Radon potential in Germany

The radioactive noble gas radon can cause lung cancer. When radon is present in the soil in high concentrations and the soil is permeable, leaks in the building can cause a great deal of radon to enter the interior of buildings and accumulate there.

The concentration of radon escaping from the soil and its potential to penetrate into houses is known as the "radon potential". Its magnitude depends on two factors:

• How much radon is concentreted in the soil and
• How permeable (to gas) the soil is.

Radon potential: basis for the designation of radon areas

The radiation protection legislation (Strahlenschutzgesetz) requires regions with particularly high radon concentrations in indoor spaces to be designated as radon precautionary areas. In these areas

• the radon concentration in workplaces must be evaluated by taking radon measurements and
• measures for radon protection must be applied within buildings.

The radon potential of a region is an important basis for the establishment of radon precautionary areas.

Estimation of radon potential throughout Germany

Because every square metre of Germany cannot be measured for its radon concentration and gas permeability, the Federal Office for Radiation Protection (BfS) has developed a method to estimate the radon potential throughout Germany.

From 1995 to 2001, the radon concentration of the soil and its permeability was measured at around 3,700 locations in Germany. Using these values, the radon potential was also estimated for areas between these measurement points. Using geological knowledge, the measurement values were compiled into a map of Germany and then similar measurement values in regions close to one another were connected together. This template was then analysed and improved using mathematical simulations for the areas between the measurement points.

The method is based on procedures that are used in a similar form for the discovery of raw materials: Possible depositories are identified on the basis of a few sample boreholes. In earthquake research too, measurements and knowledge of subsurface geological properties are used to identify the potential earthquake risk of a given region.

Prognosis: regional radon potential

Prognosis of radon potential in Germany

The mathematical simulation methods have been used by the BfS to create a map of Germany in which the radon potential of regions is shown by colour.

The map provides an initial estimation of the radon situation in a region. The actual level of radon at a particular location can be assessed exactly only by taking air measurements close to the soil or by measuring the radon concentration within a building.

The map of radon potential in Germany allows the BfS to support the Federal Government and the states in developing a radon action plan to provide efficient strategies to protect against high indoor radon concentrations.