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Exposing infected N95 respirators to vaporized hydrogen peroxide (VHP) or ultraviolet (UV) light appears to eliminate the SARS-CoV-2 infection from the material and preserve the integrity of the masks’ fit for approximately three uses, a National Institutes of Health (NIH) research study reveals.
Dry heat (70 ° C) was likewise found to get rid of the virus on masks but was efficient for 2 usages instead of three.
Robert Fischer, PhD, with the National Institute of Allergy and Infectious Diseases in Hamilton, Montana, and coworkers posted the findings on a preprint server on April 15. The paper has actually not yet been peer examined.
Four Techniques Evaluated
Fischer and coworkers compared 4 approaches for decontaminating the masks, which are designed for one-time use: UV radiation (260– 285 nm); 70 ° C dry heat; 70% ethanol spray; and VHP.
For each method, the scientists compared the rate at which SARS-CoV-2 is inactivated on N95 filter material to that on stainless-steel.
All 4 approaches eliminated noticeable SARS-CoV-2 virus from the fabric test samples, though the time required for decontamination varied. VHP was the quickest, needing 10 minutes. Dry heat and UV light each required around 60 minutes. Ethanol required an intermediate amount of time.
To test sturdiness over 3 usages, the scientists dealt with undamaged, tidy masks with the very same decontamination approach and evaluated function through quantitative fit screening.
Volunteers from the Rocky Mountain lab wore the masks for 2 hours to test fit and seal.
The scientists found that masks that had actually been decontaminated with ethanol spray did not operate effectively after decontamination, and they did not recommend use of that method.
By contrast, masks decontaminated with UV and VHP might be consumed to 3 times and function appropriately. Masks decontaminated with dry heat could be used two times prior to function declined.
“Our outcomes indicate that N95 respirators can be decontaminated and re-used in times of scarcity for up to three times for UV and HPV, and up to two times for dry heat,” the authors write. “However, utmost care ought to be provided to ensure the proper functioning of the N95 respirator after each decontamination utilizing readily offered qualitative fit screening tools and to guarantee that treatments are performed for enough time to attain wanted risk-reduction.”
Reassurance for Clinicians
The results will reassure clinicians, much of whom are currently utilizing these decontamination techniques, Ravina Kullar, PharmD, MPH, a transmittable disease specialist with the Infectious Diseases Society of America, told Medscape Medical News.
Kullar, who is likewise an accessory faculty member at the David Geffen School of Medicine of the University of California, Los Angeles, stated the most commonly used techniques have actually been UV light and VPH.
UV light has actually been used for years to decontaminate spaces, she stated. She also stated that so far, products of hydrogen peroxide are sufficient.
An imperfection of the research study, Kullar stated, is that it evaluated the masks for only 2 hours, whereas in scientific practice, they are being worn for a lot longer periods.
After the research study is peer reviewed, the Centers for Illness Control and Avoidance (CDC) might update its suggestions, she stated.
So far, she kept in mind, the CDC has not approved any technique for decontaminating masks, “however it has stated that it does not challenge utilizing these sterilizers, disinfectants, gadgets, and air purifiers for successfully eliminating this infection.”
Safe, numerous usage of the masks is crucial in the COVID-19 crisis, she stated.
“We need to take a look at other systems to keep these N95 respirators in use when there’s such a scarcity,” she stated.
Stability of the fit was an important consider the study.
“All health care employees need to go through a fitting to have that mask fitted properly. That’s why these N95s are only authorized for health care specialists, not the ordinary public,” she said.
The research study was supported by the National Institutes of Health; the Defense Advanced Research Study Projects Company; the University of California, Los Angeles; the United States National Science Structure; and the US Department of Defense.
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