A combination study of indoor radon and in situ gamma spectrometry measurements in Greek dwellings

The aim of the present study was to investigate a possible correlation between indoor radon and indoor gamma dose rates deduced by in situ gamma spectrometry measurements by using a portable HPGe detector. Indoor radon and high resolution in situ gamma spectrometry measurements were performed in 60 apartments in Thessaloniki, the second largest city of Greece. Geometric mean radon concentration is 52 Bq m-3. The mean total absorbed dose rate in air due to gamma radiation is 56 ± 9 nGy h-1. The contribution of the different radionuclides to the total indoor gamma dose rate in air is 41% due to 40K, 36% due to the thorium series and 23% due to the uranium series. No correlation was found between indoor gamma dose rate due to the uranium series and indoor radon for ground and first floor apartments. For upper floor apartments (above second floor) a weak correlation is observed. The mean annual effective dose due to radon is 1.15 mSv, i.e. more than four times higher compared to the effective dose due to gamma radiation (0.27 mSv). (author)