Radon is a the #1 cause of lung cancer for non smokers. It is a naturally occurring, radioactive, odorless, tasteless, invisible gas that is produced by decaying uranium. It becomes a threat when it gets trapped in buildings.
Buyers can get a radon test during the inspection contingency and negotiate with the sellers if there are high radon levels.
Find more information, visit the EPA website on Radon at www.epa.gov/radon