Risks and Severity

We spend most of our time indoors. Our activities, the objects and the materials that surround us release substances into the air that can be harmful to health. 

What are the risks of indoor air pollution?

Indoor air pollution can pose many health risks, including:

  • carbon monoxide poisoning
  • respiratory infections
  • allergies
  • cancer (radon, fine particles)
  • etc.

Carbon monoxide poisoning

  • Carbon monoxide (CO) is a colorless, odorless, non-irritating but toxic and lethal gas. It usually comes from poorly maintained heaters: due to lack of oxygen, combustion is incomplete and gas escapes.
  • Carbon monoxide diffuses rapidly into the environment and acts as an asphyxiating gas: when inhaled, it takes the place of the oxygen in the blood and can kill in minutes.
  • More information on carbon monoxide poisoning can be found at Belgium.be

Respiratory infections

Several studies have shown that damp and moldy environments affect the immune system, especially when it comes to more fragile population groups, such as children, among which cases of respiratory infections such as bronchiolitis are increasing. 


In recent decades there has been an increase in allergies in children, with a high prevalence of allergic rhinitis and asthma.  
The mechanisms behind the appearance of allergies is complex but several avenues can be explored:

  • outdoor pollution (fine particles)  
  • and indoor pollution (volatile organic compounds, fibers, dust, allergens from animal hair, cockroaches, mites, molds, etc.)

Mite allergens affect a large number of people in the population. They are known to be mostly present in mattresses. But other mites develop in damp buildings. Most moldy surfaces harbor them. Recent epidemiological studies also indicate a very significant relationship between mold exposure and asthma.


Some substances found in the air have been shown to be carcinogenic:

  • cigarette smoke
  • furniture or insulation coatings (formaldehyde, benzene, flame retardants)
  • radon
  • fine particles found in outdoor air (transport, industry, etc.) and indoor air (outdoor pollution, heating and cooking systems using coal or wood)


In collaboration with the regions, Sciensano carries out sampling and analysis on a number of microbiological pollutants (bacteria, fungi, molds) in private (residential) and public places.

Scientific reports

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