Soil radioactivity levels and associated hazards in selected towns in uranium-rich western Namibia

Abstract

Soil samples from three major towns and a holiday settlement in uranium-rich western Namibia have been analysed using a HPGe detector for radioactivity due to 238U, 232Th and 40K. The average activity concentrations of the radionuclides in the towns and settlement vary from a low of 18.6 ± 4.6 to a high of 69.6 ± 26.3 Bq kg−1 for 238U, 23.8 ± 8.4 to 91.1 ± 41.0 Bq kg−1 for 232Th and 460.3 ± 76.2 to 959.5 ± 194.7 Bq kg−1 for 40K. In order to evaluate the associated health hazard, the concentrations were used to calculate the mean annual effective dose, radium equivalent activity (Raeq) and external hazard index (Hex) for the towns and settlement. The values of 0.11 mSv, 195.3 Bq kg−1 and 0.53 obtained respectively for the mean annual effective dose, Raeq and Hex are, however, below their permissible limits thus implying that radiation hazard is negligible.