I've just heard about the "Battelle sterilisation method"..which consists of using Hydrogen Peroxide vapour under pressure to sterilise used masks so that "they can be reused up to 20 times"..Hydrogen Peroxide does indeed sterilise, I use it in a solution ( hand wash and equipment wash#,  in the hand wash it is mixed in along with an 80% alcohol solution and a liquid soap surfactant and chlorhexidine and another combination of disinfectants*, available commercially and cheaply, proven to be 99.5