HEPA (High Efficiency Particulate Air) and ULPA (Ultra Low Penetration Air) filters are certified according to the EN 1822-1 April 2019 standard, which defines the classification of absolute air filters into three groups: E (EPA - high efficiency), H (HEPA - very high efficiency) and U (ULPA - very low penetration). These filters are categorised according to their efficiency in retaining the finest and most difficult to capture particles (Most Penetrating Particle Size, MMPS).
The HEPA and ULPA categories are both very effective in capturing pollutants, and in particular fine particles (dust, pollen), from indoor air. Their main difference lies in the size of the particles that these filters will effectively trap between their fibres:
The HEPA 13 (or H13) filter is effective against 99.95% of fine particles larger than or equal to 0.3 microns,For the HEPA 14 (or H14) filter, this efficiency rises to 99.995% for the same size of fine particles,Finally, the ULPA 15 (or U15) filter retains at least 99.9995% of particles in the ambient air with a diameter larger than or equal to 0.3 microns.
Classification of absolute air filters*MMPS : Most Penetrating Particle Size