Radon is a dense, radioactive chemical element that exists mainly as a noble gas with the symbol Rn on the periodic table and atomic number 86. It is invisible, colorless, and odorless. Radon gas often accumulates in low-lying areas, such as basements, and exists in many homes and some workplaces and exists undetected by the building’s occupants. Radon gas has been identified as a carcinogen meaning it has been linked as a cause of lung cancer across the country.