The team found that spraying the fabric with an ethanol or chlorine bleach solution drastically reduced the filtration efficiency after only one treatment, from about 96% to 56% (ethanol) or 73% (bleach).
A single steam treatment maintained filtration, but five steam treatments led to a sharp decline in efficiency. 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, the researchers note. The best disinfection method appeared to be heating. For example, heating at 185 F for 20 minutes allowed the fabric to be treated 50 times without loss of filtration efficiency. But frequently donning and removing N95 masks could affect fit, which also impacts performance, the researchers point out.
