Dynamics in the radon index measurements at a specific test site

The study deals with the evaluation of the dynamic of the radon index in one pilot site based on second-time pilot investigations of the radon index in Bulgaria. In situ measurements of the radon concentration in soil gas, and soil permeability at three polygons: one over and two – close to fault zone have been performed in October 2020 and October 2022. The results show that higher radon content is detected in the fault zone in both cases.