SYSTEMATIC INDOOR RADON AND GAMMA-MEASUREMENTS IN KINDERGARTENS AND PLAY SCHOOLS IN SLOVENIA

Systematic measurements of indoor radon concentrations and gamma dose rates were carried out in the 730 kindergartens and play schools in Sl ovenia that, together, care for 65,600 children. The main method for i ndoor radon measurement was direct sampling in alpha scintillation cel ls, but in cases with an increased instantaneous radon concentration, the additional methods of track-etch detectors and alpha spectroscopy were applied. In 528 kindergartens and play schools (72%), radon conce ntrations were below 100 Bq m(-3), with a geometric mean of 58 Bq m(-3 ). In 16 kindergartens and play schools (2.2%), radon concentrations e xceeded 800 Bq m(-3). In all cases, the main reason for a high indoor radon concentration was the geological structure of the soil. Gamma do se rates were measured with a portable scintillation counter, but in t he Ljubljana region thermoluminescence dosimeters were also exposed. T he results ranged from 30 to 295 nGy h(-1), with a geometric mean of 8 8 nGy h(-1).