Radon is a radioactive gas that seeps into houses from decaying granite and slate underground. As the radon gas rises, it enters houses through cracks in the basement and sump pump wells. Once the radon enters the basement of a house, it begins to accumulate in the low areas. Because radon is heavier than air, and basements are often not ventilated well, radon gas can reach dangerous levels quickly. High radon levels are the second leading cause of lung cancer and is attributed to over 20,000 deaths in the United States alone. Radon can be found in all areas of the world and is undetectable to human senses.
The European Union and Canadian governments recommend that houses have less than 4 pCi/L (picocuries per liter, a measure of radiation) while the US Environmental Protection Agency recommends radon levels of no more than 4 pCi/L and says that even a radon level of 2pCi/L can be very dangerous. You can measure your radon levels by purchasing a radon detector and hanging it in your basement. After leaving it for a few days, package the detector and mail it to a radon laboratory where it can be analyzed. If the Radon test is positive you should then purchase a longer term (up to 1 year) test to confirm the presence of Radon and to pinpoint how much of the radioactive gas is present.
There are two main methods to lower the concentration of radon in your home. The first is to prevent radon from entering your home in the first place. This can be accomplished by using a foam sealant to fill any cracks in your basement floor and walls which might allow radon to enter. The second is to install a ventilation system remove the contaminated air and blow it harmlessly outside.