Review : Radon as an Indoor Air Hazard

The radioactive gas radon-222 is the immediate daughter of radium-226, which is present in soils, rocks and building materials. The gas decays into radioactive daughters, which irradiate cells in the respiratory tract. It is the radiation dose to these cells that causes the risk of subsequent lung cancer. Radon-induced lung cancer is well established as an occupational disease in several forms of mining, notably uranium mining where the data are sufficient to provide a quantitative relationship between exposure and the excess risk of cancer. The concentration in dwellings is usually much lower than in mines, and epidemiological studies have produced conflicting results. Current views on the magnitude of the risk from radon in indoor air are presented, with an account of the actions recommended to limit the risk.