KN95 masks refer to the domestic standard N95 masks, which can theoretically defend 95% of particles above 0.3μm, and more than enough to defend droplet particles up to 5μm in diameter. masks above the N95 level can theoretically be used for 1-2 days, but many disposable medical N95 masks, as long as they are taken off, cannot be reused, which is relatively wasteful. Because the cost and price of N95 masks are relatively high, you can usually use disposable surgical masks for protection. The total wearing time of disposable surgical masks can be up to 4 hours, but they need to be replaced immediately if they come into contact with liquids afterwards. If you are going to enter or leave relatively dangerous places, or as a health care worker, you should wear a medical N95 mask, and the mask should also be disposed of as medical waste. Theoretically these masks can only be used once and cannot be reused. Content source: Dr. You Lai