HEPA filters according to EN1822-1: 2009 are divided into three groups:
EPA – these are effective air filters, they are marked with the letter E (E10-E12),
HEPA – a highly effective air filter, marked with the letter H (H11-H14),
ULPA – literally translated air filters with very low penetration, i.e. those with the highest efficiency of all HEPA filters (U15-U17).