EN 779 / ISO 16890

Old standard (EN 779)	New standard (ISO 16890)	Use & Explanation
G1 - G4	ISO Coarse ≥ 50 %	For coarse dust, Pollen, hair - more suitable as a pre-filter
M5	ISO ePM10 50-65 %	Filters min. 50 % of particles ≤ 10 µm (e.g. Pollen, coarse fine dust)
M6	ISO ePM2,5 50-65 %	Filters at least 50 % of particles ≤ 2.5 µm (e.g. fine dust, Mould spores)
F7	ISO ePM1 50-65 %	Filters min. 50 % of particles ≤ 1 µm (e.g. Fine dust, many bacteria)
F8	ISO ePM1 70-80 %	Higher protection against fine dust and bacteria
F9	ISO ePM1 ≥ 80 %	Very high protection, also for sensitive areas (hospital, Clean rooms)

EN 779 was the old standard for air filters in ventilation and air conditioning systems.
Filters were created in G classes (G1-G4), M5 classes (M5-M6) and F classes (F7-F9).
The assessment was based primarily on ability, Retain particles of a certain size (usually 0.4 µm).
Disadvantage: It did not reflect the real particle sizes in the air, which are important for health (e. g. E.g. particulate matter PM10, PM2.5, PM1).

This standard has superseded EN 779.
It now rates filters according to their effectiveness against fine dust, which is also known from environmental reports:
- PM10=coarse dust, Pollen, Mould spores
- PM2,5=fine dust, Bacteria
- PM1=ultrafine dust, that gets deep into the lungs
A filter is used, for example, as . E.g. as ISO ePM1 70 % → means: The filter removes 70 % of the particles in the size ≤1 µm.

Advantage: End customers can immediately recognise which filter is best for health protection and air quality.