Masks are a kind of sanitary products. Generally, they are worn on the mouth and nose to filter the air entering the mouth and nose to block harmful gases, odors, droplets, viruses and other substances. They are made of gauze or paper. Masks he a certain filtering effect on the air entering the lungs. When respiratory infectious diseases are prevalent, and when working in dust and other polluted environments, wearing masks has a very good effect. Masks can be divided into air filtering masks and air supply masks