Radon is a radioactive gas that emanates from rocks and soils and tends to concentrate in enclosed spaces, such as underground mines or houses. Soil gas infiltration is recognized as the most important source of residential radon. Other sources, including building materials and water extracted from wells, are less important in most circumstances. Radon is a major contributor to the ionizing radiation dose received by the general population.
Epidemiological studies have shown a clear link between breathing high concentrations of Radon and incidence of lung cancer. Radon is a contaminant that affects indoor air quality worldwide. According to the United States Environmental Protection Agency, Radon is the second most frequent cause of lung cancer, after cigarette smoking, causing 21,000 lung cancer deaths per year in the United States. About 2,900 of these deaths occur among people who have never smoked. While Radon is the second most frequent cause of lung cancer, it is the number one cause among non-smokers, according to EPA estimates. As Radon itself decays, it produces decay products, which are other radioactive elements called Radon daughters (also known as Radon progeny). Unlike the gaseous Radon itself, Radon daughters are solids and stick to surfaces, such as dust particles in the air. If such contaminated dust is inhaled, these particles can also cause lung cancer.
Radon measurements are relatively simple to perform and essential to assess Radon concentration in homes. Indoor Radon concentration varies with the construction of buildings and ventilation habits.
Short-term measurements provide only a crude indication of the actual Radon concentration.
More useful information can be found in the ‘Home buyer’s and seller’s guide to radon’ by EPA.