The main causes of indoor pollution are:
Biological contaminants
Chemical pollutants

Biological contaminants

Biological contaminants are the primary cause of diseases related to indoor air.

What are the sources of these biological contaminants?

• Biological pathogens (moulds and pathogenic bacteria) proliferate under conducive climatic conditions such as:
o poor ventilation
o a lack of ventilation
o excessive dampness
o presence on the walls or woodwork of moist areas (thermal bridges)
o presence of a very large number of potted plants

• Pets that live with us, can be a source of allergies:

dogs, cats and other domestic pets. It is therefore essential before adopting a pet, to check whether the people who will live with the animal are allergic to it;
mites and insects that proliferate in mattresses and armchairs, in the soil of potted plants, in pipes and basements, next to the garbage, etc.

For more information on moulds that contaminate our indoors, you can view the Scientific Institute of Public Health website (ISP). It is the reference Belgian laboratory in this respect.

Chemical pollutants

The indoor environment contains various chemical pollutants in varying amounts. In general, the present concentrations do not pose any problems. However, some products, activities, appliances, are sources of pollution. Especially, when they are too many, too diverse, misused, dysfunctional or poorly maintained, this leads to health risks.

Besides tobacco smoke, the main sources of chemical pollutants are the outdoor air (e.g.: external particles tend to accumulate inside), building materials and furniture, cleaning products, combustion appliances, etc.

For more information on some pollutants:
• VOC (indoor air)
• Formaldehyde
• Carbon Monoxide (CO)
• Particles
• Nitrogen oxides

6.6.2. Effets_exposition_Causes et sources_politiques_EN_