Radon Pros in Pennsylvania

Last updated: March 2026

Pennsylvania has one of the most severe radon problems in the United States and holds a unique place in radon history — the national awareness of residential radon began in Pennsylvania in 1984 when Stanley Watras, a construction worker at the Limerick nuclear power plant, set off radiation alarms due to radon exposure at his Boyertown home. The Reading Prong geological formation runs through eastern Pennsylvania, producing extremely high indoor radon levels in the Lehigh Valley, Berks County, and surrounding areas. Parts of the Poconos routinely test above 20 pCi/L — five times the EPA action level. Eastern and central Pennsylvania are heavily Zone 1, while western Pennsylvania has a mix of Zone 1 and Zone 2 areas. Pennsylvania requires all radon testers and mitigators to be certified by the PA DEP, and the state maintains a public list of certified professionals. In real estate transactions, PA law requires real estate professionals to provide radon information to buyers, and in practice testing is nearly universal in eastern PA transactions. Pennsylvania's combination of extreme geological risk, strong regulatory oversight, and historical significance makes it one of the most radon-aware states in the country. The PA DEP recommends all homes be tested, with particular urgency in the eastern counties along the Reading Prong.