Furthermore, we assessed gamma ray radiation external hazard indexes and
annual effective dose rate from the natural radioactivity elements (226Ra, 232Th and 40K) levels in the
surface soils of the study area. The highest average values for the specific activity of 232Th (31 Bq kg1),
40K (615 Bq kg 1), and 226Ra (25 Bq kg1) are lower than limit recommended by OECD, so no significant
radioactive risk was detected within the study area. In addition, no significant variability of radioactive
risk was observed among sampling locations.