Modelling the impact of building materials and water use on indoor radon concentration

This study numerically assessed the contribution of secondary sources—building materials and water—to indoor radon concentrations using the MATHIS-QAI model. A meta-analysis established typical radon levels from soil, materials, and water, which were then integrated into a sensitivity analysis across five radon potential levels. Results showed that secondary sources can significantly influence indoor radon under low soil radon conditions if their own potentials are elevated. In contrast, soil remains the dominant source when its radon potential is high, especially due to direct contact with building foundations. Multi-zone modeling revealed that on upper floors, materials and water may surpass soil gas as primary contributors. The model provides a valuable framework for evaluating radon mitigation strategies. However, limitations include fixed transfer parameters and lack of building-specific variability.