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The risk of radon exposure must be considered by businesses in their risk assessment.
This is why we offer an overview of the main legal obligations on this topic.
What is radon?
Radon is a naturally occurring radioactive gas, resulting from the decay of uranium and radium.
It forms underground and is classified as carcinogenic*;
Radon is present throughout France and at high concentrations in granitic and volcanic regions (e.g., Armorican Massif, Massif Central, Corsica, Vosges, etc.).
*Studies show that radon exposure in France is the second leading cause of lung cancer after smoking.
The concentration of radon in a building's air depends on the characteristics of the soil, but also on the building itself and its ventilation.
What is the reference level?
It is the level of radon activity concentration above which it is deemed inappropriate to allow workers to be exposed to ionizing radiation, even if it is not a limit that cannot be exceeded.
It is set at 300 Bq/m3 as an annual average.
How are municipalities classified?
The radon potential of municipalities is set by the decree of June 27, 2018 and shown on a map available on the website of IRSN (Institute for Radiological Protection and Nuclear Safety). You will find municipalities classified into 3 categories:
- Zone 1: areas with low radon potential;
- Zone 2: areas with low radon potential but where specific geological factors can facilitate the transfer of radon into buildings;
- Zone 3: areas with significant radon potential.
Who is affected by radon regulations in the workplace?
This applies to businesses whenever workers (including self-employed individuals) are likely to be exposed to a risk due to ionizing radiation of natural or artificial origin, particularly professional activities carried out:
- in the basement or on the ground floor of buildings located in areas where radon exposure is likely to harm workers' health
- in certain specific workplaces, the list of which is set by the order of June 30, 2021 (underground mines and quarries, tunnels, underground car parks, thermal establishments, etc.)
These employers must assess the radon risk.
How to assess radon risk outside specific workplaces?
How to assess radon risk in specific workplaces?
The employer must implement an alert system if there is no ambient radon volumetric activity monitoring system for each worker or team performing short-term tasks where the preliminary radon risk assessment cannot confirm that the reference level will not be exceeded.
What to do if I have identified a radon zone?
If a radon zone is identified, the employer must:
- appoint a radiation protection advisor;
- report the radon zone;
- carry out an initial verification by measuring the radon activity concentration in the air in radon zones when the facility is commissioned or following any significant change in working conditions that could affect workers' health and safety. This verification is carried out by an accredited body or a body approved by the ASN. In specific workplaces, if the employer decides to establish a radon zone throughout the entire workplace, an initial verification is not required.
- periodically renew this verification (at least every 5 years or if the radon activity exceeds 1000 Bq/m3, annually) which is then carried out by the radiation protection advisor;
- provide workers with personal protective equipment when collective protection measures are insufficient;
- train exposed workers;
- assess the individual exposure of workers accessing these areas prior to their assignment to the workstation and issue them an authorization;
- implement dosimetric monitoring of the worker (via appropriate delayed-reading dosimeters) when the effective dose is likely to exceed 6 mSv over 12 months, and provide them with enhanced individual health monitoring.
What about Public Access Buildings (ERP)?
Additional obligations apply to certain Public Access Buildings (e.g., prisons, thermal baths, educational institutions), such as:
- Periodic measurements by IRSN or approved organizations
- Corrective actions,
- Display of results, etc.
Radon exposure: conclusion
All companies must assess the risk of radon exposure for their workers and, more specifically, record the results of their risk assessment in their single risk assessment document.
Note: this assessment and the measurement results must be submitted to health professionals (occupational physician, collaborating physician, nurse, etc.) as well as to the Social and Economic Committee (CSE).
Photo credit: Luca Maffeis