Abstract
The activity levels of Ra-226, Th-232, and K-40 in 38 soil samples collected from four areas (Al Assyah, Buraidah, Al Shamassea, and Al Badayyia) in Qassim (Saudi Arabia) were determined by gamma-ray spectrometry with a NaI(Tl) detector. The activity concentrations of Ra-226, Th-232, and K-40 varied from 9.6 +/- 0.2 to 158.6 +/- 0.1, from 9.6 +/- 0.1 to 110.0 +/- 0.4, and from 70.1 +/- 0.5 to 390.3 +/- 1.5 Bq/kg, respectively. Also, the annual effective dose rate was estimated to assess the health hazards caused by the external exposure to people living in these regions. The concentrations of K-40 and Th-232 are lower than the world average, whereas the Ra-226 concentration is higher than the recommended level detailed by UNSCEAR.