In the case of shortage of masks, medical surgical masks and N95 masks can be used repeatedly and can be used for a longer period of time when they are not broken and not contaminated, but they cannot be reused after boiling. The material of the mask filter layer usually undergoes “electret treatment”, so that it carries a trace of electric charge to ensure that it can effectively adsorb various particles in the air. The entry of water will make the charge in the filter layer disappear rapidly, resulting in a significant decrease in the filtering effect. At the same time, the filter layer of the mask is not resistant to high temperature, the temperature is greater than 80 ℃ will shrink deformation, resulting in structural damage, so that the protection effect is reduced.