Filter classes

Transition from EN779 to ISO 16890

With the introduction of DIN EN ISO 16890, the previous DIN EN 779 standard was replaced. DIN EN ISO 16890 was published in December 2016, and there was a transition period during which both standards applied side by side. This transition period ended in 2018, after DIN EN 779 was officially withdrawn.

For manufacturers, this meant that they had to test and label their products in accordance with the new standard. For users and planners, the changeover meant that they had to familiarise themselves with the new filter classes and the associated requirements. It was important that all parties involved, from manufacturers to installers to end users, were aware of the changes and their effects.

It should also be noted that although DIN EN 779 is no longer valid, filters that have already been installed and have been marked in accordance with this standard can continue to be used until they have to be replaced. However, when retrofitting or replacing old filters, the new standard should be considered.

Classification of air filters in accordance with ISO 16890

Air filters are essential components of ventilation and air conditioning systems, which are used to remove particles and contaminants from the air. They not only protect people from harmful particles and microorganisms, but also machines and equipment from contamination and wear and tear.

Air filters can be classified in various ways, but one of the most common methods is ISO 16890, which classifies filter efficiency in terms of particle size. Filters are divided into three main groups: ePM1, ePM2.5 and ePM10. This classification refers to the size of particles that the filter can effectively remove/retain.

ePM1: This class of filters is able to remove ultrafine particles with a diameter of less than 1 micron (µm). These particles include many types of bacteria, smoke, and some viruses. A high EPM1 value indicates that the filter is particularly effective at removing these ultrafine particles.

ePM2.5: These filters effectively remove particles with a diameter of less than 2.5 µm. This includes many types of fine dust, pollen, and mold spores. A high EPM2.5 value indicates that the filter is particularly effective at removing these particle sizes.

ePM10: These filters are designed to remove larger particles with a diameter of less than 10 µm. These include, for example, coarse dust, pollen and many types of insect spores. A high EPM10 value indicates that the filter is particularly effective at removing these larger particles.

In addition to the EPM classes, which are defined in the ISO 16890 standard for finer particles, there is also the “ISO Coarse-” category. This category refers to filters that do not meet the criteria for EPM classes but still have some efficiency in removing coarser particles.

ISO Coarse-filters are primarily designed to remove larger particles from the air. They are less efficient at removing finer particles captured by EPM classes. These filters are often used as pre-filters in ventilation and air conditioning systems. They are used to remove larger particles such as insects, leaves, larger dust particles and other gross contaminants before the air is passed through finer filters (e.g. ePM1, ePM2.5 or ePM10). A primary purpose of ISO Coarse-filters is to extend the life of downstream, finer filters. By removing the coarser particles, they prevent these finer filters from clogging or being damaged quickly.

The efficiency of ISO Coarose filters is usually reported as a percentage of particles removed, often specifying the exact particle size for which they were tested.


The classification of air filters in accordance with ISO 16890 provides a clear and understandable method for determining the efficiency of filters in terms of particle size. It is important to choose the right filter class based on the specific requirements of each application in order to ensure both the health of people and the longevity of the machinery and equipment.

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