Municipality of Wahl: Pilot study on radon

In early 2016, the Radiation Protection Division (Division de la radioprotection - DRP) of the Health Directorate (Direction de la santé) conducted radon concentration measurements in private houses in the municipality of Wahl. Around 200 households volunteered to take part in the pilot study.

Radon is a naturally occurring radioactive gas that is all around us. It can easily escape from shale soil, for example, through cracks in the ground. If a house is not well insulated from the ground, radon can penetrate the building. In that case, the concentration of radon in the house will gradually build up over time. High values that are potentially dangerous to health can therefore often be observed, depending on how well the house is ventilated. Radon is responsible for most of our exposure to natural ionising radiation and, in high concentrations, can contribute to the development of lung cancer. It can become a problem, especially in winter, when houses are centrally heated and often less well ventilated at the same time. It was for this reason that the study was conducted over the winter months.

For the purposes of the pilot study in Wahl, radon detectors were distributed to the participating households, with valuable support from municipal officers. Each household was provided with two detectors. After approximately three months, staff from the DRP collected the detectors to assess the readings. During this visit, the specific features of the houses were recorded. The results were then communicated individually to the study participants.

On 20 July, the DRP presented the results to the local residents at an information meeting. The participants were given advice on how to reduce radon levels in their homes, and had the chance to take part in a final question-and-answer session on the topic.

Measurements in the 6 districts included in the study revealed average radon concentrations of between 126 Bq/m³ and 263 Bq/m³. Readings in excess of 1000 Bq/m³ were also observed. Generally, radon concentrations can be reduced using a variety of remedial techniques. The data that was collected has been used to highlight important factors that play a role in the presence of radon, such as specific geological features, including the type and age of the rocks, but also construction factors, such as the type of foundation, subsoil or even ventilation of the rooms.

Residents whose readings are particularly high (above 600 Bq/m³) can contact the DRP on 247 85 671. The most appropriate remedial measures, which are generally affordable, should be selected on a case-by-case basis.