Materials and Construction The main body consists of non-woven fabric, melt-blown fabric or filter material. The major material of the mask belt is generally non-woven fabric ( banding type ) or elastic ring ( dangling ear type). Melt blown cloth or filter material may provide better filtering functionality. The outer non-woven fabric material ( usually blue ) has water repellency and contains a " lotus leaf effect"; the inner white coating is water-absorbent. The skin is much better [2] .
Main technical prerequisites
Compared with disposable medical masks, the main technical requirements of these masks are appearance, construction and size, nose clip, hide belt, filtration efficiency, stress difference, microbial indicators, residual ethylene oxide, skin irritation, and mobile along with toxicity, delayed hypersensitivity and other items, it is particularly necessary to investigate the penetration of artificial blood. 2 mL of artificial blood is 16%. Following the pressure of 0 kPa is sprayed on the exterior of the mask, there should not be a penetration on the inside of the mask. In addition, investigations on fire retardant properties have been added. The mask material needs to be produced of non-flammable substances, and the mask should not burn over 5 after leaving the flame . Microbiological signs are equivalent to disposable medical masks [2].
medical protective masks
Materials and Construction
The inner layer is made from non-woven fabric.
It has a certain level of comfort; the middle layer is constructed of ultra-fine polypropylene fiber melt-blown material, which can provide better filtering performance; the outer layer is a layer of non-woven cloth and ultra-thin polypropylene melt-blown material, which has a specific waterproof performance. Medical protective masks cannot be equipped with breathing valves [3].
Main technical prerequisites
On the basis of medical surgical masks, it's more requirements in terms of airflow resistance, surface moisture resistance, and adhesion. Gas flow rate of 85 L / min at the instance, a mask for the filter efficiency of the non fatty particles must meet the next requirements: 1 stage particle filtration efficiency ( Particulate Filtration Efficiency, the PFE) ≥ 95% ( i.e., N95); 2 phase the PFE ≥ 99 percent; Grade 3 , PFE ≥ 99. 97%. When the gas flow speed is 85 L/min, the inhalation resistance of the mask doesn't exceed 343 . two Pa . The outer surface of the mask needs to be not less than spray evaluation GB / T 4745 - 1997 in three predetermined levels. Among the microbiological indicators, the entire number of bacterial colonies of this mask should be no longer than 200 cfu/g , E. coli, Pseudomonas aeruginosa, Staphylococcus aureus, hemolytic streptococcus, etc. shouldn't be detected, and the total number of bacterial colonies should not exceed 100 cfu/g; Masks marked as sterile or sterile about the packing ought to be sterile. The mask layout should offer good tightness, and also the total fit variable of the mask should not be less than 100 [3].
Non -medical protective masks
Materials and Construction
Such masks incorporate daily protection sprays and particulate respirator, the structure is generally 3 layers or 3 or more layers, inner and outer layers is a nonwoven fabric, generally without the outer liquid barrier function. The filter coating can be divided into coarse filter PET filter coating, high efficiency PET filter coating, high efficiency melt blown filter coating, electrostatic filter cotton, etc., and also activated carbon layer can also be inserted in line with the function [4] . Non-medical protective masks could be outfitted with breathing valves. The breathing valve is a one-way valve that simply lets the exhaled gas to exit the mask through it, and prevents the pressurized gas from passing to the mask. When exhaling, the breathing valve opens, and the exhalation is directly out of the body, reducing the exhalation immunity and lowering the moisture from the mask, thereby reducing the wearer's breathing problem, maintaining the face sterile, and prolonging the wearing time. The main technical index of the breathing valve would be that the cover fastness, which shouldn't be slipped, broken or deformed.
Main technical prerequisites
In 2018, that the National Health Commission's Infection Prevention and Control Bureau"Based on PM2. 5, resulted in heavy pollution weather wellbeing education center message of pollutants,"indicated favored marked with heavy pollution weather GB / T 32610 - 2016 standard masks. Masks that meet the standards have good protective performance and can effectively filter or block PM2 . 5 [5 ] . Protective effect daily protection respirators descending into A class, B class, C class, D grade . 4 stages, respectively the protective effect was ≥90%, ≥85%, ≥75 percent, ≧ 65%, More Information are to be implemented The air quality indicator is intense contamination, intense pollution and below, severe pollution and below, moderate pollution and below. 
