peroxide and up to five times with short-duration gpHP were able to filter particles at their original levels. Some other decontamination systems are being used, as well, that haven't yet been studied for potential mask damage.