What aspects should users start from when purchasing disposable medical masks? Now the natural environment is getting worse and worse. When going out, people will wear disposable masks, but what aspects should people buy disposable medical masks? Dust control efficiency. The dust-proof efficiency of the mask is based on its blocking efficiency to fine dust, especially the respirable dust below 2.5 μ M. Because this particle size can enter the alveoli directly, it has a great impact on human health. The dust-proof principle of gauze mask is mechanical filtration, that is, when the dust impacts the gauze, it will block some large particles of dust in the sand cloth through the multi-layer barrier. Some fine dust, especially those smaller than 2.5 microns, passes through the mesh and enters the respiratory system. The dust mask is composed of filter material, activated carbon fiber pad or non-woven fabric, and the respirable dust less than 2.5 μ m passes through the dust mask. First, let's learn about the face mask. No matter it's Bai disposable mask or other masks, it has positive and negative sides. For disposable mask Dao, the dark color is the front, and the front is outward. Look at the picture below, which is circled in red, with a metal bar in the nose clip. 2. The reverse side of disposable masks is lighter and the opposite side is inward, that is to say, the light color side is close to our face. In addition, it should be noted that one end of the metal strip is the top of the mask, so it should not be reversed. 3 points clearly the front, back, top and bottom of the mask, it is not far from the correct way to wear the mask. After washing your hands, make sure that the light colored side of the mask is facing inward (reverse side), and one end of the metal strip is facing up (top). Hang the rope on both ends of the mask on your ears. Do you think the mask is on and finished? The answer is definitely no, look at the more important step, you need to press the metal strips on both sides of the bridge of the nose with both hands to make the upper end of the mask close to the bridge of the nose. Then stretch the mask downward so that the mask does not leave wrinkles and better cover the nose and mouth. OK, it's done.