The most frequently mentioned masks now include KN95, N95, medical surgical masks and so on.

The first is KN95 masks. According to the classification of the national standard GB2626-2006 "Respiratory Protective Equipment Self-priming Filter Type Anti-Particulate Respirator", masks are divided into KN and KP according to the efficiency level of the filter element. KP type is suitable for filtering oily particles, KN ​​type is suitable for filtering non-oily particles. Among them, when the KN95 mask is detected with sodium chloride particles, its filtration efficiency should be greater than or equal to 95%, that is, the filtration efficiency of non-oily particulates above 0.075 microns is greater than or equal to 95%.

The N95 mask is one of the nine particulate protective masks certified by NIOSH (National Institute of Occupational Safety and Health). "N" means not resistant to oil. "95" means that when exposed to a specified number of special test particles, the particle concentration inside the mask is more than 95% lower than the particle concentration outside the mask.

Then there are medical surgical masks. According to the definition of YY 0469-2004 "Technical Requirements for Medical Surgical Masks", medical surgical masks are "worn by clinical medical staff in an invasive operating environment to provide protection for patients undergoing treatment and medical staff performing invasive operations, and prevent Medical surgical masks spread by blood, body fluids and splashes are masks worn by medical staff at work.” This type of mask is used in medical environments such as medical clinics, laboratories, and operating rooms, and is divided into a waterproof layer, a filter layer, and a comfort layer from the outside to the inside.