N95 respirators can be decontaminated effectively and maintain functional integrity for up to three uses, according to National Institutes of Health scientists.
Exposing contaminated N95 respirators to Vaporized Hydrogen Peroxide or ultra violet radiation is proposed to eliminate the SARS-Cov2 virus from the material while maintaining the integrity of the masks. Such masks appears to be fit for up to 3 uses.
The study was conducted in a controlled laboratory setting. The findings are not yet peer-reviewed but are being shared to assist the public health response to COVID-19.
Researchers tested the decontamination of small sections of N95 filter fabric that had been exposed to SARS-CoV-2, the virus that causes COVID-19.
METHODS USED FOR DECONTAMINATION:
The following methods of decontamination were studied:
- UV radiation (260-285 nm)
- Dry heat (70 degree celcius)
- Ethanol spray (70%)
- Vaporized hydrogen peroxide
All four methods eliminated detectable viable virus from the N95 fabric test samples.
EFFICACY OF TECHNIQUES:
The scientists found that 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 — suggesting these respirators potentially could be re-used twice.
The VHP-treated masks experienced no failures, suggesting they potentially could be re-used three times.
SHORTCOMINGS OF THE STUDY:
It tested the masks for only 2 hours, whereas in clinical practise, they are being worn for much longer period of time.
After the study is peer reviewed, the Centres for Disease Control and Prevention may update its recommendations.
Researchers concluded that VHP was the most effective decontamination method, because no virus could be detected after only a 10-minute treatment. UV and dry heat were acceptable decontamination procedures as long as the methods are applied for at least 60 minutes.
Researchers have requested anyone decontaminating an N95 respirator to check the fit and seal over the face before each re-use.