HEPA uses:

HEPA is an internationally recognized and best high-efficiency filter material. HEPA was originally applied to nuclear energy research protection. It is now widely used in precision laboratories, pharmaceutical production, atomic research, and surgical operations that require high cleanliness. HEPA is made up of very small organic fibers. It has a strong ability to capture particles, a small aperture, a large adsorption capacity, high purification efficiency, and water absorption. The particle purification rate for 0.3 microns is 99.97 %. That is, only 3 particles per 10,000 particles can penetrate the HEPA filter membrane. Therefore, the effect of filtering particles is very obvious! If it is used to filter cigarettes, the filtration effect can reach almost 100, because the particle size in cigarettes is between 0.5 and 2 microns and can not pass through the HEPA filter membrane. The main role is to filter air particles on the side of the air.