HEPA (/ˈhɛpə/, high-efficiency particulate air) filter,[1] also known as high-efficiency particulate absorbing filter[citation needed] and high-efficiency particulate arrestance filter,[2] is an efficiency standard of air filters.[3]
Filters meeting the HEPA standard must satisfy certain levels of efficiency. Common standards require that a HEPA air filter must remove—from the air that passes through—at least 99.95% (ISO, European Standard)[4][5] or 99.97% (ASME, U.S. DOE)[6][7] of particles whose diameter is equal to 0.3 μm, with the filtration efficiency increasing for particle diameters both less than and greater than 0.3 μm.
你自己睇幅圖諗下先啦
我懷疑你連HEPA 係乜都有誤解