What is MERV Rating?
MERV Rating provides a description of what your air filter captures by particles. Many in the air filtration industry have also developed their own measuring methods of what their air filter captures by particles. From 2019 there was a new and international standard ISO 16890 which is now common to all sellers of air filters. This standard provides accurate descriptions of what your filter captures by particles.

Here is an overview:


Instead of MERV 8,10,11 etc we now have Iso classes ePM1, ePM2.5 and ePM Corse. This gives a much better description of what your filter actually captures. PM stands for "particulate matter", and the number after "PM" indicates the size of the particles measured in μm.

PM1 is all particles up to and including 1 µm (everything from viruses and nanoparticles to car exhaust).

PM2.5 are particles larger than 1 μm and up to and including 2.5 μm (for example, bacteria, fungal spores and pollen).

PM10 is particles larger than 2.5 µm up to and including 10 µm (for example, litter sand and asphalt wear particles).


Here are 3 examples 

Iso ePM  1  50%  captures a mimimum of 50% from 0 to 1 µm size particles. 

Iso ePM 2,5 65% captures a mimimum of 65% from the 1 to 2,5 µm size particles.

Iso ePM Coarse 75% captures a mimimum of 75% from the 2,5 to 10 µm size particles.


Do not be satisfied with filters that are not rated with ISO rating. Both MERV and all other standards are now on the way out. A proper premium filter should have an Iso standar and a classification of what it captures.

All filters from Norwegian Airfilters are acording ti ISO 16890.  Most filters are classified as ISO ePM 2,5 65% . But we also offer  ISO ePM 1 55%

Choose an air filter that gives you healthy air – choose Norwegian Airfilters.