What kind of masks are commonly used ?

Masks can be classified into two categories: one is according to filter material and filter effect; the other is according to use environment and function.  Masks are developed to prevent dust and breath pollution .  There are mainly the following categories:  

一.  According to filter material and filter effect classification 

N series: no time limit for protection against non-oily suspended particles (the N95 mask we often see is this classification)

R series: protection time of non-oil suspended particles and sweat oil suspended particles is 8 hours

P series: protection of non-oil suspended particles and sweat oil suspended particles without time limit. This is the mask classification according to the filter material. These three categories are divided into three levels according to their filtration effect: 95%, 99% and 99.97%(namely, 95,99,100 for short), so there are altogether 9 categories of filter materials.This is also the origin of the N95 mask that we often hear about, which filters 95% of non-oily suspended particles. 

二. Masks are classified according to their environment and function 

The classification of masks according to the use environment and function is not so strict, but the common classification of masks, mainly include: 1. Cotton mask: suitable for wearing in winter, mainly for anti-freezing; 2.2. Medical non-woven mask: it is the blue mask, which is mostly used in hospitals, and is also widely used in ordinary families, but it is mainly used to prevent germs;3, activated carbon mask: this mask is to add activated carbon in the mask interlayer, can effectively protect against bacteria and dust;4, dust mask: generally used in the dust environment, this mask is usually tightly sealed, with a breathing valve, can be very good dust;5, N95 mask: N95 mask is the mask mentioned above. It is relatively reliable to prevent haze. The main component of haze, PM2.5, is non-oily suspended particles.  

   KN masks have not been tested for synthetic blood penetration, surface moisture resistance, and therefore, they can be used for short periods of time to block the virus, but should not be used for contact with patients who may have spatter or prolonged contact.

The technical specification for daily protective masks is the standard for civil masks, which is proposed by China National Textile And Textile Federation and is under the focus of National Technical Committee of Standardization on Textiles (SAC/TC209).