A colorless, odorless, naturally occurring gas produced from the decay of natural radioactive minerals in the ground. Radon is a carcinogen responsible for thousands of lung cancer deaths each year. Presence in a building is measured as picocuries per liter of air (pCi?L). The EPA suggested action level is 4, and levels above this have been found in homes and buildings in most every state and territory.
Levels build up when radon is drawn into a building by exhaust systems and fans and thermal stack effects through cracks in a basement drain. A 48-hour test is recommended during a real estate transaction. Mitigation consists of sealing cracks, installing PVC pipe into the ground that exits the building through the highest level. A small fan will draw the ground air and radon through the pipe and into outdoor air where the radon will dissipate. In most states, brokers must disclose known radon problems and the presence of mitigation systems.