Comparative guidelines for EN 779:2012 and ISO 16890:2017. Under ISO 16890:2017, filters are divided into 4 classes: ISO Coarse, ISO ePM10, ISO ePM2,5, and ISO ePM1. Under EN 779:2012, however, filters were divided into 3 efficiency classes: for coarse (C), Medium (M) or Fine (F) particles.
The international standard ISO 16890:2017 replaced both EN 779:2012 in Europe and ASHRAE 52.2 in America in June 2018.
The US legislation classified filters according to the MERV rating scale, based on the efficiency of the filter in removing small and large airborne particles. There are 4 MERV classes: MERV 1–4 (to remove only the largest particles, MERV 5–8, MERV 9–12, and MERV 13+ (to remove the smallest particles).