Radon Testing & Mitigation in Johnstown, PA
High radon risk driven by the Pennsylvanian Coal Measures of the Appalachian Plateau. Johnstown's valley-floor neighborhoods sit above shale, sandstone, and coal seams with trace uranium enrichment typical of the Allegheny Group, while hillside homes above former mines contend with abandoned-mine soil gas migration. The city's older housing stock, steep topography, and pronounced wintertime stack effect combine to produce consistently elevated basement radon readings across Cambria County.
Moderate Radon Risk Area
Johnstown sits in EPA Zone 2 — testing is recommended for every home regardless of age or foundation type.
Radon Testing in Johnstown
In Johnstown-area ZIP codes, 43% of 6,511 basement tests reported to PA DEP measured 4.0 pCi/L or higher, with a median of 3.5 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
Johnstown is located in an area with Appalachian Plateau / Pennsylvanian Coal Measures 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: $42,100 · Median year built: 1943
- Population: 18,245
- Foundation types: Full basement (predominant across steel-era neighborhoods); Block-wall basement (mid-century hillside construction); Walkout basement (hillside homes above former mine workings)
Cambria County Context
Johnstown is a municipality of Cambria County, EPA Zone 2. Zone designation is assigned at the county level, so Johnstown inherits its classification; countywide aggregate figures live on the county page.
See Cambria County radon aggregate data →Measured Radon Data for Johnstown
These figures cover every test whose ZIP code is listed above. ZIP codes do not follow municipal lines, so the figures describe Johnstown-area ZIP codes, not the municipal boundary of Johnstown. 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 Johnstown
Active sub-slab depressurization (ASD) systems in Johnstown typically cost $825–$2,250. 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
- Full basement (predominant across steel-era neighborhoods)
- Block-wall basement (mid-century hillside construction)
- Walkout basement (hillside homes above former mine workings)
Systems used in the region
- Active sub-slab depressurization
- Block wall depressurization
- Sub-membrane depressurization (crawlspace additions)
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 Johnstown, Cambria 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
Do former coal mines beneath Johnstown affect residential radon?
Yes, indirectly. The Pennsylvanian Coal Measures that made Johnstown a steel-and-coal city also produce radon through trace uranium in the overlying shale and sandstone. Abandoned mine workings beneath portions of the city and its suburbs can act as soil-gas conduits, concentrating radon into permeable backfill and basements on hillside lots. Mitigation strategy depends on foundation type and proximity to documented mine voids.
Why does Johnstown's radon risk differ from Pittsburgh's despite similar coal geology?
Both cities sit on the Pennsylvanian section of the Appalachian Plateau, but Johnstown's tighter valley topography and older, predominantly basement-equipped housing stock produce more pronounced stack-effect accumulation than Pittsburgh's mixed foundation mix. Despite Cambria County's EPA Zone 2 classification — a lower baseline than Allegheny County's Zone 1-to-2 transition areas — measured testing averages in Johnstown's valley-floor neighborhoods run consistently higher because of these local conditions.
How do Johnstown's hillside walkout basements affect mitigation design?
Hillside walkout basements change the pressure dynamics that drive radon entry. A DEP-certified contractor will diagnose whether the sub-slab pressure field can be established from a single suction pit or whether two-pit designs are required to cover daylight-exposed walls. Block-wall depressurization is often added on homes with hollow-core foundations to prevent bypass through the wall cavities.
What share of radon tests in Johnstown-area ZIP codes are at or above the EPA action level?
43% of the 6,511 basement tests reported to PA DEP from Johnstown-area ZIP codes measured 4.0 pCi/L or higher, 6 points above the 37% statewide share. The median result is 3.5 pCi/L. Of 383 first-floor tests, 22% 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 Johnstown need to be tested for radon?
Cambria County is EPA Zone 2, meaning the county has moderate radon potential and elevated readings are common enough that all Johnstown homes should be tested. 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 Johnstown?
Active sub-slab depressurization (ASD) systems in the Johnstown area typically cost $825–$2,250. 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 Johnstown?
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 Johnstown, 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 Johnstown radon data cover?
The Johnstown radon dataset on this page covers ZIP codes 15901, 15902, 15905, and 15906. These are the ZCTAs assigned to Johnstown 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 Johnstown's municipal boundary.
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