Evaluation of radon hazards at the rural settlements of Uzbekistan.

Abstract

The "passive" sorption detectors based on the activated charcoal together with scintillation spectrometry were utilized to measure radon flux density from the soil surface as well as volumetric activity of indoor radon at the dwellings of rural areas of Uzbekistan. Additionally, gamma dose rates as well as concentrations of natural radionuclides in soil and building materials samples were determined. Based on the values of natural radionuclides, common radiological indices have been calculated. It was found that varying greatly, 94% radon flux density values did not exceed 80mBq/(m2·s), while volumetric activities of radon were in the range of 35-564Bq/m3. The radium equivalent activity for studied soil and building materials samples were below the allowed limit of 370Bq/kg. Computed gamma dose rates were in the range of 55.50-73.89 ƞGyh-1 below the limit of 80 ƞGyh-1 and annual effective dose rate 0.068-0.091 mSvy-1, the average value of which was higher than the standard limit > 0.47 mSvy-1. The gamma representative index range was 0.89-1.19 with an average of 1.002 which was higher than the standard limit of 1.0. The range of activity utilization index was equal to 0.70-0.86 with an average value 0.77 which was lower than the recommended level ≤ 2.0. And lastly, excess lifetime cancer risk index values were from 1.9 × 10-4 to 2.5 × 10-4 and were lower than the recommended value 2.9 × 10-4 indicating low radiological risk. The results are consistent with the research conducted by other authors earlier, implying suitability of employing the method for the assessment of residential areas.