Indoor exposure to radon: What are the health effects in non-occupational environments?

Radon is the largest single source of ionizing radiation to which humans are exposed. Epidemiological studies of uranium miners and experimental animals indicate that radon can cause lung cancer. Radon is ubiquitous and can accumulate indoors as a result of inadequate ventilation. Indoor radon levels are considerably lower than those occurring in mines, and consequently the health risks of exposure to low-level radiation is difficult to assess. Epidemiological studies suggest that, at the levels typically encountered by the general public, there is no convincing evidence that elevated radon levels cause an increase in the number of lung cancers. The magnitude of the exposure of the South African population to radon is unknown. This paper endeavours to put the need for epidemiological studies on radon-related risk in perspective.