What is an air filter?

The Netherlands is urbanized, densely populated and surrounded by the many highways and railroads. Not exactly conducive to outdoor air quality. Air filters filter out harmful particles and gases from the outside air. In addition, the filters contribute to a longer life of ventilation systems and prevent unnecessary energy loss due to contamination of heat exchangers and fans. Thus, air filters are necessary for healthy indoor air.

Air filters, for example, offer protection against particulate matter. The Dutch are becoming increasingly aware of the importance of clean air. Respiratory infections and other respiratory diseases are receiving more and more attention in the media, emphasizing the importance of choosing the right air filter. Everyone likes to work in a safe environment, and clean air is an important part of that.

What types of air filters are there?

There are three different types of air filters:

  • The dust filter

A dust filter is used to capture dust particles with a minimum size of 0.3 microns (one thousandth of a millimeter). Thereby, a dust filter can be chosen in a coarse or fine variant. Examples include: panel filters, compact filters and bag filters.

  • (H)EPA filters

A common filter is the (H)EPA filter. (H)EPA stands for (High) Efficiency Particulate Air filters. Another name is Absolute filters. These filters are used to capture airborne particles up to a size of 0.3 microns. (H)EPA filters are often used in operating rooms and clean rooms.

  • Molecular filters

Molecular filters remove molecular pollutants from the air. These include harmful gases such as NOx (nitrogen oxides) and NH3 (ammonia) and baking and sewage odors.

Standards

Filters are tested according to international standards and can be compared with each other based on their properties. Most filters are tested according to the global standard ISO 16890. This standard replaced the European standard EN779:2015 in 2017. Depending on their efficiency, (fine) dust filters are assigned to a certain filter class according to the ISO 16890 standard.

Filter classes

These filter classes can be divided into four main groups: ISO ePM1, ISO ePM2.5, ISO ePM10 and ISO Coarse. Within the main groups, there is a breakdown by the percentage captured by a filter. To be classified within a group, a filter must capture a minimum of 50% of particles.

Thanks to the ISO 16890 standard, it has become clearer which filter class is most suitable for certain conditions. The designations PM10, PM2.5 and PM1 correspond to particulate matter values measured by governments worldwide. The World Health Organization (WHO) also uses these designations.

Advisory Guideline

To determine exactly what the right air filter is, professionals are no longer entirely dependent on the experts in the market. Standards such as the NEN EN 16798-3 and the directive 'Air filters for air handling systems' give advice on which air filter is best to install.

Eurovent

Eurovent has also established advisory guidelines (REC 4/23-2018). These guidelines recommend the minimum filter classes required to create healthy indoor air in specific conditions. This takes into account the degree of polluted outdoor air on site and the use and occupancy of the building for which the air needs to be filtered. Threshold values here are the strict guidelines for healthy air as used by the WHO.

RIVM

RIVM has developed a system that indicates the extent to which air quality at a given time of day affects health. This information provides an opportunity to minimize exposure to air pollution. Curious about air pollution in a particular area? Consult the Air Quality Index.

 

  • Healthy air guidelines based on WHO advisory standards:

    Outdoor air quality Supply air classification (supply air class).
    PM values (μg/m3) SUP1 (highest)
    PM2.5 ≤2.5
    PM10 ≤5    		 SUP2
    PM2.5 ≤5
    PM10 ≤10    		 SUP3
    PM2.5 ≤7.5
    PM10 ≤20    		 SUP4
    PM2.5 ≤10
    PM10 ≤20    		 SUP5 (lowest)
    PM2.5 ≤15
    PM10 ≤30

     

    Minimum recommended filter class (ISO 16890).
    ISO ePM1 ISO ePM1 ISO ePM2.5 ISO ePM10 ISO ePM10
    ODA 1 70% 50% 50% 50% 50%
    ODA 2 80% 70% 70% 80% 50%
    ODA 3 90% 80% 80% 90% 80%

  • Outdoor air (ODA)

    ODA 1: (PM2.5 ≤ 10 μg/m3 and PM10 ≤ 20 μg/m3)
    refers to outside air that is only temporarily polluted.

    ODA 2: (PM2.5 ≤ 15 μg/m3 and PM10 ≤ 30 μg/m3)
    refers to outdoor air with high concentrations of particulate matter.

    ODA 3: (PM2.5 >15 μg/m3 and PM10> 30 μg/m3)
    refers to outdoor air with very high concentrations of particulate matter.

  • Supply Air (SUP):

    Class Description Examples

    SUP 1
    (PM2.5≤10μg/m3 & PM10≤5μg/m3)

    		 Industrial toapplications with demand for high hygienic requirements:
    • Hospitals
    • Pharmaceutical industry
    • Electronics

    SUP 2
    (PM2.5≤5μg/m3 & PM10≤10μg/m3)

    		 Rooms with permanent occupancy:
    • Childcare
    • Schools
    • Offices
    • Hotels
    • Housing
    • Conference Rooms
    • Meeting rooms
    • Exhibition Halls
    • Cinemas
    SUP 3
    (PM2.5≤7.5μg/m3 & PM10≤15μg/m3)
    		 Rooms with temporary occupancy:
    • Sheds
    • Shopping malls
    • Laundry rooms
    • Copy rooms
    • Server rooms

    SUP 4
    (PM2.5≤10μg/m3 & PM10≤20μg/m3)

    		 Rooms with short occupancy:
    • Toilets
    • Storage spaces
    • Staircases
    SUP 5
    (PM2.5≤15μg/m3 & PM10≤30μg/m3)
    		 Rooms without occupancy:
    • Manufacturing areas with heavy industry such as steel mills,
      smelters and foundries.

New class designation

Unfortunately, it is not possible to translate the old class designations (EN779:2012) to the new class designations (ISO 16890). This is because the difference in test methods is too great. The test results depend, among other things, on the type of filter and the type of filter cloth. Ask your air filter specialist which filter class your air filters comply with.

Maintenance

Systems, including air filters, must be designed and installed so that they can be inspected and maintained monthly. Inspection should be performed by a professional to ensure optimal operation.

  • When should air filters be replaced?

    • For visual leaks and damage
    • When soaking the air filter
    • After construction or remodeling of the plant
    • Upon reaching the specified end resistance (end resistance specified by AHU manufacturer or system supplier)
    • Preferably, the change of a filter takes place after the pollen season in autumn and/or after the heating season in spring

  • When changing air filters, pay attention to the following points:

    • Store spare filters dry and clean in the original packaging
    • While changing air filters, wear protective clothing, such as a mouth mask and gloves
    • Carefully pack the dirty air filters to prevent the escape of contaminants
    • Install the new air filter according to the filter manufacturer's instructions to avoid damage, such as wedged bags
    • Check the zero value of the differential pressure gauge and the operating-hour counter
    • For each air filter section, record on a service card the date of the filter change, the resistance of the new filters, the next filter change, and the name of the performer
    • Disposal of the dirty air filter (outside air and recirculation) can be done as industrial waste

    Filters that have collected harmful substances must be disposed of as chemical waste. Always comply with environmental regulations when doing so.

An initiative of Binnenklimaat Nederland TVVL SWP
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