n fact, there are two standard classifications for masks: 1. According to the filtering effect; 2. According to the environment and function

In this paper, three criteria are simply put forward according to the filtration effect

N series: protection of non oily suspended particles, filtration 95%, time unlimited (common such as N95).

R Series: protect non oil suspended particles and sweat oil suspended particles, filtration 99%, aging 8 hours.

P Series: protection of non oil suspended particles and sweat oil suspended particles, filtration 99.97%, aging without time limit.

Today, we will focus on the daily classification by function and use

The first category: Cotton Mask [used to keep warm in winter, can't be used as anti-virus mask, the aging is 0]

The second category: medical masks [can prevent the bacteria from breathing in, the flow of people is not large, and there are more places to use. Because of the poor veneer, it is not suitable for the severe area, and the time limit is 4-6 hours at a time]. It is not good to throw away the masks.

The third category: activated carbon masks [activated carbon can prevent bacteria, dust and odor, but poor air permeability, can not be worn for a long time, afraid of hypoxia, anti-virus ineffective, timeliness once a day, high concentration of 4-6 hours to replace]

The fourth category: dust masks [usually with breathing valve, good facial fit, can be used as anti-virus masks, but the breath valve exhaled with virus gas will still infect other people. Although the masks themselves are disposable, this can be used several times, and the medical and nursing staff can replace them at one time]

Category 5: N95 or above masks [n series, R series and P series are all OK. If there is no pollution and no damage, it can be reused. If conditions permit, it can not exceed 3 days, please leave this kind of mask for medical staff]