Assessment of lung cancer risk due to exposure to radon from coastal sediments.

We conducted a lung cancer risk assessment for internal exposure to naturally occurring 222Rn gas both indoor and outdoor. A series of equations were used to estimate Rn concentrations indoor and outdoor and the associated lung cancer risk in some coastal regions in Egypt. The mean 222Rn concentrations were 42.98 (SD 33.12) Bq/m3 and 8.63 (SD 6.16) Bq/m3 indoor and outdoor respectively. The mean risk of radon-induced cancer (deaths per million population) was 83.4 (SD 64.67) indoors and 25.1 (SD19.52) outdoors. Levels were higher for western regions of the country compared to eastern ones but the highest levels were in Rashid (Nile delta). Smoking was shown to increase the risk considerably.