Abstract
The annual effective radon doses for residents of 92 dwellings in Jazan city located in Northern Saudi Arabia are calculated from the radon concentration and equilibrium factor F, measured using passive technique. The overall average (+/- 1 SD) of radon concentration, equilibrium factor and annual effective dose are 118 +/- 12 Bq m(-3), 0.3 +/- 0.02 and 2.32 +/- 0.17 mSv, respectively. Although 93% of the dwellings have radon concentrations below the reference level, about 24% of the dwellings have annual effective radon doses within the range of recommended action level of 3-10 mSv. The exhalation rate of radon from different environmental samples was measured and used in theoretical calculations to estimate the annual effective dose of radon at different conditions of ventilation and dwelling size. The correlation between the experimental measurements and theoretical estimation of radon doses is good at high ventilation rate (low F) and shows some deviation at low ventilation rate (high F). The theory gives lower radon doses than those measured especially at low ventilation and is likely attributed to the influence of building design and the variety of living style at the homes.