Indoor radon and ambient gamma radiation in an educational building: dynamics and dose assessment

The spatial distribution and short-term variability of indoor radon activity concentration and ambient gamma dose equivalent H*(10) were investigated in a multi-level educational building. Radon activity concentration was measured using CR-39 detectors and active AlphaGUARD monitoring, while ambient gamma dose was determined with thermoluminescent dosimeters (TLD). Radon activity concentrations followed a log-normal distribution with an annual geometric mean of 32.20 Bq/m³ and GSD = 3.16. Marked spatial variability was observed, particularly at ground-floor level. The estimated effective doses were 0.41 mSv/y from radon and 0.26 mSv/y from ambient gamma radiation.