The kf94 mask protects against viruses. KF94 is a standard for masks set in Korea. The mask can effectively block droplets with a diameter of about 1~4μm, and particles with a diameter of 0.4μm. It can prevent droplets or particles carrying viruses from directly contacting the human respiratory tract to the maximum extent possible. It is suitable for environments with heavy air pollution and viruses. But because KF94 is not a needle medical mask, so the bacterial filtration rate did not set standards, and anti-spatter is not as good as medical, once contaminated with droplets, the risk of infection is still relatively high. Usually KF94 masks have a time limit of 48 hours, and prolonged use of the mask will significantly reduce its filtration and protection functions. If you are going to a sparsely populated area or a place where there is no new coronavirus, you can use the KF94 mask temporarily. If you are in a contaminated environment for a long period of time, it is recommended to change the mask once every 4-8 hours.