Radon measurements are currently under way along newly discovered faults in the northern Upper Rhine Graben near Groß-Gerau. Measurements of radon activity in soil air should show if the disruptions are recently active. In the process, it is difficult to compare the measurements of soil types, with different permeability, without logging the actual air flow. It is intended therefore to develop a standardised method which combines the measurement of radon with the detection of CO
in soil air. Outcomes will be used for correlation with radon concentrations in the indoor air of buildings in the region of Darmstadt (Kuhn 2013), which is situated in the tectonically active northern Upper Rhine Graben, in order to evaluate geogenic radon in the area.