Radionuclide Basics: Radon
Radon (chemical symbol Rn) is an odorless, colorless, radioactive gas. It is the leading cause of lung cancer for U.S. residents who have never smoked.
Half-lifeThe time required for half of the radioactive atoms present to decay or transform. Some radionuclides have half-lives of mere seconds, but others have half-lives of hundreds or millions of years.
Radon is a radioactive gas. It comes from the natural decay of uranium and radium found in nearly all rocks and soils. Elevated radon levels have been found in every state. Radon is in the atmosphere and can also be found in ground water. The national average for radon in outdoor air is 0.4 picocuries per liter (pCi/L), while the average for indoor air is 1.3 pCi/L.
Radon can move up from the ground into buildings through openings in floors or walls that are in contact with the ground. Radon can accumulate in buildings and, over time, can pose a serious health hazard. Learn more about radon.
