Indoor Radon Exposure in Kindergartens and Schools in Serbia

This paper presents the first comprehensive review of radon concentration measurements conducted in educational institutions in the Republic of Serbia. The analysis includes data from the national radon survey conducted in 2019, long-term measurements performed within the national radioactivity monitoring program during the period 2011–2024, a local investigation carried out in the city of Šabac, and other available studies conducted throughout Serbia using different measurement methods (CR-39 detectors, activated charcoal canisters, and continuous radon monitors). During the 2011–2024 period, a total of 303 measurements were performed in kindergartens, primary schools, secondary schools, and universities across seven Serbian cities, while 4133 CR-39 detectors were collected during the 2019 national survey. The survey achieved high coverage of primary schools (87%) and kindergartens (76%), whereas the coverage of secondary schools was only 20%. Measured radon concentrations ranged from minimum values of 5–30 Bq/m3, with average concentrations between 60 and 150 Bq/m3 in most buildings, to a maximum of 2970 Bq/m3 recorded in a primary school. A significant proportion of the indoor radon concentration measurements exceeded the WHO reference level of 100 Bq/m3 (approximately 40%), while a smaller proportion also exceeded the threshold of 300 Bq/m3. The observed spatial variability could be associated with differences in geological conditions, building type, construction materials, and ventilation characteristics. On average, the estimated contribution of indoor radon exposure during occupancy of schools and kindergartens was below 1 mSv/y for children and educational staff. The critical analysis highlights insufficient coverage of certain regions and types of educational institutions, methodological differences among individual studies, and the need for a more rational approach to radon measurement and risk management. The findings indicate the need to move from fragmented and repeated measurements toward an integrated, risk-oriented national strategy based on mass screening, active public involvement, and targeted long-term measurements. Short-term measurements could be used for the initial screening of a large number of buildings, while buildings with elevated radon concentrations would be prioritized for confirmatory long-term measurements and mitigation measures, with the potential use of simple and IoT-based devices for large-scale data collection. Such an approach could provide a practical basis for the further development and implementation of the National Radon Action Plan in Serbia, with the aim of reducing individual and collective risks associated with radon exposure.