1. Try to buy masks that are packaged and have the "LA" (labor protection) logo or both the "LA" and "QS" logos on the package.

2. When purchasing, pay attention to the identification of the product to check whether the product name, production date, factory name, factory address, shelf life, product instruction manual, etc. are clearly marked.

3. The filter material used in masks has generally undergone a very complicated process, which is a one-time use product and is not suitable for washing.

4. Masks with different face shapes-different designs of masks may not be suitable for everyone. Some people wear it tightly, and some people may not fit it tightly. Therefore, before using a certain type of mask for the first time, refer to the instructions and try it on first. Even if the use environment, product characteristics and other factors are considered, the product may be inefficient or even invalid because it is not suitable for the user.