1. Aerosol transmission: droplets are mixed in the air to form an aerosol, which causes infection after inhalation.

How long the aerosol can be suspended in the air, I have not found an authoritative interpretation. What can be determined is that it is different according to the sunshine, wind speed and humidity of the environment. Can survive for at least 10 minutes to several hours. This means that you need to go through the elevator, stairs, or corridors. If an infected person sneezes there a few minutes ago, it may cause you to be infected. If an infected person sneezes a few hours ago, the possibility of being infected cannot be completely ruled out.

2. Paper masks, cotton masks, sponge masks, activated carbon masks useless

3. Medical surgical masks clearly indicated in the "outer packaging" prevent respiratory infections to a certain degree.

I believe that until now, there must still be some people in the unknown who have been rhythmized by some ignorant, unscrupulous and irresponsible media. I thought that as long as I wore a mask, everything would be fine, and I could go out casually. It must have nothing to do with viruses. The facts are far from it. Basically, non-medical masks have little protection. Even medical surgical masks are not 100% protective. But it can definitely reduce the chance of infection.

As for the legendary N95 mask, and whether you can buy it or not, even if you really wear the N100, or even a higher level P100, there is still a long distance from absolute safety.

In the process of panic buying in masks, many people often overlook a protective measure that is even more important than masks: wash your hands! Maybe you wash it every time you go home, but how to wash it, how long to wash it, whether you can clean every position. I am afraid that many people are difficult to guarantee.