KN95 mask is 3 layer or 5 layer of good?

        How many masks are needed? During the critical period of personal protection, masks are essential for us to travel, but they come in many forms。 First of all, KN95 masks are mainly used to filter non-oily particles, and the number refers to its filtration efficiency, plus the percentage will be clear.  KN95 means that the filtration efficiency of non-oily particulate matter above 0.075 micron is greater than 95%. 

       KN95 masks consist of five layers, with the outermost layer of non-woven fabric treated with water resistance. The second layer is hot air cotton. The third and fourth layers are two layers of electret treated melt-blown cloth. The innermost layer is soft skin-friendly non-woven fabric. Compared with the basic protection of other masks used in life, KN95 masks can give people better protection. 

   According to the Notice on The Issuance of Protective Guidelines for People at Different Risk of Novel Coronavirus Infection and guidelines on the Use of Pneumonia Masks to prevent Novel Coronavirus Infection, KN95 and above particulate matter protective masks are: The protective effect is better than that of surgical masks and disposable medical masks. It is recommended for field investigation, sampling and testing personnel, and the public can also wear it in crowded places or closed public places.

        The specific situations of wearing KN95 and above particulate matter protective masks include: in crowded public transportation places and on transportation vehicles; Do not touch or adjust the mask when entering the living space of the person under home quarantine. When investigating suspected and confirmed cases; For environmental cleaning and disinfection personnel, corpse disposal personnel. 

        In addition, for the public transport passengers, taxi drivers, public services, the armed police, traffic police, security guards, media reporters, express delivery industry such as personnel, because of daily contact personnel is more, there is risk of infection, its place unit should be configured disposable surgical masks or medical surgical masks or KN95  or higher particulate respirators.