It all started in the 1980’s with a nuclear power plant employee that was setting off the radioactive alarms on his way IN to work. After a lengthy investigation, they found the source of his radioactive contamination was the Radon gas in his home. From there the EPA began various studies to determine its significance in the home and the best techniques to reduce the amount of radon that accumulates in the home
Read more here: http://articles.chicagotribune.com/1987-10-08/news/8703160117_1_stanley-watras-radon-hot-spots-reading-prong