Assessment of γ–radiation levels and associated dose rates from surface soils in the eastern part of Botswana

This paper reports the γ–radiation levels of the naturally occurring 40K, 210Pb, 232Th and 226Ra and the anthropogenic 137Cs in the eastern part of Botswana so as to assess their possible dose impact to the members of the public in the area. The radium equivalent activity was (175±24) Bq/kg, and thus below the allowed maximum value of 370 Bq/kg. The total absorbed rate ranged from 24.12 nGy/h to 215.44 nGy/h with the mean of (81.36±10.58) nGy/h. The outdoor annual effective dose ranged from 0.030 mSv/y to 0.264 mSv/y with an average value of (0.10±0.01) mSv/y. The obtained values are comparable with world–wide averages. Results from this study can be used to serve as baseline data for the study area, which can also be used as reference information to assess any changes in radioactivity background possibly due to the artificial influences.