A HEPA filter is a specific type of high quality air filter that meets the HEPA filter standard, which is to remove at least 99.97% of particles from the air down to at least 0.3 microns in size. HEPA filters are a common component found in air purifiers which filter the air in order to clean it – there are other types of air purifier such as carbon filter, ionizers and even non-filter purifiers.
A HEPA filter is a specific type of high quality air filter that meets the HEPA filter standard, which is to remove at least 99.97% of particles from the air down to at least 0.3 microns in size. HEPA filters are a common component found in air purifiers which filter the air in order to clean it – there are other types of air purifier such as carbon filter, ionizers and even non-filter purifiers.
HEPA filters are usually manufactured by pleating microfiber glass or other fibrous media made with multiple layers of randomly arranged fibers, with diameters ranging from 2 to 500 nm.4 As air flows through the filter and in between the fibers, airborne particles—such as respiratory and aerosol droplets—will be trapped by 1 of 3 mechanisms: impaction, interception, and diffusion
To qualify as HEPA grade, filters must remove at least 99.97% of all particles that are 0.15 to 0.2 µm, for which HEPA filters are least effective. Thus, HEPA filters have at least 99.97% efficiency for removing all particles, with even higher efficiencies for particles both larger and smaller than 0.15 µm
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