There are many kinds of masks, among which the cotton mask is actually one of the most common ones. Cotton masks are mainly made of cotton, the characteristics of cotton itself determines its gap and density is relatively limited. Can only filter larger particles, for tiny particles, such as PM2.5 fine particles, cotton filtering effect is very weak. Now the purpose of wearing masks is to filter viruses and bacteria, to play the role of disease prevention. But the cotton filtering effect is relatively limited, there are a lot of viruses and bacteria may be inhaled into the respiratory tract through the gaps in the cotton, and can not play a role in preventing disease. Therefore, if you wear cotton wearing masks should pay special attention to the choice of the activity environment, must choose a relatively clean live activity environment, simple activity environment. To maintain a sufficient effective distance with the surrounding people, at least 1-2 meters above, so as not to bring risks because of the poor filtering performance of the mask. Content source: Dr. Yurai