Radon-containing habitat

Verified 16 March 2022 - Directorate for Legal and Administrative Information (Prime Minister)

Radon is a naturally occurring radioactive gas that can be harmful to health. Radon is usually present in certain geographic areas. Work may be required to reduce radon in your home. It is not possible to eliminate it completely. Assistance from the National Housing Agency (Anah) can be given to you when the work is necessary to reduce the presence of radon in your home.

Radon is a naturally occurring radioactive gas generally found in basements.

Less commonly, it can also be present in building materials or running water.

Radon poses health risks. Indeed, in the long term, the inhalation of radon leads to an increased risk of developing lung cancer. This increase is proportional to lifetime cumulative exposure.

Radon occurs mainly in the following geographic areas:

  • Brittany
  • Corsica
  • Central Massif
  • Vosges

One mapping can be consulted to find out if your municipality is concerned.


these areas do not necessarily indicate the presence of radon in your home, as it depends on multiple factors. Examples: the tightness between the building and the ground, the rate of renewal of the indoor air.

There is no requirement for radon risk control for residential buildings.

However, it is possible to carry out verifications yourself by obtaining a dosimeter from the market.

For the checks to be effective, they must be carried out in the main living rooms, over a period of several weeks and preferably over the winter period.

When the dosimeter result is greater than 300 becquerels (BQ)/m3Yes, there is a risk to your health.

In this case, it is necessary to carry out work or to put measures in place.

These measures may include:

  • Installation of a mechanical ventilation system or frequent ventilation of all rooms in the dwelling by opening the windows
  • Renovation of basements (e.g. waterproofing) and pipes. The work must be carried out by companies competent in masonry or waterproofing and more particularly in climate engineering.


radon levels can be reduced, but not eliminated.

The National Housing Agency (Anah) can offer you financial assistance to carry out radon reduction work in your home. For that, you must respect certain conditions (age of the dwelling, conditions of resources...).