How to distinguish the front and back of a mask?

How to distinguish the front and back of a mask?
When wearing it, the blue face is outward and the white face is inward, that is, the white face is the side facing the mouth.

According to the degree of smoothness, the outer surface of the mask is mostly smooth because of its water blocking function; the inner layer is mostly made of materials with good breathability, close to the skin, which is conducive to breathing, more delicate, and comfortable.

Notes on wearing a mask:

1. Wash your hands before wearing a mask.

2. When wearing a disposable medical mask, fully fold the folded face, wrap the mouth, nose, and mandible completely, and then press the nose clip tightly so that the mask fits the face completely.

3. After wearing the mask, try not to touch the mask. If you must touch, remember to wash your hands before and after touching.

4. When removing the mask, try not to touch the outside of the mask. Remember to wash your hands immediately after removing the mask.