According to the technical specifications for daily protective masks,The concentration of PM2.5 inhaled will be reduced to less than 75 μ g / m3 after wearing the masks of various protection levels, that is to say, the air quality in the inhaled body will be good or above after filtration,It is the qualified daily protective mask.
It is well known that wearing protective masks is mainly used to prevent fine particles in the air. According to GB 3095 & mdash; 2012 ambient air quality standard, quasi fine particles refer to particles with equivalent aerodynamic diameter of less than or equal to 2.5 microns in the ambient air, also known as fine particles. Relevant research literature shows that the particle size of bacteria is (0.5-5) μ m, the particle size of sneezing and coughing droplets is (2.5-28) μ m, and the particle size of small pollen is (4-8) μ M. The protection object of this standard can not only effectively protect fine particles (PM2.5), but also can be used for the protection of ordinary bacteria, droplets and pollen, and can also protect large particles.
Different from the previous standard of respirator, this standard specially sets the index of protective effect, which comprehensively considers the filtering efficiency and the tightness of the combination of respirator and human face. Guide the public to choose suitable masks according to different pollution conditions when the air environment is polluted.According to the protection performance, the protection effect grade of the respirator is divided into four grades: Grade A, grade B, grade C and grade D; the corresponding protection effect of each grade is not less than 90%, 85%, 75% and 65% respectively; the applicable air quality index categories of each grade are: serious pollution (PM2.5 concentration reaches 500 μ g / m3), serious and below pollution (PM2.5 concentration ≤ 350 μ g / m3), serious and below pollution Pollution (i.e. PM2.5 concentration ≤ 250 μ g / m3), moderate and below (i.e. PM2.5 concentration ≤ 150 μ g / m3)