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Indoor air quality: the main pollutants

The choice of an eco-passive building project can be motivated by various issues, including environmental protection, lower energy bills and indoor comfort improvement. The latter is a major issue, as health in the home is becoming a central part of our daily lives. Find out which are the main indoor air pollutants, their consequences on health and good practices to reduce their impact.

In Europe, the WHO estimates that air pollution is responsible for around 600,000 deaths per year, of which almost 20% are due to indoor air pollution. On average, we spend more than 80% of our time in enclosed spaces (housing, transport, offices, schools, etc.), making indoor air quality a major issue. 

But where does this pollution in our homes come from?

As the French Agency for the Environment and Energy Management (ADEME) reminds us in its booklet “Un air sain chez soi” (“A healthy air at home”), the sources of pollution are diverse and can be classified into three categories:

  • Equipment: combustion appliances such as stoves or fireplaces, boilers and ventilation.
  • Materials: insulation, paint, varnish, glue, textiles, etc…
  • Occupants’ activities: use of household appliances (cooking, hoover, washing machine, etc…), waste storage, smoking, cleaning products, etc…

Among these three sources of pollution, the main pollutants are the following:

  • Carbon monoxide: This is a deadly, colourless and odourless gas that is released by poorly maintained combustion heating or hot water appliances.
  • VOC and SVOC (Volatile and Semi-Volatile Organic Compounds): These are substances that evaporate into the ambient air and come from building or decoration materials, treated furniture, paints, cleaning products, etc…
  • Biological pollutants: These come from living organisms such as mould, dust mites,…
  • Particles and fibres: These include dust particles in the air (pollen, allergens, etc…) and fibres usually found in insulation (glass wool, cellulose, etc.).

Exposure to these pollutants can have dramatic consequences, particularly in the case of carbon monoxide poisoning. For other pollutants, the consequences will depend on the degree and duration of exposure, as well as on the exposed profile (elderly people, children, etc…). In the case of high exposure, the symptoms may be headaches, coughing, nausea, respiratory problems and irritation. Lesser but repeated exposure can have long-term effects and lead to chronic conditions such as asthma and allergies.

To limit indoor air pollution, there are a number of good practices. Among the easiest and most essential: air your home twice a day for about ten minutes and each time the occupants’ activity alters the air quality (cooking, washing up, showering, etc…). Ideally, opt for a dual-flow recovery ventilation system, used in passive houses, to facilitate the renewal of the indoor air. The dual-flow recovery ventilation system extracts polluted air from areas such as the kitchen, bathroom and toilets and provides new, clean air (thanks to filters) to living rooms and bedrooms. This system limits humidity and the development of moulds, which are responsible for many respiratory problems, and minimises the concentration of pollutants. However, be careful with the ventilation system maintenance, by changing the filters once or twice a year. This recommendation also applies to all domestic appliances. Another recommendation for good indoor air quality is to use health friendly building materials that are free of varnish and VOC. In the case of passive building, the health risk is one of the criteria for the choice of insulation and cladding materials. Finally, to limit pollutants in the home, choose your cleaning products and furniture carefully. There are labels, such as the European EU Ecolabel, which recognises products that are environmentally and health friendly.

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