Radon Testing & Mitigation in Clarion, PA
High radon potential. The Clarion River sandstone formation and surrounding Pennsylvanian shale produce uranium-bearing soils across Clarion County, with elevated indoor radon common in older homes.
High Radon Risk Area
Clarion sits in EPA Zone 1 — testing is recommended for every home regardless of age or foundation type.
Radon Testing in Clarion
In Clarion-area ZIP codes, 46% of 1,326 basement tests reported to PA DEP measured 4.0 pCi/L or higher, with a median of 3.7 pCi/L. Readings differ from house to house, so each home needs its own test. Start with a short-term test of 48–96 hours on the lowest lived-in level. A long-term test of 90 days or more averages out seasonal swings.
A result at or above EPA's 4.0 pCi/L action level calls for a confirming test or mitigation. Retest after a mitigation system goes in, and at least every two years from then on. Pennsylvania requires DEP certification for anyone who tests as a paid service; you may test your own home with a kit from a DEP-certified laboratory. For a home sale, read the Pennsylvania real estate radon testing guide.
Local Geology & Risk Factors
Clarion is located in an area with Appalachian Plateau / Clarion River Sandstone Formation 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 →
Quick Facts
- Median home value: $155,300 · Median year built: 1962
- Population: 4,202
- Foundation types: Basement (most common); Crawlspace (moderate); Slab-on-grade (varies)
Clarion County Context
Clarion is a municipality of Clarion County, EPA Zone 1. Zone designation is assigned at the county level, so Clarion inherits its classification; countywide aggregate figures live on the county page.
See Clarion County radon aggregate data →Measured Radon Data for Clarion
These figures cover every test whose ZIP code is listed above. ZIP codes do not follow municipal lines, so the figures describe Clarion-area ZIP codes, not the municipal boundary of Clarion. They count tests, not homes.
Source: PA Department of Environmental Protection, Radon Test Results, data.pa.gov. Tests through July 2026. Retrieved September 29, 2026.
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Radon Mitigation Cost in Clarion
Active sub-slab depressurization (ASD) systems in Clarion typically cost $900–$2,150. 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 (moderate)
- Slab-on-grade (varies)
Systems used in the region
- Active sub-slab depressurization
- Sump pit depressurization
- Passive soil depressurization
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 Clarion, Clarion 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
Why is radon a concern in Clarion, PA?
Clarion sits on the Clarion River sandstone formation, which contains elevated radium-226. Clarion County is EPA Zone 1. 46% of the 1,326 basement tests reported to PA DEP from Clarion-area ZIP codes measured 4.0 pCi/L or higher.
What does radon mitigation cost in Clarion County?
Most Clarion County mitigation systems run $900–$2,150 installed. Active sub-slab depressurization is the standard approach. Older Clarion-area homes with crawlspaces or partial basements sometimes require multi-zone systems, which increase costs toward the upper end of the range.
Does the Clarion River affect indoor radon?
Surface water is not a material indoor air pathway at municipal treatment scales. But the river-valley topography concentrates cold air drainage, increasing wintertime stack effect in basement homes. Combined with the underlying Clarion sandstone, this produces seasonal radon elevation patterns.
What share of radon tests in Clarion-area ZIP codes are at or above the EPA action level?
46% of the 1,326 basement tests reported to PA DEP from Clarion-area ZIP codes measured 4.0 pCi/L or higher, 9 points above the 37% statewide share. The median result is 3.7 pCi/L. Of 196 first-floor tests, 24% measured 4.0 pCi/L or higher. The figures cover the ZIP codes listed on this page, not the municipal boundary, and they count tests, not homes.
Do homes in Clarion need to be tested for radon?
Clarion County is EPA Zone 1 — the highest radon-potential classification — so every home in Clarion 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 Clarion?
Active sub-slab depressurization (ASD) systems in the Clarion area typically cost $900–$2,150. 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 Clarion?
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 Clarion, 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 Clarion radon data cover?
The Clarion radon dataset on this page covers ZIP code 16214. These are the ZCTAs assigned to Clarion in the Census 2020 ZCTA-to-Place relationship file, and the page counts every test in the PA DEP record on data.pa.gov that carries one of them. A ZIP code can reach into a neighboring municipality, so the figures describe these ZIP codes rather than Clarion's municipal boundary.
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