European Standard EN13779. Filter Recommendation For Achieving Optimal IAQ.

EN13779 is the nearest thing to an IAQ standard, with built-in recommendations for outdoor air and indoor air which can include particulate and molecular filtration. As a new standard for ventilation and room conditioning systems in non-residential buildings, EN13779 is now a legally accepted standard in all member states of the European Union. The standard sets out to achieve a comfortable and healthy indoor air quality (IAQ) in all seasons of the year at acceptable installation and operating costs, taking into consideration the outdoor air. It represents a major step forward, recognizing the importance of external air in achieving better indoor air quality and/or a healthier environment.

Categories of Outdoor Air According to EN13779

According to EN13779, the outdoor air is categorized in three levels, from ODA 1 (pure air which may be only temporarily dusty) to ODA 3 (very high concentrations of gaseous pollutants and particulate matter).

The application of this classification will depend on the criteria that are being used, as there is currently no uniform global guideline for all pollutants. However, it is clear the potential impact of mixtures of pollutants, rather than just individual pollutants, should be considered in determining the ODA classification. As a reference point, the following approach is suggested:

• ODA 1: applies where the WHO (1999) guidelines or any national air quality standards or regulations are fulfilled.
• ODA 2: applies where pollutant concentrations exceed the WHO (1999) or any national air quality standards or regulations for outdoor air by a factor up to 1.5.
• ODA 3: applies where pollutant concentrations exceed the WHO (1999) or any national air quality standards or regulations for outdoor air by a factor greater than 1.5.

Typical gaseous pollutants to be considered in the evaluation of ODA are carbon monoxide, carbon dioxide, sulphur dioxide, oxides of nitrogen and volatile organic compounds (VOCs). The indoor impact of such outdoor pollutants will depend on how reactive they are.

Particulate matter refers to the total amount of solid or liquid particles in the air, from visible dust to submicron particles. Most outdoor air guidelines refer to PM10 (particulate matter with an aerodynamic diameter up to 10 µm) but there is growing acceptance that, for the purpose of health protection, greater emphasis should be placed on smaller particles.

Categories of Indoor Air According to EN13779

Filter Recommendations According to EN13779

When the pollution level of the outdoor air is classified, EN13779 recommends the right air filtration solution for the preferred indoor air quality, as summarized in the table below (definition of filter classes according to EN779:2012).

* GF= Gas Phase Filters

Gas-phase filters are recommended in areas of category ODA 3. It can also be a good solution in the case of category ODA 2 when there are gaseous pollutants outdoors. It is important to protect the filters from getting wet: the relative humidity should be less than 80%.