Radon

Radon is a radioactive noble gas that is formed by the decay of the uranium from the terrestrial crust. This gas from natural source is odorless, colorless and tasteless. Radon is diffused from soil and water in the air and accumulates slowly in closed spaces. Radon can be found in elevated concentrations in buildings, and if inhaled, can damage lungs by further radioactive decay. A long time exposure can provoke lung cancer.

The contamination of a building with radon depends on several factors like its concentration in the soil and the permeability of the later. The more permeable is the soil, the easiest the radon diffuses to the surface. Therefore, houses situated above fractures, karstic systems or rock slides are more exposed than houses situated above clay layers. Moreover, the building features (construction-process, surface cracks in contact with the soil and ventilation system) are also important.

Radon is hazardous in whole Switzerland. The Alps and the Jura are especially exposed, but high radon concentrations are also found in buildings from the Swiss plateau.