How much radioactive radon gas is in the ground? And how much of it potentially ends up inside buildings? This is now shown by new maps from the Federal Office for Radiation Protection. The maps created on the basis of new measurements and machine learning give a more precise picture of the radon exposure in Germany and can thus reveal where protective measures are necessary. Elevated levels of radon can trigger lung cancer.
The radioactive gas radon is formed naturally by the decay of uranium and thorium in the bedrock. The gas can then rise from the ground and also penetrate into buildings. If you live or work for a long time in rooms with increased radon levels, the risk of developing lung cancer increases. In Germany, radon pollution is particularly high where granitic rocks with a higher uranium content occur, such as in the low mountain ranges of southern Germany.
Map shows radon levels in the soil…
The Federal Office for Radiation Protection (BfS) regularly carries out measurements to find out in which areas of Germany the radon levels in the soil and buildings could be potentially high. The radon concentration in the soil and its gas permeability are determined by sensors at almost 6,300 measuring points. For the current map, BfS scientists evaluated radon measurement data from 1992 to 2020 and included information about geology, soil properties and climate.
The result is a map of Germany that shows the expected radon concentration in the soil air at a depth of one meter with a resolution of one kilometer by one – much higher resolution and more reliable than before. The reported values have a 90% probability that the actual values are equal to or less than. The risk that the load on a small, local scale is higher than stated is therefore only ten percent, as the BfS explains.
…and the potential exposure in buildings
A second map shows the so-called radon potential. This indicates how much radon gas can escape from the ground and potentially enter the interior of houses. The value of this potential depends on the radon content of the subsoil, but also on the gas permeability of the soil. The latter results from the geological composition of the subsoil.
The BfS researchers have developed a method with which the radon potential can also be estimated for areas between the measuring points. For this purpose, the measured values are grouped into classes based on their geology. With the help of mathematical simulations and machine learning methods, the resulting patterns are then extrapolated for the areas with similar geology lying between the measuring points.
How high the radon concentration is inside an individual building or in the ground of an individual property cannot be read from the map, as the BfS emphasizes. Such a small-scale exposure can only be determined with a radon measurement. However, the new maps can provide information about where such a measurement makes sense and is advisable.
The new cards are visible here.
Source: Federal Office for Radiation Protection