Radon FAQ: Pennsylvania
Common questions about radon testing, mitigation, costs, and Pennsylvania regulations — answered for homeowners across the Commonwealth.
What is radon?
Radon is a naturally occurring radioactive gas produced by the decay of uranium in soil and rock. It is colorless, odorless, and tasteless — undetectable without a test. Radon seeps into buildings through foundation cracks, gaps around pipes, and other openings. Long-term exposure is the second leading cause of lung cancer in the United States, responsible for approximately 21,000 deaths per year according to the EPA.
What is the EPA action level for radon?
The EPA recommends mitigation when radon levels reach or exceed 4.0 picocuries per liter (pCi/L) of air. The EPA also suggests considering mitigation for levels between 2.0 and 4.0 pCi/L. The average indoor radon level in the U.S. is 1.3 pCi/L; the average outdoor level is 0.4 pCi/L. Pennsylvania has one of the highest radon exposure rates in the country — approximately 40% of PA homes exceed the 4.0 pCi/L threshold.
What is Pennsylvania Senate Bill 760?
Pennsylvania Senate Bill 760 (SB 760), signed into law in 2024, requires radon testing in public school buildings constructed before 2014 in EPA Zone 1 counties — the highest-risk classification. Initial testing must be completed during the 2026–2027 academic year. Buildings that test at or above 4.0 pCi/L must be mitigated within six months of confirmatory testing. Results must be publicly reported to the school board, parents, and PA DEP. SB 760 does not require homeowners to test their properties.
How much does radon mitigation cost in Pennsylvania?
Most Pennsylvania homeowners pay between $800 and $2,500 for a sub-slab depressurization (ASD) system — the most common and effective mitigation method. Basic installations in new construction or accessible slabs typically run $800–$1,200. Complex systems involving stone foundations, multiple suction points, or finished basements typically cost $1,500–$2,500+. Testing adds $125–$300 for a short-term test and $200–$400 for a long-term test.
How long does radon mitigation take?
Most residential sub-slab depressurization installations take 4–8 hours. After installation, the system operates continuously. A post-mitigation test (typically a 48-hour short-term charcoal test) should be performed 24–48 hours after installation to confirm levels have dropped below 4.0 pCi/L. Most systems reduce radon levels by 90% or more.
How do I find a DEP-certified radon contractor in Pennsylvania?
Pennsylvania requires all radon testing and mitigation professionals to hold active certifications from the PA Department of Environmental Protection (DEP) under the Radon Certification Act (Act 43 of 1987). You can verify any contractor's certification status through the PA DEP Bureau of Radiation Protection. Our Find Pros directory lists DEP-certified professionals organized by region and city.
Do I need to test my home after mitigation?
Yes. A post-mitigation test is strongly recommended — and required by ANSI-AARST standards (CCAH) — to confirm the system is working. The test should be performed 24–48 hours after installation with all windows and doors closed (closed-house conditions). Most DEP-certified contractors will either perform this test or provide a test kit. If the post-mitigation result is still at or above 4.0 pCi/L, additional suction points or system adjustments are needed. Annual or biennial retesting is recommended to ensure ongoing performance.
Is radon testing required when selling a home in Pennsylvania?
Pennsylvania does not require sellers to conduct a radon test before selling. However, PA Code § 7304 requires sellers to disclose any known radon test results to buyers in a real estate transaction. In practice, most PA real estate contracts include a radon contingency — buyers commonly request testing as part of the home inspection process, and sellers with elevated results are often expected to mitigate or negotiate a price reduction.
What is a sub-slab depressurization (ASD) system?
Active sub-slab depressurization (ASD) is the most common and effective radon mitigation method. A contractor drills one or more holes through the basement slab or foundation floor, inserts a PVC pipe, and connects it to a continuously running fan. The fan creates negative pressure beneath the slab, drawing radon-laden soil gas out before it can enter the living space and exhausting it above the roofline. ANSI-AARST CCAH standards govern residential ASD installations in Pennsylvania.
What EPA radon zones apply to Pennsylvania?
Pennsylvania counties are classified into EPA Zones 1, 2, and 3 based on predicted radon potential. Zone 1 (highest risk) covers much of south-central and southeastern Pennsylvania — including counties in the Reading Prong granite formation and Appalachian ridge areas. Zone 2 (moderate risk) covers much of central and northeastern PA. Zone 3 (lower risk) includes parts of the Philadelphia metro. However, zone classifications are county-level averages — radon levels can vary significantly block by block based on local geology, soil permeability, and building construction.
Related Resources
PA Radon Hub is an independent informational resource. We do not perform radon testing or mitigation. Content on this page is for general information only and does not constitute professional advice. Always consult a DEP-certified radon professional for your specific situation.