Dust masks with high effective filtration rate, high tightness and comfort are also effective, such as N90, N95, N98 and other medical masks, and the best ones on the market at present are masks made of advanced medical silicone materials. Dust in the natural environment, according to the size of dust particles, can be divided into visible dust, microscopic dust, ultra-fine dust. Ordinary masks for visible dust has a certain blocking effect, but on the microscopic dust and ultra-fine dust, can not play an effective blocking effect, and dust special masks, such as medical N90, N95, N98 and other models, can effectively filter rate of tiny particles, blocking the vast majority of dust. In addition, the mask’s closeness and comfort is also very important, the mask should fit the face, tightly cover the mouth and nose, and breathable, does not affect normal breathing. It is recommended to buy from regular channels and seek medical advice if you feel unwell.