2026-05-11 · 4 min read
Radon Mitigation in Allentown, PA: Lehigh Valley Sits on the Reading Prong
Allentown and the Lehigh Valley sit directly on the Reading Prong — one of the most uranium-rich geological formations in the eastern US. Radon is extremely common here.
Ground Zero for Eastern US Radon
The Reading Prong is arguably the most significant radon geology in the eastern United States. This northeast-trending band of Precambrian metamorphic and granitic rock — rich in uranium, thorium, and radium — extends from Reading, PA through the Lehigh Valley (Allentown, Bethlehem, Easton) and into New Jersey and Connecticut.
Allentown and Lehigh County sit at or near the core of this formation. Uranium concentrations in the Reading Prong gneiss and granites are 3–8 times higher than average crustal rock. The radon generated from this uranium enters homes through soil, fractured rock, and foundation gaps at rates far exceeding national averages.
Pennsylvania's statewide average indoor radon (7+ pCi/L) is substantially driven by the Reading Prong zone. Lehigh Valley testing surveys routinely show median indoor radon levels of 8–15 pCi/L — well above the national average of 1.3 pCi/L.
What 20+ pCi/L Homes Need
Many Allentown-area homes that haven't been mitigated test in the 15–40 pCi/L range. At these levels, standard single-suction-point installations with an XP201 fan may not achieve the EPA target of below 4.0 pCi/L. A proper installation for a high-radon Allentown home typically involves:
- Sub-slab communication test: Confirming pressure field extension before finalizing suction point locations
- Higher-suction fan: GX3 or GX5 for homes above 15 pCi/L or with difficult sub-slab material
- Multiple suction points: If the home footprint is large or sub-slab material restricts pressure extension
- Foundation sealing: Caulking visible cracks, sealing the floor-wall joint, and covering open sump pits before energizing the system
Post-mitigation testing is especially important in Allentown. After installation, confirm with a 30-day test that levels have dropped below 2.0 pCi/L, not just below 4.0 pCi/L.
The PA DEP Requirement
Pennsylvania's mandatory PA DEP Radon Contractor licensure is the operative credential in the Lehigh Valley. Any contractor performing mitigation work in Pennsylvania must hold a valid PA DEP license. Verify before hiring — the PA DEP directory is searchable online.
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Frequently Asked Questions
Why is radon so high in Allentown?
Allentown and Lehigh County sit directly on the Reading Prong — a northeast-trending ridge of Precambrian metamorphic and granitic rock with exceptionally high uranium content. This formation is the source of the highest residential radon readings in the eastern US. Many Allentown-area homes test 15–40 pCi/L or higher.
How much does radon mitigation cost in Allentown?
Allentown homeowners typically pay $1,000–$2,200 for standard sub-slab depressurization. High pre-mitigation levels (often 15–40 pCi/L) sometimes require a higher-suction GX3 or GX5 fan and potentially multiple suction points, pushing costs higher than in lower-radon areas.
Does Pennsylvania require special licensing for radon contractors in Allentown?
Yes — PA DEP Radon Contractor licensure is required for all radon mitigators in Pennsylvania. Verify PA DEP licensure, not just NRPP certification. The PA DEP licensing requirement is specific to Pennsylvania.
Find a Certified Mitigator Near You
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