The mask cannot be cleaned and disinfected, and if it cannot be used again after cleaning and disinfection, it will not be able to play a protective role. Medical surgical masks and medical N95 masks rely on the “filter layer” to adsorb and block viruses and other micro-particles (aerosols), thus playing a role in the prevention of new coronavirus pneumonia. The “filter layer” is mainly composed of polypropylene meltblown microfiber, if cleaned and disinfected, it will make the charge in the filter layer disappear rapidly, resulting in a significant decrease in filtration effect. And the outer surface of the mask are “water-repellent treatment”, alcohol, water, blood, saliva, etc. are very difficult to penetrate, can play a protective role. But if the cleaning and disinfection will destroy the outer surface layer, it will make the mask lose the protective effect.