A comparative analysis of indoor radon activity concentrations in Romanian houses and educational institutions.

Radon accumulation in indoor environments poses a significant public health concern, especially in educational institutions, where children are particularly vulnerable. This study investigates indoor radon activity concentrations (IRAC) in 198 educational institutions and 266 houses from Cluj-Napoca, Romania, analyzing a total of 1440 rooms. Radon levels were assessed using CR-39 track detectors, with measurements conducted over three and twelve-month periods for educational and residential buildings, respectively. Preliminary results reveal notable differences in IRAC between the two building types, with 24 % of educational institutions and 13 % of houses exceeding the reference level of 300 Bq/m³. Factors such as the presence of basements, construction materials, and ventilation systems were found to significantly influence IRAC. A room-level analysis highlighted that those laboratories and classrooms that were located on lower floors had the highest IRAC, while flooring type and structural barriers played a critical role in mitigation. The study contributes by reinforcing the importance of accounting for building-specific characteristics in radon exposure assessments and highlights the need for tailored mitigation strategies in different building types. Moreover, the findings raise important questions about the representativeness of residential radon maps for public buildings, emphasizing that spatial correlations between the two building types remain low.