The geogenic radon potential

The activity concentration of radon (${}^{222}$Rn) indoors depends on a variety of different factors. Besides the building characteristics, the soil under the building is the most important source of indoor radon. To compare different locations or regions with different soil structures, it is useful to use the "geogenic radon potential," a function of the radon activity concentration in the soil air and the permeability of the soil. This quantity can be understood as a measure of the amount of radon that a soil releases. In addition to making different locations comparable, the geogenic radon potential can also be used as a basis for designating areas where, according to the StrlSchG, the radon concentration in indoor air exceeds the reference value of 300 Bq/m${}^3$ "in a considerable number of buildings."