N95 masks are not washable. the material of the filter layer of N95 masks usually undergoes “electret treatment”, so that it carries a trace charge to ensure that it can block more than 95% of the 0.3μm size particles from spreading, which is also the key to N95 masks being able to prevent new coronaviruses. If washed, the entry of water will cause a rapid loss of charge in the filter layer, resulting in a significant decrease in filtration, leading to a reduction in the protective effect of the mask or even loss. If masks are in short supply, the public can extend the use of N95 masks when they are not broken or contaminated, but it is not recommended to wash, heat, spray alcohol and any other special operations on the masks.