Radon is a radioactive gas made by the natural breakdown of uranium, which is found at higher than normal levels in the soil in some parts of the US. Radon can't be seen, tasted, or smelled. Radon can become concentrated indoors and create a possible risk for cancer. Smokers are especially sensitive to the effects of radon. State and local offices of the EPA (Environmental Protection Agency) can provide information about how to test for radon in the home.