1, the correct way to wear the mask is that the outside is blue. Generally speaking, masks of different colors are colored on the outside, such as blue, pink, purple, etc., and the white side faces inward and clings to our faces. Not only that, the mask is divided into upper and lower parts, and the side with metal strips inside is the upper end, which is close to the bridge of the nose when worn.

2. The blue medical mask is generally composed of a mask body and a tension band. The mask body is divided into three layers, the inner layer is made of skin-friendly materials, the middle layer is made of isolation filter layer, and the outer layer is made of special materials. This kind of high-efficiency medical mask is hydrophobic and breathable, and has obvious filtering effect on tiny aerosol with virus or harmful dust, but it can't effectively filter PM 10 and PM2.5. The overall filtering effect is good, and the materials used are nontoxic and harmless and comfortable to wear.

3, masks should not be worn for a long time. Because the blood circulation of human nasal mucosa is very strong, the passage in nasal cavity is very tortuous, and nasal hair constitutes a "barrier" for filtration. When air is inhaled into the nostrils, the airflow forms a vortex in the tortuous channel, which warms the airflow inhaled into the nasal cavity. If you wear a mask for a long time, it will make the nasal mucosa fragile and lose the original physiological function of the nasal cavity, so you can't wear a mask for a long time.

4. Masks can only be worn in special circumstances, such as places where there are many people and the air is not circulating. Of course, you need to wear a mask when walking in the wild, in order to prevent wind, sand and cold, or to move in an air-polluted environment, but the time should not be too long.