Masks should not be scalded with boiling water. Masks that have been scalded with boiling water are not recommended for use, as this will reduce the protective effect of the mask. The mask is composed of 3 layers, which can block the external droplets, viruses, bacteria and other microorganisms. If it is scalded with boiling water or sprayed with alcohol, it will affect the protective effect of the mask. Because it will affect the fiber structure of the mask, causing the holes to become larger and not conducive to the protective effect of the mask. Therefore, whether it is a medical surgical mask or N95 mask, the filtering effect of the mask will be reduced after being sterilized by hairdryer, water steam or ultraviolet lamp. So when you go out to wear a mask, it is recommended that each time 4 hours to replace 1 time, usually wash your hands and open the window more ventilation.