Radon is a radioactive gas that has been found in homes, schools and other buildings around the world. Radon comes from the natural breakdown of uranium in soil and rock, and moves up into the indoor air that people breathe. Radon is the leading cause of lung cancer in non-smokers. Radon mitigation systems reduce radon levels in homes and buildings. Inspection of these systems helps assure that they were installed properly and are performing as designed.