You should buy N95 masks, medical surgical masks, masks with valves, etc. These masks have played a strong role in blocking bacteria and preventing virus invasion, which can block more than 50% of bacterial invasion. However, you should wear a new mask in time.

How long is the shelf life of the mask?

The shelf life of unopened disposable medical masks is generally 2-3 years from the date of production. It is not recommended to continue wearing a mask beyond the shelf life.

Before wearing a mask, carefully check the shelf life of the mask for damage and pollution. The protective ability of masks will decrease with the increase of use times, so it is best not to reuse them.

You can't wear a mask alternately on both sides, because the outer layer of the mask will accumulate a lot of pollutants such as dust and bacteria in the outside air.