N95 is the certification level of American respirators, certified by the National Institute of Occupational Safety and Health (NIOSH). This type of mask can filter out more than 95% of non-oily particles (aerosol) under the specified air flow (85L/min), so it is named N95. And if it can filter more than 99% of the particulate matter (aerosol), it is called an N99 mask. In addition, corresponding to N95, KN95 is a respirator certified by my country's GB2626-2006 self-priming filter particulate respirator standard for respiratory protection products.
The protection levels of KN95 and N95 masks are equivalent, but they follow the testing standards of different countries. The KN95 mask follows the Chinese standard, and the N95 mask follows the American standard. Both of them have a protection efficiency of not less than 95% for non-oily particles (sodium chloride particles for experimental use).
Can KN95 masks be used for first-line protection?
Both KN95 masks and N95 masks include medical and non-medical types. Among them, KN95/N95 masks with the "medical" mark can be used for front-line protection of medical staff during the anti-epidemic period. Masks without the "medical" mark are not recommended for medical staff and ordinary people can use it. Respirators that conform to GB19083 and above level 1 can not only achieve 95% filterability, but also prevent liquid penetration, and can be used for various operations in medical institutions.
The batch of KN95 masks that the Hubei Red Cross raised doubts this time, if the content of the publicity is true, after checking with the health department, it is confirmed that the product cannot be used for the protection of first-line medical staff in designated hospitals for the treatment of new coronary pneumonia. Non-medical category.
Why can KN95/N95 masks prevent viruses?
Viruses usually do not exist alone in the air, but are attached to particles such as droplets, dust, dander, etc. The filtration mechanism of KN95 and N95 masks is to block these fine particles through the high-performance filter layer in the mask, and build a Protective barrier.
Therefore, when wearing KN95/N95, that is, self-priming filter type anti-particulate respirator masks for respiratory protective equipment, pay attention to the tightness, and should be close to the face, and never leave a "convenience door" for viruses and bacteria. It is recommended to use the belt with caution. There are "exhalation valve" masks.

What is the difference between medical and non-medical masks in KN95/N95 masks?
Jin Xiangyu: The main difference is that the outer surface of medical masks is hydrophobically treated. The medical surgical masks of GB19083-2010 and YY0469-2011 clearly put forward the requirements of "synthetic blood penetration", and the parameter index of "surface moisture resistance" clarifies the medical treatment. The protective effect of protective masks on blood, body fluids and other liquids. In layman's terms, it is like water droplets falling on a lotus leaf. The liquid cannot be soaked on the surface of the mask. This can block the medical staff from frequent contact with alcohol, blood, etc., and prevent it from quickly penetrating; rather than the medical type KN95 /N95 masks will not undergo this special treatment.
The most protective function of KN95 and N95 protective masks is the filter layer. The filter layer is made of polypropylene melt-blown microfiber electret material. The outer surface of the mask has not been treated with hydrophobic treatment. The material will be destroyed by contact with water, alcohol, etc. during application. The structure of the filter greatly reduces the filtering effect. What's more, the blood often contains bacteria, viruses, etc., and the application scenarios of the hospital determine that the medical staff will be exposed to the patient's blood environment with a high probability. Therefore, the hydrophobic treatment of the surface of the medical mask is essential. However, ordinary people are unlikely to encounter alcohol and blood. As long as they change their masks regularly, it will be harmless if they do not undergo this treatment on the outside.