Ordinary cloth masks, thermal masks and masks used for more than three days do not have the function of safety protection. Cloth masks and thermal masks play a very small role in blocking bacteria and preventing virus invasion, because masks with protective functions need professional medical fabrics. How long is the shelf life of masks? The shelf life of unopened disposable medical masks is generally 2-3 years from the date of production. Masks beyond the shelf life are not recommended to be worn.
Before wearing the mask, check the shelf life of the mask and whether there is damage and pollution. It is best not to reuse the mask, because its protection ability will decrease with the number of times of use.
The two sides of the mask cannot be worn alternately, because the outer layer of the mask will accumulate a lot of dust, bacteria and other pollutants in the outside air. （ShenMeKouZhaoBuJuBeiAnQuanFangHuZuoYong）