Radon gas is colorless, odorless and a radioactive by-product of uranium. Radon is found in almost every state and may effect over ten million American homes. Any home can be effected, however radon gas tends to be in higher concentrations in homes that are tightly sealed up. A more drafty house is likely to have a less of a concentration of radon gas.
The issue with radon is that is decays or breaks down into radon daughters. The radon daughters can attach to dust particles and then can be inhaled. There have been studies that indicate a significantly increased risk of lung cancer in high radon homes then lower. The risk is even greater if a person is a smoker.
Radon enters a home through cracks in basement floors, cracks in foundations, dirt floors, unsealed penetrations, sump pump pits, foundation drains and rock foundations. It is very prudent to have a home tested for radon gas before you purchase it.