Air filtration is a big category, It can be divided into filtering PM2.5 and filtering peculiar smell. Among them, filtering PM2.5 can be divided into high-efficiency junior high school. The primary effect is to filter some pollen, impurities, hair, etc. with larger particles. Some are to filter finer particles, some are PM2.5, and some need to filter finer particles. And filtering the peculiar smell in the air is also a big category, such as filtering the smell of smoke, the smell of oil in the kitchen, the formaldehyde in the new house, the new car, the stupid smell, and the smell of ozone produced by the disinfection machine. There are also filters on the market that need to remove the smell of the elderly from the elderly in nursing homes. Therefore, we must first figure out which part of the air to filter, and then decide what material to use. Generally speaking, to filter particulate matter in the air, the materials used are some fine meshes, some non-woven fabrics, and some sponges. , which can play a role in filtering particles. If you want to filter finer particles, you have to use HEPA, or melt spray cloth, which is equivalent to the material of the mask, and some medical schools, and the actual room of the Academy of Sciences, require a dust-free sterile workshop, and the melt used The filter level of the spray cloth is even higher. If you need to filter out the odor in the air, you need to use activated carbon, a carrier, and a chemical formula, and these formulas are often the survival secret of every company.