Radon

Last updated on: 04/14/2010

Radon is naturally-occurring radioactive gas, produced primarily by granitic and volcanic rocks. This transparent, odourless gas is present across the surface of the planet and is the primary cause of natural radiation in France. It is responsible for an estimated 2,500 to 3,500 lung cancer deaths each year. It can accumulate in enclosed spaces, including homes. Exposed buildings should therefore be aired and ventilated. Measure 12.6 of the 2009-2013 Cancer Plan involves "Providing better information on the risks associated with radon" and action 40 of the PNSE 2 aims to reduce "exposure to radon in the home". In particular, this action provides for the compilation of a new radon action plan for the period 2009-2013.

Why is radon carcinogenic?

Radon atoms decay and produce substances that emit what is known as ionising radiation. This radiation passes through tissues, such as the lungs and bronchial tubes and can lead to lesions in the body's cells and cause gene mutations. It is therefore carcinogenic. The substances that radon emits accumulate in the dust in the air, which then passes into the body during respiration. The skin is thick enough not to be affected but this is not the case with the bronchial tubes and lungs. Several decades can pass between exposure to the radiation and the appearance of cancer. The risk of lung cancer increases with the concentration of radon in the air and the length of time this air is breathed.
Radon is the primary cause of natural radiation in France. It accounts for just over a third of average exposure to ionising radiation. In the open air, the quantity of radon gas is so low that it poses no health risks. However, in a confined space (in mines, homes and buildings), radon can accumulate and reach relatively high levels of concentration.

In mines
In uranium, uranium-bearing ore and phosphate mines, for example, miners may be exposed to particularly high levels of radon. Currently, the primary method for preventing this risk is to ventilate underground mine passages.

In homes
In homes, the main source of radon comes from the ground on which the home is built. Radon can infiltrate the home through trodden earth, cracks in the walls, joints, etc. High concentrations are generally found in areas of granitic rocks, certain volcanic rocks and some types of schist. As a result, central France, Brittany, the Vosges Mountains, the Alps and Corsica are the most exposed areas. Radon measurement programmes have been conducted by the French Institute for radiological protection and nuclear safety (IRSN) to measure the average annual level of radon in homes in France. According to the results, 2% of homes require corrective action.

Collective prevention measures

A certain number of measures have been taken in France to reduce the effect of radon on health. Many of these form part of the National Health Environment Action Plan (PNSE). Since 2004, public spaces have been subject to a regulation requiring the owners of premises open to the public to measure radon concentration levels in certain areas of the country. Those premises currently covered by this regulation are:

• educational establishments, including boarders' accommodation
• healthcare and social establishments with accommodation facilities
• thermal establishments
• penal establishments.

According to the public authorities, there are three distinct levels of exposure:

• below 400 Bq/m3: this situation does not require any particular corrective action
• between 400 and 1,000 Bq/m3: basic corrective action should be taken
• above 1,000 Bq/m3: potentially wide-ranging corrective action must be taken quickly as this may represent a high level of risk.

Heavily-populated establishments may be closed until the necessary corrective action is taken.

Individual prevention measures

Radon concentration levels can be measured simply and cost-effectively using a dosimeter. This involves placing a detector in a room for a period of two weeks to several months. This may be a suspected room or one in which the individual concerned spends a large amount of time. There are also companies that can perform this assessment. The French Institute for Radioprotection and Nuclear Safety (IRSN) also offers this service and has the necessary expertise to handle complex cases. Excessively high radon concentrations can also be reduced:

• by improving the airtight protection between the ground and the building: replacing existing basement floors, particularly in buildings built on trodden earth, repairing cracks in walls and floors, ventilating basement floors, etc.

• by ventilating homes and buildings to provide a fresh air supply: natural or mechanical ventilation.