Coronavirus outbreak: Study reveals heating N95 face mask disinfects it to reuse

Los Angeles, May 06: Heating may be the best way to disinfect N95 masks for reuse, according to a study which found that doing so preserves their filtration efficiency for 50 cycles.

Since the outbreak of the novel coronavirus pandemic, N95 face masks have been in short supply, said the researchers, including those from Stanford University in California, US.

According to the researchers, due to shortage of face masks, many have to wear the same mask repeatedly. The study, published in the journal ACS Nano, tested several methods for disinfecting N95 materials, finding that heating them preserves their filtration efficiency for 50 cycles of disinfection.

The researchers noted that N95 face masks contain a layer of "meltblown" polypropylene fibres that form a porous, breathable network. To help capture smaller particles that could slip through the holes, the fibres are electrostatically charged, they said.

The US Centers for Disease Control and Prevention has recommended several methods for disinfecting N95 face masks, such as heating, ultraviolet (UV) radiation and bleach treatment. However, so far these methods have not been tested extensively, especially for multiple rounds of disinfection, they said.

The researchers wanted to compare five of the methods that could reasonably be used within a hospital setting to see how mask materials hold up to repeated disinfection.

UV radiation allowed up to 20 cycles of disinfection, however, administering the exact dose of UV that kills the virus without damaging mask materials could be problematic, they also said.

The researchers said best disinfection method appeared to be heating. For example, heating at 85 degrees Celsius for 20 minutes allowed the fabric to be treated 50 times without loss of filtration efficiency.

However, frequently donning and removing N95 masks could affect fit, which also impacts performance, the researchers said.