Indoor radon measurements and dose assessment for workers in kindergartens in southern poland

• Increased radon concentrations observed in southern Poland. • Concentration of radon activity in building depends on the geological structure. • Data showed features like basements, ventilation key to indoor radon levels. • In many cases, the annual effective dose for workers exceeded 1 mSv. In 2024, a study was carried out to measure indoor radon concentration in 58 kindergartens located in the southern region of Poland. The primary aim was to estimate the exposure of kindergarten workers by measuring the radon activity concentration and to calculate the annual effective dose for workers. Annual effective dose calculations, based on maximum radon activity values, showed that in 9 out of 11 counties the dose exceeded 1 mSv/year. The measurements were carried out in accordance with the guidelines laid down in the national regulations. TASTRAK detectors were used for measurements. In rooms situated in basements or on ground floors, which were identified as workspaces, three detectors were deployed per room and remained in place for one month during the heating period. The detectors covered a total of 289 measurement points in 58 buildings. 8 results were identified as being below the detection threshold, 249 results (86 %) indicated radon concentration below 300 Bq/m³, 32 measurement points (11 %) recorded radon concentration exceeding 300 Bq/m³, with a maximum value of 1034 Bq/m³. Additionally, each facility participated in a radon-related survey designed in alignment with the International Atomic Energy Agency Safety Report Series No. 98, titled “Design and Conduct of Indoor Radon Surveys.” The collected data encompassed various building characteristics such as construction materials, age, basement presence, as well as the heating and ventilation infrastructure, and the nature of the surrounding soil.