1. Respiratory infectious diseases are not only transmitted through the respiratory tract;

2. Preventive measures should precede exposure;

3. The tight structure and efficient filtering of the mask will increase breathing resistance and reduce comfort;

4. If the mask design is not suitable for the user’s face shape, it will affect the suitability and will cause leakage;

5. Under the requirements of suitability and correct use, the protective mask can effectively reduce the concentration of harmful substances by 90%;

6. The government has not established safe exposure limits for pathogenic microorganisms. Respiratory protection can only reduce the risk of disease, but it cannot eliminate the risk.