What is radon?
Radon is a radioactive gas that has no smell, colour or taste. Radon is produced from the natural radioactive decay of uranium, which is found in all rocks and soils. Radon can also be found in water.
Radon escapes from the ground into the air, where it decays and produces further radioactive particles. As we breathe, these particles are deposited on the cells lining the airways, where they can damage DNA and potentially cause lung cancer.
Outdoors, radon quickly dilutes to very low concentrations and is generally not a problem. The average outdoor radon level1 varies from 5 Bq/m3 to 15 Bq/m3. However, radon concentrations are higher indoors and in areas with minimal ventilation, with highest levels found in places like mines, caves and water treatment facilities. In buildings such as homes, schools, offices, radon levels can vary substantially from 10 Bq/m3 to more than 10 000 Bq/m3. Given the properties of radon, occupants of such buildings could unknowingly be living or working in very high radon levels.
Health effects of radon
Radon is a major cause of lung cancer. It is estimated that radon causes between 3% to 14% of all lung cancers in a country, depending on the national average radon level and the smoking prevalence.
An increased rate of lung cancer was first seen in uranium miners exposed to very high concentrations of radon. In addition, studies in Europe, North America and China have confirmed that even low concentrations of radon – such as those commonly found in residential settings – also pose health risks and contribute to the occurrence of lung cancers worldwide.
The risk of lung cancer increases by about 16% per 100 Bq/m3 increase in long time average radon concentration. The dose-response relation is assumed to be linear – i.e. the risk of lung cancer increases proportionally with increasing radon exposure.
Radon is much more likely to cause lung cancer in people who smoke. In fact, smokers are estimated to be 25 times more at risk from radon than non-smokers. No other cancer risks or other health effects have been established to date, although inhaled radon can deliver radiation to other organs, but at a much lower level than to the lungs.