Generally speaking, disposable medical masks are completely sufficient for our daily use as long as we do not come into direct contact with confirmed patients.
The following is an explanation
The structure and protective principle of disposable medical surgical masks
Outer layer: water-repellent layer, mostly polyester needle felt, polyester itself Water-repellent, made of needle-punched non-woven fabric, which can block large droplets
Middle: filter and electrostatic layer, the main material is polypropylene, a material that easily generates static electricity, try to stay away from it when buying clothes, but as The mask can absorb droplets
Inner layer: hot-rolled non-woven fabric with good moisture absorption and breathability, which can keep the mouth moist and improve comfort
Comparison
For ordinary disposable medical masks, the outer water-repellent and filtering layers are reduced by one level.
Medical protective masks have better water repellency
▲According to Academician Zhong Nanshan, general masks (here refers to medical surgical masks) can block most viruses from entering the respiratory tract
Regardless of medical masks, industrial dust masks, or gas masks, the testing standards do not include anti-virus. Because the virus itself cannot exist independently, but exists in droplet and aerosol state droplet nuclei. Masks filter droplets and droplet nuclei to achieve anti-virus effects.
Diameter >10 microns: Even the worst skim gauze mask can filter more than 80% of these large droplets.
Diameter <0.1 micron: This extremely small droplet core is adsorbed through electrostatic effect and is easily filtered. The filter layer of masks is mostly made of electrostatic adsorption materials (such as polypropylene), and washing with water will reduce the adsorption effect.
Diameter ≈ 0.3 micron: This type is the most difficult to filter, so the mask testing standards all use 0.3 micron sodium chloride. As long as it passes the test, filtering other particles is not a problem.
The diameter of 82 droplet nuclei ranges from 0.74 to 2.12 microns.
Disposable medical surgical masks have a droplet filtering effect of more than 80%.
Even ordinary disposable medical masks have a filtration effect of more than 70%.
If a disposable surgical mask is used to filter particulate matter, the filtration effect is about 30. This data comes from the Internet and is not a scientific test result. It can be used as a reference indicator.
KN95 level dust mask can filter more than 95% of sodium chloride particles; KN90 can filter more than 90% of sodium chloride particles. Use dust masks instead of disposable medical surgical masks for better results.
Activated carbon masks, skim gauze masks, polyurethane sponge masks, and ordinary disposable masks are less effective. These masks have neither a medical-grade waterproof layer nor an intermediate electrostatic adsorption filter layer, and can only filter large droplets.
If you only have these types, it is recommended to wear 2 layers, throw away the outer layer after use, and keep the inner layer for use outside.