At present, why not do something related to the epidemic! Wearing a mask is very important for protecting the new coronavirus! If you can't buy a mask, try it yourself!
The masks that can play a role in virus protection include medical surgical masks and N95 masks. Important technical indicators that medical surgical masks must achieve include filtration efficiency, bacterial filtration efficiency (BFE) and respiratory resistance:
Filtration efficiency: Under the condition of air flow (30 ± 2) L / min, the filtration efficiency of aerodynamic median diameter (0.24 ± 0.06) μm sodium chloride aerosol is not less than 30%; bacterial filtration efficiency: within the regulations Under the conditions, the filtration efficiency of the Staphylococcus aureus aerosol with an average particle diameter of (3 ± 0.3) μm is not less than 95%; respiratory resistance: under filtration efficiency flow conditions, the inhalation resistance does not exceed 49Pa, the exhalation resistance No more than 29.4Pa.
Among them, the second standard for ensuring the filtration effect of bacteria is the second. The filtration efficiency of Staphylococcus aureus bacterial aerosol (3 micron level) is not less than 95%. The new coronavirus is an enveloped, non-segmented single-stranded positive-strand RNA virus. The particles are round or oval, and the diameter is about 60-140nm (0.06 ~ 0.14 microns). Although medical surgical masks have only 30% filtration efficiency for 0.3-micron particles, because viruses, bacteria and other pathogens cannot be isolated in the air, they must be attached to dust, droplets and other micelles, so they can also provide effective virus protection.
The grades of medical masks are as follows: Level 1 is the same as N95, Level 2 is the same as N99, and Level 3 is the same as N100. (Indicating that the filtration efficiency of aerosols with a diameter of 3 microns in air is not less than 95%, 99% and 99.97%, respectively.
Therefore, although the N95 mask is not a medical mask, its particle filtration efficiency meets the standard of not less than 95%, and can better fit the human face, so it can also play a good role in virus prevention.
The main material that brings virus filtering to these two masks is the very fine and static inner filter cloth-meltblown nonwoven fabric.
The main material of melt-blown non-woven fabric is polypropylene, which is a kind of ultra-fine electrostatic fiber cloth that can capture dust. When the droplets containing pneumonia virus are close to the melt-blown non-woven fabric, they will be electrostatically adsorbed on the surface of the non-woven fabric and cannot penetrate. This is how this material isolates germs. After the dust is caught by the ultra-fine electrostatic fibers, it is extremely difficult to separate due to cleaning, and the washing will also destroy the electrostatic suction ability of the static electricity. Therefore, this mask can only be used once. Suitable for flat masks meltblown filtration levels are: ordinary grade, BFE95 (filter efficiency 95%), BFE99 (filter efficiency 99%), VFE95 (filter efficiency 99%), PFE95 (filter efficiency 99%), KN90 (filter efficiency 90%) ).
Medical surgical masks are generally made of three layers of non-woven fabrics. The material is spunbond nonwoven fabric + meltblown nonwoven fabric + spunbond nonwoven fabric. You can also use a layer of staple fiber to improve skin feel, that is, ES hot-rolled nonwoven fabric + meltblown nonwoven fabric + spunbond nonwoven fabric. The outer layer of the mask has anti-spray design, the middle layer is filtered, and the memory absorbs moisture. Meltblown cloth is generally selected to weigh 20 grams.
The N95 cup mask is composed of needle-punched cotton, melt-blown cloth, and non-woven fabric. The melt-blown cloth usually uses 40 grams or more, and the thickness of the needle-punched cotton, so the appearance looks more flat The mask is thicker, and its protective effect can reach at least 95%.
1. The most important N95 meltblown nonwoven fabric is purchased on Amazon;
2. It is recommended to use acupuncture cotton for the outer layer material, which can prevent the finished mask from being too dull and unfavorable for breathing. Needle-punched cotton is also called polyester needle felt. This product has the advantages of high porosity, good air permeability, high dust collection efficiency and long service life, which are unique to ordinary felt filter cloth. Taobao can be purchased;
3. The inner layer material is recommended to use hot-rolled non-woven fabric or medical gauze, which can improve comfort;
4. If further improvement is needed. It is possible to purchase a plastic nasal splint to stick to the inner layer of the mask. When using it, soak it in hot water at 70 or 80 degrees, take it out and fit it on the nose after softening;
5. Ear straps, ordinary cloth straps are enough;
6. Use super glue or needle thread to glue or sew the three layers of mask material along the edges and fix the ear straps on both sides of the mask.
The most important thing during a crisis is to stay calm and not panic. Do normal protection, pay attention to personal hygiene, and improve your resistance. We have serious and professional medical staff who are not afraid of sacrificing, and we can certainly control the virus.
