HEPA (High efficiency particulate air filter), meaning high-efficiency air filter, meaning HEPA filter, with an efficiency of 99.998% for 0.1 micron and 0.3 micron. HEPA net is characterized by air passing, but small Particles cannot pass. It has a particle removal efficiency of 99.7% or more for diameters of 0.3 microns (1/200 of hair diameter) and is the most effective filter media for smoke, dust, and bacteria. (The smoke particles produced by smoking have a diameter of 0.5 μm.) It is an internationally recognized high-efficiency filter material. Has been widely used in operating rooms, animal laboratories, crystal experiments and aviation and other high clean places.