It is made of very fine organic fibers intertwined, and has a strong particle trapping ability, small pore size, large adsorption capacity, high purification efficiency, and water absorption. The particle purification rate for a 0.3 micron particle is 99.97%. In other words, only 3 particles per 10,000 particles can penetrate the HEPA filter membrane. The effect of HEPA filtration particulate matter is very obvious. If it is used to filter cigarettes, the filtering effect can reach almost 100%, because the particle size in the cigarette is between 0.5-2 micron and cannot pass the HEPA filter membrane.