recuperator filter classes The old and new filter markings still exist in most stores that sell filters for recuperators. When ordering filters for our recuperator, we usually choose according to the old standard common filter class, such as F7, M5, G2, etc. depending on which recuperator we buy filter sets or filters. It is difficult to escape from habits, but it is necessary, because in 2018 after the new standard entered into force, the filter testing requirements and filter classes were changed to ePM1, ePM2.5, ePM10, Coarse.

Comparison of EN 779 and ISO 16890

According to the published Eurovent association document , the filter classes described in both standards cannot be directly compared, because the testing methodology has changed, which in the new standard checks the filter's ability to retain solid particles of 0.3µm - 10µm size. Meanwhile, the old standard tests the ability to hold solid particles of one size ie 0.4µm, which does not reflect the environment around us at all. Of course, in order to facilitate adaptation to new changes for manufacturers, sellers, and customers, the association has provided an indicative comparison that can be used as a guide:

EN 779

ISO 16890 - Measured average efficiency

Filter class

ePM 1

ePM 2.5

ePM 10


5% - 35%

10% - 45%

40% - 70%


10% - 40%

20% - 50%

60% - 80%


40% - 65%

65% - 75%

80% - 90%


65% - 90%

75% - 95%

90% - 100%


80% - 90%

85% - 95%

90% - 100%

*ePM 1 (e-efficiency), PM - Particulate matter (solid particles), 1 - all solid particles smaller than 1µm), expressed as a % filter efficiency for filtering solid particles.

For example, sells filters for Komfovent and Salda recuperators, corresponding to ePM 10 55% and ePM 1 70% efficiency. We can be happy that our ePM 1 filters correspond even to the F8 class according to the old standard.

Simplified marking of filter classes on the page

A simplified notation of filter classes helps to understand the use of filters in everyday life. On the page, we have divided the filter classes into two categories: Standard and Effective.



ePM 10 55% + ePM 10 55%

ePM 1 70%+ ePM 10 55%

Moderate protection against solid particles 10 μm and smaller.

Effective protection against 0.3-10 μm solid particles.

*ePM 1 (e-efficiency), PM - Particulate matter (solid particles), 1 - all solid particles smaller than 1µm), expressed as a % filter efficiency for filtering solid particles.

In a language we all understand, this is what our old standard designation would look like: Standard M5+M5 and Effective F7+M5.

Particle sizes and their effects on health

When creating the new ISO 16890 standard, a lot of attention is paid to human health. A dozen studies have investigated the correlation between indoor air quality and human health. Studies have shown that solid particles are particularly harmful to human health compared to other, similar indoor pollution. Solid particles include sulfates, nitrates, ammonia, sodium chloride, black carbon, mineral dust, combustion particles, various liquid droplets. These particles, according to studies, can cause allergies, asthma, lung cancer, cardiovascular diseases, and dementia. The tables below will help you understand the size and penetration of solid particles into the human body:

ePM 10

ePM 2.5

ePM 1

Particles 10 μm and smaller can reach the respiratory tract and be manifested by coughing or sneezing.

Particles of 2.5 μm penetrate deep into the lungs and cause reduced lung function, and can also cause skin and eye problems.

Particles 1 μm and smaller are small enough to enter the bloodstream and cause cancer or heart disease.

Particle sizes:

The name of a natural solid particle

Size, μm

The name of the artificial solid

Size, μm

Mold spores




Pollen, fertilizers


Tobacco smoke




Fines and other combustion products


Dust mite allergens


Car emissions


Human hair


Cement dust


L. Rytas report on solid particles, their impact on health: