Estimation of environmental radioactivity and radiation dose from exposure to radon in groundwater for inhabitants in Qassim Area, Saudi Arabia

Studies of radon isotope 222Rn activity concentration in underground water used for irrigation and consumption in Al-Asyah city-Saudi Arabia were performed using RAD7 electronic radon identifier associated with RAD-H2O extra (Durridge Co., USA). Waters samples chosen for investigations were gathered from 18 various wells in and around the town. The activity concentration of 222Rn varied from 1.2 ± 0.3 to 12.6 ± 1.6 Bq L–1, with an average of 5.1 ± 1.1 Bq L–1. The annual effective dose per liter was calculated for inhabitants to be in the range 6.0 ± 1.4 to 62.9 ± 8.2 nSv L–1 with a mean value of 25.4 ± 5.4 nSv L–1. The annual effective doses rate for ingestion and inhalation due to the consumption of 222Rn with water ranged from 4.4 ± 1.1 to 45.9 ± 5.9 μSv y–1, with an average of 18.5 ± 3.9 μSv y–1 and from 3.0 ± 0.7 to 31.7 ± 4.1 μSv y–1, with an average of 12.8 ± 2.7 μSv y–1, respectively. The total annual effective dose ranged from 7.4 ± 1.7 to 77.6 ± 10.1 μSv y–1, with an average of 31.3 ± 6.6 μSv y–1. Moreover, roughly 11% of our samples were above the maximum contamination level, while 89% from the samples are below the maximum contaminant level as quoted by US Environmental Protection Agency. The results showed that radon from water would be expected to contribute by (5.1 ± 1.1) × 10–4 Bq L–1 to the indoor air radon concentration. The results were compared with other results.