Factors influencing radon risk in mining areas: In Situ verification of multi-criteria tool.

The main source of radon penetrating buildings is the ground. Both the concentration of natural radioactive nuclides and the physical properties of soil and rock, which facilitate the migration of radon, are important. In the Upper Silesian Coal Basin (Poland), many years of mining activity have caused the disintegration of the geological environment, hydrological disturbances, and damage to buildings located within continuous and discontinuous deformation areas. These phenomena may facilitate the transport and penetration of radon into residential and workplace premises. This paper presents a risk assessment of elevated radon activity concentrations based on a multifactorial analysis, taking into account hazards caused by mining activities, as well as natural and technical factors. A set of criteria and an assessment of the significance of each criterion were proposed, adopting ranges of values and limits established by regulations or determined arbitrarily. The model was calibrated and subsequently validated using a series of in situ measurements demonstrated an overall classification accuracy of 67%, with a low false negative rate (6%), which is particularly important for environmental risk assessment. In addition, the Cohen's kappa coefficient increased from 0.12 to 0.36 after model calibration, indicating improved agreement between theoretical predictions and field measurements. The proposed approach can therefore be used as a preliminary screening tool for identifying radon-prone areas in mining and post-mining regions and for supporting the planning of targeted in situ radon measurements.