Radon in Allegheny County, Pennsylvania

What Radon Mitigation Costs in Allegheny County, and How to Get It Done

Active sub-slab depressurization systems in the Pittsburgh area run $950–$2,400 installed. The spread reflects the county's housing mix more than its radon levels: a mid-century suburban poured-concrete basement is a routine single-suction installation, while a pre-war city rowhouse or a hillside home with stepped foundations and partial crawlspace may need multi-point suction or encapsulation work. A high radon reading does not by itself raise the price; foundation type does.

Allegheny is one of the better-supplied counties in Pennsylvania for certified mitigation work: five DEP-certified firms hold business addresses inside the county, with more serving it from Beaver, Westmoreland, and Washington. That depth of supply is a homeowner's advantage — you can reasonably ask for a certification number, a proposed suction-point layout, and a post-mitigation verification plan before committing, and compare more than one quote. Certification under 25 Pa. Code § 240 is mandatory for anyone performing radon testing or mitigation in the Commonwealth; confirm the number is current in the PA DEP Radon Services Directory before signing.

The reason to test in the first place is that the county average understates individual risk. Allegheny's 52,935 basement tests average 3.55 pCi/L — just below the 4.0 pCi/L action level — but that average spans 33 ZIP codes and widely varying terrain, and it sits close enough to the action level that a large share of tested homes came in above it. A DEP-certified contractor interviewed by PA Radon Hub reports Ross Township and Allison Park test consistently elevated. The county number tells you what the county looks like; only a test tells you what your home is.

EPA Zone 1 With a Sub-Action-Level Measured Average

Allegheny County is classified EPA Zone 1, the highest radon-potential classification, which predicts an average indoor radon level above 4.0 pCi/L. The measured basement average is 3.55 pCi/L. Those two statements are both true, and the gap between them is the most useful thing on this page.

The EPA Map of Radon Zones is a 1993 predictive classification built from geology, aerial radiometric survey, soil permeability, and foundation type. The PA DEP figures here are measured results from tests submitted between January 1990 and December 2025. A predictive model and three and a half decades of measurement are answering different questions, and where they disagree, the measurement wins for the county — but the model still describes the underlying potential.

By measured basement average, Allegheny ranks 62nd of the 67 counties in this dataset, against a statewide test-weighted average of 6.44 pCi/L. It also reads lowest among the six counties it borders: Armstrong averages 10.76 pCi/L, Butler 9.04, Beaver 8.12, Westmoreland 5.93, and Washington 4.03. Allegheny is the low-reading county in a high-reading region.

None of that makes an individual Allegheny home safe by default. An average of 3.55 pCi/L sits close enough to 4.0 that a large share of the 52,935 tested homes came in above the action level. The county number tells you what the county looks like; it tells you nothing about a specific address.

Conemaugh Group Bedrock and Pittsburgh Housing Stock

Allegheny sits on Appalachian Plateau bedrock — the coal-bearing Conemaugh Group, a cyclic sedimentary stack of sandstone, shale, and coal. Cyclic layering means repeated contacts between rock types of different permeability, and fractures running through that stack open soil-gas pathways into the structures above.

The housing stock is old and concentrated. Median year built for owner-occupied housing is 1957 countywide and 1942 in the city of Pittsburgh — a pre-war urban core surrounded by mid-century suburban build-out, across a county of 1,231,814 residents with a median owner-occupied home value of $216,700.

Terrain matters as much as age here. A DEP-certified mitigation contractor interviewed by PA Radon Hub reports that Ross Township and Allison Park test consistently elevated — a reminder that a 3.55 pCi/L county average is an average across steep, geologically varied ground, not a uniform condition. Hillside neighborhoods with deep-cut foundations behave differently from valley-floor construction a few miles away.

Five DEP-certified mitigation firms hold business addresses in Allegheny County, the largest concentration among the counties in this region and a practical advantage for scheduling both testing and installation.

Measured Radon Data for Allegheny County

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

The value of this grid is its denominator. 52,935 basement tests and 3,651 first-floor tests make Allegheny one of the few Pennsylvania counties where the measured averages are stable enough to be used as a reference point rather than an indication.

That stability is what separates the two columns above. The 234.0 pCi/L peak is a real result from a real home, and at this sample size it barely registers in the average — which is exactly the property that lets the 3.55 pCi/L figure carry weight. Treat the peak as evidence of the range that exists in Allegheny County, and the average as evidence of the center.

Cities and Boroughs in Allegheny County

Pittsburgh carries the Allegheny County dataset — 33 ZIP codes and 52,935 basement tests aggregated onto one municipal page. That page holds the ZIP-level DEP averages, the local cost range, and connections to DEP-certified professionals serving the county.

Adjacent Counties

Allegheny reads lower than all five counties it borders, and in the case of Armstrong the difference is a factor of three across one county line. If you are weighing a property in a neighboring county against one here, the measured numbers are on these pages.

Comparing radon risk across the wider Commonwealth? Browse All 67 Pennsylvania county radon pages for EPA zone classification and measured basement averages statewide.

Testing and Mitigation Options in Allegheny County

Frequently Asked Questions

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