Radon Testing & Mitigation in Armstrong County, PA
Radon in Armstrong County: 54% of the 4,615 basement tests reported to PA DEP measured 4.0 pCi/L or higher, EPA's action level, 17 points above the 37% statewide share. The median result is 4.3 pCi/L, and the county ranks 14th highest of 67. First-floor tests run lower: 28% at or above 4.0. Every home here should be tested.
Radon Testing in Armstrong County
A test is the only way to learn a specific Armstrong County home's radon level. The share of basement tests at or above 4.0 pCi/L, 54% of 4,615 reported to PA DEP, describes the county, not any one house. Short-term tests run 48–96 hours and give a first reading; long-term tests run 90 days or longer and better reflect the annual average.
EPA's action level is 4.0 pCi/L. At or above it, confirm with a follow-up test or move to mitigation, then retest once a system is installed and at least every two years after. Under 25 Pa. Code § 240, anyone testing for radon as a service in Pennsylvania must hold current DEP certification; homeowners may test their own home with a kit from a DEP-certified laboratory. Buying or selling? See radon testing in Pennsylvania real estate transactions.
More Than Half of Armstrong Basement Tests Reach the Action Level
Armstrong County has 4,615 basement radon tests on record with PA DEP, and 54% of them measured 4.0 pCi/L or higher. EPA sets the action level for mitigation at 4.0 pCi/L. The median result is 4.3 pCi/L, so the middle test in the county record is itself above the number at which EPA tells homeowners to install a mitigation system.
First-floor results run lower. Of 572 first-floor tests, 28% measured 4.0 pCi/L or higher, against 20% statewide, and the median is 1.9 pCi/L. Most of the elevated results in Armstrong are below grade. In a home where the basement is finished, used as a bedroom, or connected to the living space by an open stair, the basement result is the exposure — there is no unoccupied buffer floor absorbing it.
Set against the rest of the Commonwealth, Armstrong ranks 14th highest of 67 counties by share of basement tests at or above 4.0 pCi/L. The statewide share is 37% across 2,629,492 basement tests; Armstrong is 17 points above it.
How Armstrong Compares With the Counties Around It
Armstrong shares county lines with five Pennsylvania counties. By share of basement tests at or above 4.0 pCi/L, Jefferson is higher at 56%; Clarion at 48%, Butler at 47%, Indiana at 46%, and Westmoreland at 40% are lower. Armstrong, at 54%, sits near the top of its region without leading it.
The underlying rock explains part of it. Armstrong sits on Appalachian Plateau bedrock — Allegheny River valley formations of Pennsylvanian sandstone and shale carrying elevated radium-226, the parent isotope that decays to radon. That is the same plateau section that runs beneath Allegheny County to the southwest, where 34% of basement tests reached the action level, so the bedrock alone does not account for the difference in measured indoor radon.
Topography and housing depth play a part. Kittanning, the county seat, is built as a hillside-and-floodplain settlement along the Allegheny River. That pattern produces widely varying foundation depths across short distances — homes cut into a slope sit deeper into the weathered bedrock than homes on the terrace below, and depth into fractured rock is the strongest control on how much soil gas reaches a slab.
The housing stock is old and basement-heavy. The Census-reported median year built for owner-occupied housing in Armstrong County is 1960; in Kittanning borough itself it is 1946. Pre-1950 and mid-century construction in this region means block or poured basement walls with unsealed cold joints, floor drains, and no sub-slab vapor barrier — a full set of soil-gas entry points under a heated living space.
No Mitigation Firm Is Based in the County
The PA DEP Certified Mitigation Firms Directory lists zero DEP-certified mitigation firms with a business address in Armstrong County. Allegheny and Westmoreland each list five and Butler one. The practical consequence is scheduling: work in Armstrong is performed by certified professionals traveling in, which affects lead time more than it affects price.
That travel radius is why the county record matters to a homeowner here more than an individual anecdote does. With no local firm, there is no informal local knowledge circulating about which streets test high. The DEP dataset is the record, and it shows more than half of Armstrong basement tests at or above the action level.
Armstrong County homes carry a median owner-occupied value of $146,300 and, in the Kittanning area, a median sale price of $130,000. Buyers here commonly request radon testing during the inspection contingency window before closing. With more than half of the county's basement tests at or above the action level, a seller who has not tested may end up negotiating a mitigation credit rather than a discretionary repair — which is an argument for testing before the listing goes up, not after an inspection report lands.
Measured Radon Data for Armstrong County
Source: PA Department of Environmental Protection, Radon Test Results, data.pa.gov. Tests through July 2026. Retrieved September 29, 2026. Figures count tests, not homes. A home tested more than once is counted each time, and tests run after a mitigation system was installed are included because the dataset does not separate them.
Read the grid against the rest of the state. Armstrong ranks 14th highest of 67 counties by share of basement tests at or above 4.0 pCi/L and 48th by test volume — a high share on a comparatively small sample. ZIP 16201, the Kittanning area, accounts for 1,324 of the 4,615 basement tests, and 58% of those measured 4.0 pCi/L or higher.
No DEP-certified mitigation firms are physically based in Armstrong County. Certified professionals from adjacent counties (Westmoreland County (5 firms), and Butler County (1 firm)) travel here to perform testing and mitigation.
Source: PA DEP Certified Mitigation Firms Directory, July 2026. This reflects business address only — firms based elsewhere may also serve Armstrong County.
Cities and Boroughs in Armstrong County
Kittanning is the Armstrong County municipality with its own PA Radon Hub page. It holds the Kittanning-area figures, the local mitigation cost range, and connections to DEP-certified professionals serving the county.
Adjacent Counties
Of the five counties Armstrong borders, only Jefferson has a higher share of basement tests at or above 4.0 pCi/L, at 56%. The other four run from 40% in Westmoreland to 48% in Clarion. If you are comparing a property here against one across a county line, these are the pages with the measured numbers.
Comparing radon risk across the wider Commonwealth? Browse All 67 Pennsylvania county radon pages for EPA zone classification and measured basement averages statewide.
Connect with a DEP-Certified Radon Professional
Submit your request and we will connect you with a DEP-certified professional serving Armstrong County. All providers verified against the PA Department of Environmental Protection Bureau of Radiation Protection directory.
(717) 461-2427Connect with a DEP-certified radon proPA Radon Hub is an independent informational resource. We do not perform radon testing or mitigation. We connect Pennsylvania property owners with independent, DEP-certified professionals — verify any contractor's certification at dep.pa.gov/radon before hiring.
Testing and Mitigation Options in Armstrong County
Where to Put the Detector in an Armstrong County Home
Test the lowest level you occupy or could plausibly finish. That is standard EPA guidance everywhere. In Armstrong, 28% of first-floor tests measured 4.0 pCi/L or higher, so a first-floor test here can return an actionable result on its own, but the basement is where most elevated results are found. Short-term charcoal canisters and continuous monitors run 48–96 hours at $15–$50. Long-term alpha-track detectors run 90 days or more and average out the heating-season stack effect that pushes winter readings above the annual mean.
What Mitigation Costs Here, and Why
Active sub-slab depressurization systems in the Kittanning area run $900–$2,200. Armstrong sits at the lower end of the statewide cost band because the dominant foundation type is a straightforward basement rather than a historic fieldstone or multi-level crawlspace assembly. High starting concentrations do not automatically mean an expensive system — they usually mean fan sizing and post-mitigation verification matter more, not that the installation is structurally harder.
Budget for the retest. Post-mitigation verification is the only thing that proves a system brought the level down.
Verifying an Out-of-County Contractor
Because no certified mitigation firm is based in Armstrong County, most contractors quoting work here will hold a business address in Allegheny, Butler, or another nearby county. That is normal and permitted — certification under 25 Pa. Code § 240 is statewide, not county-scoped. Ask for the DEP certification number and confirm it is current before signing a contract or accepting payment.
Frequently Asked Questions
Why do so many Armstrong County radon tests come back high?
Of the 4,615 basement tests reported to PA DEP from Armstrong County, 54% measured 4.0 pCi/L or higher, against 37% statewide, and the median result is 4.3 pCi/L. Three factors are in play: Appalachian Plateau bedrock of Pennsylvanian sandstone and shale carrying elevated radium-226; a hillside-and-floodplain settlement pattern along the Allegheny River that puts foundations at widely varying depths into weathered rock; and a basement-heavy housing stock with a county median year built of 1960 and a Kittanning borough median of 1946.
What does a result above 4.0 pCi/L mean in Armstrong County?
EPA sets 4.0 pCi/L as the level at which it recommends installing a mitigation system. In Armstrong County, 54% of 4,615 basement tests reached that level and 11% measured 20 pCi/L or higher. Those figures count tests across the county; they are not a prediction for any individual property — some Armstrong homes test below 4.0 and some test far above. The only way to know a specific home's number is to test that home.
Do Armstrong County homes need testing if the basement is unfinished?
Yes. Of 572 first-floor tests on record in Armstrong County, 28% measured 4.0 pCi/L or higher, against 20% statewide, so an unfinished basement does not reliably buffer the floor above it. Test the lowest occupied level, and if the basement is unfinished, test the first floor as well.
How much does radon mitigation cost in Armstrong County?
Active sub-slab depressurization systems in the Kittanning area typically cost $900–$2,200 installed. Standard basement installations on poured-concrete foundations fall at the lower end; block-wall depressurization, multi-point suction, and crawlspace encapsulation push toward the upper end. A high starting concentration does not by itself raise the price — it raises the importance of correct fan sizing and of post-mitigation verification. All work must be performed by a DEP-certified mitigation professional under 25 Pa. Code § 240.
Are there DEP-certified radon contractors in Armstrong County?
The PA DEP Certified Mitigation Firms Directory lists no mitigation firms with a business address in Armstrong County. Certified professionals from nearby counties — Allegheny and Westmoreland list five firms each, Butler one — travel here to perform testing and mitigation. DEP certification under 25 Pa. Code § 240 is statewide, so an out-of-county address is not a limitation; confirm the certification number is current before hiring.
Should I test before listing a home in Armstrong County?
Armstrong County buyers commonly request radon testing during the inspection contingency window before closing. With 54% of the county's basement tests at or above 4.0 pCi/L, a buyer's test may well return an actionable result, with a mitigation credit negotiated under time pressure. Pennsylvania's Real Estate Seller Disclosure Law (68 Pa.C.S. §§ 7301–7315) requires disclosure of known results but imposes no duty to test under § 7308 — so the decision to test before listing is a negotiating decision, not a legal one.
Which ZIP codes does the Armstrong County radon data cover?
The Armstrong County figures on this page count every test reported to PA DEP with an Armstrong County address: 4,615 basement tests and 572 first-floor tests. 21 ZIP codes have at least 20 basement tests on record in the county. The largest is 16201, the Kittanning area, with 1,324 basement tests, of which 58% measured 4.0 pCi/L or higher.
How does Armstrong County compare with the rest of Pennsylvania?
Armstrong ranks 14th highest of 67 counties by share of basement tests at or above 4.0 pCi/L, at 54% against 37% statewide. It is not the highest county in the Commonwealth — Fulton County is at 70% and Juniata at 62% — but it sits in the upper quartile, and among the five counties it borders only Jefferson, at 56%, is higher.
Related Reading
Independent resource — we do not perform testing. PA Radon Hub is an independent informational resource connecting Pennsylvania property owners with independent, DEP-certified radon professionals. We do not perform radon testing or mitigation. Verify contractor certification against the PA DEP Radon Services Directory before hiring.