Pennsylvania consistently ranks among the highest-radon states in the U.S., with an estimated average indoor radon level around 6.0 pCi/L statewide. The Pennsylvania Department of Environmental Protection estimates that approximately 40% of Pennsylvania homes have radon levels above the EPA action level. Pennsylvania’s geology — including Reading Prong granite, black shale, and carbonate rock formations — creates particularly high radon potential in the southeastern and south-central regions of the state.
EPA Radon Zone Designation
Pennsylvania is predominantly EPA Radon Zone 1. The majority of Pennsylvania counties are Zone 1, with particularly high radon potential in counties overlying the Reading Prong geological formation in the southeast (Bucks, Chester, Montgomery, Berks, Lehigh, Northampton counties) and limestone/carbonate geology in the south-central region (Adams, Cumberland, Franklin, York, Lancaster counties). Some northern and western counties are Zone 2.
Radon Contractor Licensing in Pennsylvania
Pennsylvania has a comprehensive radon contractor licensing program administered by the Pennsylvania Department of Environmental Protection. Radon measurement and mitigation contractors must hold a Pennsylvania state license to legally perform radon services in the state. Pennsylvania licensing requires passing state examinations (or demonstrating NRPP/NRSB certification), carrying liability insurance, and completing continuing education. The DEP maintains an online searchable database of licensed radon professionals at dep.pa.gov. Performing radon work without a Pennsylvania license is illegal and a violation of the Radon Certification Act.
Radon Disclosure Requirements in Pennsylvania
Pennsylvania has specific radon disclosure requirements under its real estate disclosure law. Sellers must complete the Seller’s Property Disclosure Statement, which includes questions about radon — specifically whether the property has been tested and what the results were, and whether a radon mitigation system is present. Pennsylvania does not require sellers to test before selling, but known results must be disclosed. Given Pennsylvania’s high radon prevalence, radon contingencies are standard in Pennsylvania real estate transactions, and buyers routinely request independent testing.
Radon-Resistant New Construction (RRNC) in Pennsylvania
Pennsylvania does not have a statewide mandate requiring RRNC for all new construction, but the Pennsylvania DEP strongly recommends RRNC for new homes — particularly in Zone 1 counties. Some municipalities within Pennsylvania have adopted local RRNC requirements. The IRC Appendix F RRNC provisions are available for local adoption. Buyers of new construction in Pennsylvania should ask their builder directly whether RRNC features are included, particularly in the high-radon southeastern and south-central counties.
Highest-Radon Counties and Areas in Pennsylvania
Pennsylvania’s highest-radon areas include counties overlying the Reading Prong geological formation: Bucks, Chester, Montgomery, Berks, Lehigh, and Northampton in the southeast. South-central counties including Adams, York, Lancaster, Cumberland, and Franklin — which overlie limestone and carbonate geology — also show high average radon levels. The PA DEP’s county-level radon data is available on their website and shows average indoor radon measurements for each county based on test results submitted to the program.
Testing Resources for Pennsylvania Residents
The Pennsylvania Department of Environmental Protection administers the state radon program and provides resources for homeowners including lists of certified contractors, low-cost or free test kit programs (availability varies by year and funding), and technical guidance on radon mitigation. Contact the state radon program directly for the most current contractor list, any available test kit distribution programs, and jurisdiction-specific requirements that may have changed since this page was last updated.
Frequently Asked Questions
Does Pennsylvania require radon contractor licensing?
Yes. Pennsylvania has a comprehensive Radon Certification Act requiring contractors to hold a state license for radon measurement and mitigation work. Verify license status through the Pennsylvania DEP radon program before hiring any contractor.
What parts of Pennsylvania have the highest radon levels?
The Reading Prong geological formation in southeastern Pennsylvania (Bucks, Chester, Montgomery, Berks, Lehigh, Northampton counties) has some of the nation’s highest radon concentrations. South-central counties including Adams, York, Lancaster, Cumberland, and Franklin also show elevated average radon levels.
Is radon testing required when buying a house in Pennsylvania?
Not legally required, but strongly recommended and standard practice. Pennsylvania sellers must disclose known radon test results, but they are not required to test before selling. Buyers should always conduct independent testing during the inspection contingency period.
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