Abstract
Internal exposure from inhalation of radon and its progeny is one of the most significant sources of natural radiation exposure of the population. Radon levels and radon equilibrium factor were measured in the dwellings of Al-Kharj, Saudi Arabia using passive technique. Calibrated CR-39 diffusion type radon detectors were used for radon measurements and the method of can and bare is adapted for the measurement of radon equilibrium factor. Passive measurements enable the accumulation of the result over a long period and cover a wide area. The probability of cancer induction and then the expected mortality was calculated based on different approaches. The results show that the overall weighted mean of annual effective dose for Al-Kharj resident is equal to 1.51 ± 0.8 mSv and The average expected mortality for residents in dwellings of Al-Kharj city is ranged from 0.596 ± 0.25 to 0.369 ± 0.15 death per 10,000 persons of ages from 40 to 70 years respectively. Also, the lifetime excess absolute risk (LEAR) of the residents of the Al-Kharj city is equal to (2.06 ± 0.8) × 10−4. The effect of dwelling types, ventilation and construction materials on the expected mortality is discussed. Keywords: KSA dwellings, Radon levels, CR-39, Expected mortality, Fatality risk