Publication of ISO 16890-1 and Air Filters for General Ventilation

10 July 2018

ECE UK Ltd have spent valuable time reading and understanding the new ISO standard for the testing and classification of air filters used in general ventilation systems.

This document summarises ISO16890 and the implications it has on air handling units and filtration for buildings.

This new standard has global applicability and will be applied in all our markets. After a period of time ISO16890 will replace EN779:2012 and the European norm will be removed. The removal is most likely to be during 2018.

The effects of particulate matter (PM) on human health have been extensively studied in the past decades. The results are that fine dust can be a serious health hazard, contributing to or even causing respiratory and cardiovascular diseases.

Air filters for general ventilation are widely used in heating, ventilation and air-conditioning applications of buildings. In this application, air filters significantly influence the indoor air quality and, hence, the health of people, by reducing the concentration of particulate matter.

To enable design engineers and maintenance personnel to choose the correct filter types, there is an interest from international trade and manufacturing for a well-defined, common method of testing and classifying air filters according to their particle efficiencies, especially with respect to the removal of particulate matter. With this new ISO 16890 series, a completely new approach for a classification system is adopted, which gives better and more meaningful results compared to the existing standards. 

Different classes of particulate matter can be defined according to the particle size range. The filters are classified in to three fine-particle filter groups: ePM10, ePM2,5 and ePM1 as well as one coarse-particle filter group "ISO Coarse".  The most important ones are ePM10, ePM2,5 and ePM1. The filter group ePM1 is the group with the highest filter capacity.

The U.S. Environmental Protection Agency (EPA), the World Health Organization (WHO) and the European Union define PM10 as particulate matter which passes through a size-selective inlet with a 50 % efficiency cut-off at 10 µm aerodynamic diameter. PM2,5 and PM1 are similarly defined.

In Europe, the reference method for the sampling and measurement of PM10 is described in EN 12341. The measurement principle is based on the collection on a filter of the PM10 fraction of ambient particulate matter and the gravimetric mass determination (see EU Council Directive 1999/30/EC of 22 April 1999).

Particulate matter in the context of the ISO 16890 series describes a size fraction of the natural aerosol (liquid and solid particles) suspended in ambient air. The symbol ePMx describes the efficiency of an air cleaning device to particles with an optical diameter between 0,3 µm and x µm.

Please find below a brief explanation into the new classifications.

  • ePMCoarse - Less than 50% efficiency in particles 10 micron or larger e.g. dust, sand, leaves, hair and other large organic particles.
  • ePM10 - Minimum 50% efficiency on particles 0.3 micron to 10 micron in size e.g. particles caused by crushing and grinding such as dust stirred up by vehicles on roads.
  • ePM2.5 - Minimum 50% efficiency on particles 0.3 micron to 2.5 micron in size e.g. particles produced from combustion such as motor vehicles, power plants and industrial processes.
  • ePM1 - Minimum 50% efficiency in particles 0.3 micron to 1 micron in size e.g. particles that enter the body through the respiratory system such as fine duct, bacteria and smaller spores.


How ISO16890 compares to EN779:2012

  EN779:2012 ISO16890
Filter test method Efficiency measurement made using 0,4µm particles Efficiency measurements made using 0, 3- 10µm particles.
Classifications relate to result for PM1, PM2.5 & PM10
Discharging method Discharge only filter media, using IPA soak.
A tough discharging method.
Discharge entire filter using IPA vapour.
A tough discharging method
Filter loading method Dust loading with ASHRAE dust.
Coarse dust.
Dust loading with ISO fine dust.
Fine dust (more like real-world).
Classification system 9 Classes 49 Classes
In 4 different groups


Benefits of ISO16890

For specifiers, purchasers and users of air filters
  • The standard recognises that air filters positively influence indoor air quality and human health.
  • The test method and filter classification system are better aligned with real-world pollution.
  • The global applicability will eliminate confusion that occurred when attempts were made to compare results of EN779 and ASHRAE 52.2 tests.


For the filter industry
  • It will be easier to compare products. This will drive innovation and customer value. Very poor performing products may be eliminated.
  • Easier to explain product value in terms of function and customer application.
  • This standard will remove an obstacle to global trade.


ISO16890: Overview of Classification System

Group Designation Requirement Class reporting value
  ePM1, min ePM2.5, min ePM10  
ISO Coarse - - <50% Initial gravimetric arrestance
ISO ePM10 - - >/=50% ePM10
ISO ePM2.5 - >/=50% - ePM2.5
ISO ePM1 >/=50% - - ePM11


ISO16890: Classification Table

PM1 Classification PM2.5 Classification PM10 Classification Coarse
ePM1 95% ePM2.5 95% ePM10 95% Arrestance reported in 5%
ePM1 90% ePM2.5 90% ePM10 90%  
ePM1 85% ePM2.5 85% ePM10 85%  
ePM1 80% ePM2.5 80% ePM10 80%  
ePM1 75% ePM2.5 75% ePM10 75%  
ePM1 70% ePM2.5 70% ePM10 70%  
ePM1 65% ePM2.5 65% ePM10 65%  
ePM1 60% ePM2.5 60% ePM10 60%  
ePM1 55% ePM2.5 55% ePM10 55%  
ePM1 50% ePM2.5 50% ePM10 50%  
>50% initial efficiency
>50% discharged efficiency
>50% initial efficiency
>50% discharged efficiency
>50% initial efficiency
No discharge requirement
No discharge requirement


Note: ISO16890 demands a minimum (discharged efficiency) of 50% for ePM1 and ePM2.5 rated filters.

Air filter elements according to the ISO 16890 series are evaluated in the laboratory by their ability to remove aerosol particulate expressed as the efficiency values ePM1, ePM2,5 and ePM10. The air filter elements can then be classified according to the procedures defined in this part of ISO 16890.

The particulate removal efficiency of the filter element is measured as a function of the particle size in the range of 0,3 µm to 10 µm of the unloaded and unconditioned filter element as per the procedures defined in ISO 16890-2.

After the initial particulate removal efficiency testing, the air filter element is conditioned according to the procedures defined in ISO 16890-4 and the particulate removal efficiency is repeated on the conditioned filter element. This is done to provide information about the intensity of any electrostatic removal mechanism which may or may not be present with the filter element for test.

The average efficiency of the filter is determined by calculating the mean between the initial efficiency and the conditioned efficiency for each size range. The average efficiency is used to calculate the ePMx efficiencies by weighting these values to the standardized and normalized particle size distribution of the related ambient aerosol fraction.

When comparing filters tested in accordance with the ISO 16890 series, the fractional efficiency values shall always be compared among the same ePMx class (ex. ePM1 of filter A with ePM1 of filter B).

Air Quality in Areas Served by Air Handling Units

The recommended annual average limit values for selecting filter classes according to WHO:

  • Annual average for PM2.5 < 10 μg/m3
  • Annual average for PM10 < 20 μg/m3
  • Currently there are no recommendations for PM1


Eurovent Association recommends (based on BS EN 16798-3) three defined categories for outdoor air (ODA) and five for supply air (SUP).

ODA1 - Clean air, outdoor air, which is rarely or only temporarily contaminated with dust. The annual average according to the guidelines (2005) of the World Health Organization (WHO) for PM2.5 = 10 µg/m3 and for PM10 = 20 µg/m3.

ODA2 - Contaminated air, outdoor air with high particle concentration. This already applies if the WHO guidelines are exceeded by a factor of up to 1.5 in the annual average PM2.5 ≤ 15 μg/m3 and PM10 ≤ 30 μg/m3.

ODA3 - Highly contaminated air, outdoor air with very high particle concentrations. Here the WHO guidelines are exceeded by more than 1.5-fold in the annual average. Values of PM2.5 > 15 μg/m3 and PM10 30 μg/m3 apply.

ODA (Outdoor Air) and SUP (Supply Air) are the abbreviations for outdoor-air and supply-air quality.

Recommended minimum ePMx filtration efficiency depending on ODA and SUP category:

      Areas with high hygienic requirements Areas with medium hygienic requirements Areas with basic hygienic requirements Areas without hygienic requirements Production areas of heavy industry
  PM2.5 PM10 SUP1 (ePM1) SUP2 (ePM1) SUP3 (ePM2.5) SUP4 (ePM10) SUP5 (ePM10)
ODA1 ≤ 10 ≤ 20 60 % 50 % 60 % 60 % 50 %
ODA2 ≤ 15 ≤ 30 80 % 70 % 70 % 80 % 60 %
ODA3 > 15 > 30 90 % 80 % 80 % 90 % 80 %
      Areas with high hygienic requirements such as   hospitals, pharmaceutical industry and manufacturing of food products Areas continually used such as kindergartens, offices,   hotels, residential buildings,    theatres, cinemas or concert halls Areas that are temporarily used by persons, such as   shopping centres, washrooms, server rooms or copy rooms Areas that are only briefly in use by persons, such as   toilets, warehouse facilities or staircases Areas that are rarely used by persons, such as parking   garages, computer centres, or waste disposal sites


Please find below a table containing commonly used filters in air handling units and their new classification under ISO 16890.

Old EN779 Filter Classification New ISO 16890 Filter Classification
G4 Pad Filter (Media Roll) ePMCoarse 60%
G4 Pleated Panel Filter ePMCoarse 65%
M5 Pleated Panel Filter ePMCoarse 85%
F7  Pleated Panel Filter ePM1 55%
M6 Synthetic Bag Filter ePM10 70%
F7 Synthetic Bag Filter ePM1 50%
F8 Synthetic Bag Filter ePM1 70%
M6 Rigid Bag Filter ePM10 70%
F7 Rigid Bag Filter ePM2.5 55%
F8 Rigid Bag Filter ePM1 70%
F9 Rigid Bag Filter ePM1 80%



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