Description
The United States Department of Energy defines HEPA as High-efficiency particulate air (filter). These filters are specifically designed to remove airborne “most penetrating particles” (MPPs) with a diameter of 0.1-0.3 µm. HEPA filters are classified into efficiency classes, which range from H10 to H14.
Particles smaller than 0.1 µm need to be clustered in order to be filtered. In contrast, the filter directly holds up particles larger than 0.4 µm.
HEPA Filters used in air cleaner are categorized according to the retention rate.
Difference of HEPA13 and HEPA14 are as follow:
| HEPA class | Retention (total) |
| HEPA 13 | >99.95% |
| HEPA 14 | >99.995% |
