Warming helps N95 face masks is safe to disinfect
N95 face masks have become in times of COVID-19-pandemic, nearly, a warming helps to disinfect the masks effectively, so they can be safely used several times. This could help to prevent infections with the Cornavirus, even if a mask shortage exists.
In the current study, the Stanford University, it was found that by a proper heat disinfection of N95-materials can be ensured. The results of the study were published in the English scientific journal “ACS Nano”.
Warming allowed for safe multiple use of the masks
Due to the lack of N95 face masks, in particular, health care Workers must always wear the same mask. In the investigation of different methods for the disinfection of N95-materials, it was found that their filtration efficiency is in the case of heating above 50 disinfection cycles.
How does it work with N95 masks?
N95 masks contain a layer of polypropylene fibers that form a porous, breathable network. To facilitate the collection of smaller particles, are loaded, the fibers electrostatically. It is so far, different methods, such as, for example, heating, ultraviolet radiation and bleach treatment to disinfect the N95 were recommended masks. This, however, was not studied extensively.
The fabric of N95 masks has been studied
The researchers compared five methods that can be used in a hospital to determine how to hold the mask materials, repeated disinfections stand. For this, they did not use N95 masks, but pieces of the special tissue have been investigated, which is used for the production of the masks.
The Material was treated with different disinfectants
The research group treated the Material with a specific disinfectant, and compared its ability to filter aerosol particles (breathing resemble droplets, but no Coronavirus) before and after disinfection. The Team found so that the Spraying of the tissue with Ethanol or chlorine bleach solution reduced the filtration efficiency after only one treatment drastically.
Ethanol and bleach reduced the filtration efficiency drastically
In the case of a disinfectant with Ethanol, the filtration efficiency decreased from about 96 percent to 56 percent. Bleach reduced, however, the filtration efficiency to 73 percent. A single treatment with steam is continued, the Filtration upright, but five steam treatments led to a sharp drop in the efficiency.
What a ultra-violet irradiation caused?
A UV irradiation allowed for cycles of up to 20 Disinfection. However, the use according to the researcher can be problematic, as the exact UV-dose is difficult to determine. Too little radiation, the Virus kills not enough to damage much radiation the Material of the mask.
The optimal method for disinfection of N95 masks?
The best disinfection method seemed to be the warming. For example, the 20-minute heating at 185 degrees Fahrenheit (85 degrees Celsius) allowed a 50-time treatment of the tissue without loss of filtration efficiency. The frequent Fitting and removal of N95 masks, however, could affect the fit, which also has an effect on the performance, report the researchers. (as)