Radon Mitigation in Allentown
Allentown sits at the geographic core of the Reading Prong in Lehigh County — the single highest-risk metropolitan area in Pennsylvania for residential radon exposure. The city's position on high-uranium granite and gneiss, combined with its dense pre-1960 housing stock and basement-dominant construction, produces indoor radon concentrations that frequently exceed the EPA action level by a factor of two or more. Lehigh County's radon problem is geological and permanent: the uranium decay chain operates continuously regardless of season or weather. Adjacent Northampton County — home to Bethlehem and Easton — shares the same Reading Prong geology and risk profile. Active sub-slab depressurization (ASD) using systems such as the RadonAway RP145 is the standard mitigation approach for Lehigh County foundations.
High Radon Risk Area
Allentown sits in EPA Zone 1 — testing is recommended for every home regardless of age or foundation type.
Local Geology & Risk Factors
Allentown is located in an area with Reading Prong / Limestone-Dolomite Karst geology, which contributes to elevated radon levels. The Pennsylvania DEP identifies this region as having significant radon potential due to uranium-bearing rock formations.
Testing is essential because radon levels can vary significantly between neighboring homes based on construction, soil permeability, and ventilation.
See Pennsylvania radon levels and EPA radon zone classifications →
The northern portions of Allentown and the adjacent townships sit closest to the Reading Prong geological contact. Soils here are a mix of Reading Prong-derived residuum and carbonate residuum, with fracture-connected bedrock close to the surface. This zone produces the highest individual home radon readings in the Lehigh Valley — concentrations comparable to the Reading Prong core in Berks County. Older homes in North Allentown (pre-1950) with block or stone foundations are the highest-risk category. The combination of uranium-rich soils, shallow fractured bedrock, and highly permeable older foundations creates maximum radon entry conditions.
Quick Facts
- Median home value: $188,900 · Median year built: 1951
- Population: 125,320
- Foundation types: Basement (most common); Crawlspace (limestone areas); Slab-on-grade (newer construction)
Lehigh County Context
Allentown is a municipality of Lehigh County, EPA Zone 1. Zone designation is assigned at the county level, so Allentown inherits its classification; countywide aggregate figures live on the county page.
See Lehigh County radon aggregate data →Measured Radon Data for Allentown
This unusually high reading may reflect a source data anomaly or a single-home outlier; individual home results vary widely.
Source: PA DEP RadonZip Tool, January 1990 – December 2025 · Updated 2026-05-20
Radon Mitigation Cost in Allentown
Active sub-slab depressurization (ASD) systems in Allentown typically cost $1,000–$2,500. Standard basement installs on modern poured concrete fall at the lower end; historic foundations, block-wall depressurization, multi-point suction, and crawlspace encapsulation push costs higher.
Foundations covered locally
- Basement (most common)
- Crawlspace (limestone areas)
- Slab-on-grade (newer construction)
Systems used in the region
- Active sub-slab depressurization
- Crawlspace encapsulation
- Multi-point suction systems
Certification & Compliance
All Pennsylvania radon testing and mitigation professionals must hold active PA DEP certification. Ask any contractor for their certification number and verify it before signing.
Pennsylvania's Real Estate Seller Disclosure Law (68 Pa.C.S. §§ 7301–7315) requires sellers to disclose known material defects to buyers under § 7303; the mandated disclosure form records radon under § 7304(b)(14). Sellers who have never tested are not compelled to test — § 7308 imposes no affirmative duty to investigate — but pre-listing testing is standard practice across most PA markets.
Under 25 Pa. Code § 240 — the Pennsylvania chapter governing radon certification — every radon service provider working in the Commonwealth must hold current DEP certification. Verify the contractor's status via the DEP Radon Services Directory before hiring.
Verify Contractor Certification — PA DEP Official Directory for Allentown, Lehigh County
View PA DEP Certified Contractor DirectoryThe PA Department of Environmental Protection maintains the official list of certified radon testers and mitigators, sorted by county and updated monthly. Always verify certification before hiring any contractor.
Directory resource provided by PA DEP Bureau of Radiation Protection, Radon Division.
Frequently Asked Questions
How does Lehigh Valley limestone geology affect radon levels in Allentown?
The limestone and dolomite bedrock beneath Allentown creates natural underground void networks. These karst channels allow radon gas to migrate rapidly from soil into homes through crawlspaces and foundation cracks. Even neighboring homes can have vastly different radon levels depending on proximity to these subsurface channels.
What radon mitigation systems are used in Allentown homes?
Most Allentown installations use active sub-slab depressurization (ASD). Limestone karst areas may require multi-point suction systems to address multiple soil gas entry points. Crawlspace encapsulation is common in older properties with exposed dirt floors. DEP-certified contractors assess each home individually.
What does radon mitigation cost in Allentown?
Standard ASD systems in Allentown cost $1,000–$2,500 depending on foundation type, home size, and system complexity. Homes with karst limestone foundations may require additional suction points, increasing costs. Obtain quotes from at least three DEP-certified contractors.
What's the average radon level in Allentown?
Allentown's DEP-recorded basement average is 6.67 pCi/L across 20,720 tests. The EPA action level for mitigation is 4.0 pCi/L, so a sizable share of Allentown homes exceed the threshold. The highest single result in the local dataset is 569.9 pCi/L; this unusually high reading may reflect a source data anomaly or a single-home outlier — individual home results vary widely.
Do homes in Allentown need to be tested for radon?
Lehigh County is EPA Zone 1 — the highest radon-potential classification — so every home in Allentown should be tested regardless of age, foundation type, or neighborhood. Short-term charcoal or continuous monitor tests take 48–96 hours and cost $15–$50; long-term alpha-track tests run 90 days and better represent annual averages. If the result meets or exceeds 4.0 pCi/L, mitigation by a DEP-certified professional is recommended.
How much does radon mitigation cost in Allentown?
Active sub-slab depressurization (ASD) systems in the Allentown area typically cost $1,000–$2,500. Standard basement installations on modern poured-concrete foundations fall at the lower end; historic foundations, block-wall depressurization, multi-point suction, and crawlspace encapsulation push costs toward the upper end. All work must be performed by a DEP-certified mitigation professional under 25 Pa. Code § 240.
Is radon disclosure required when selling a home in Allentown?
Pennsylvania's Real Estate Seller Disclosure Law (68 Pa.C.S. §§ 7301–7315) requires residential sellers to disclose known material defects to buyers (§ 7303). The state-mandated disclosure form covers 'presence of hazardous substances' at § 7304(b)(14) — where any known elevated radon test result or existing mitigation system is recorded. Sellers who have never tested are not required to test: § 7308 imposes no affirmative duty to investigate. In Allentown, the practical reality is that most buyers request radon testing during the inspection contingency period. Sellers who test and mitigate before listing eliminate the most common contract contingency and preserve negotiating position.
Which ZIP codes does the Allentown radon data cover?
The Allentown radon dataset on this page covers ZIP codes 18052, 18101, 18102, 18103, 18104, and 18109. These are the ZCTAs assigned to Allentown in the Census 2020 ZCTA-to-Place relationship file and used for the PA DEP RadonZip Tool aggregation. Neighboring ZIP codes belong to adjacent municipalities and appear on their own PA Radon Hub pages.
Are Allentown-area public schools subject to SB 760?
Lehigh County is in EPA Zone 1 and is served by 10 school districts, including Allentown City School District. Pennsylvania Senate Bill 760, if enacted as drafted, would apply to all public school buildings in Lehigh County regardless of which district operates them. The bill remains in committee. Buildings in Zone 1 counties like Lehigh County would be highest priority under the proposed framework. If SB 760 is enacted, mitigation timelines, thresholds, and qualifying buildings would be set by the final bill text and any subsequent DEP implementing regulations. PA Radon Hub tracks this legislation; specific deadlines remain pending.
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