Pennsylvania · county radon data
Radon in Westmoreland County, Pennsylvania
41.1% of the 4,396 home radon tests on record here reached the EPA action level — mid-pack for the state, ranked #47 of 67 tested Pennsylvania counties.
What the numbers say
Westmoreland County sits 7.9 points below the Pennsylvania median (49% of tests over the limit across the state's counties). The median reading among its 4,396 reported tests was 3.1 pCi/L — and the single highest test on record reached 266.7 pCi/L, more than 66× the action level. EPA maps place the county in Radon Zone 1 — its highest-potential category, where average indoor screening levels are predicted above 4 pCi/L.
Why: the ground under Westmoreland County
Sits on Pennsylvania's folded Appalachian sedimentary rock — sandstones, shales, and carbonates that carry enough uranium that every county in the state has produced homes above the EPA action level. PA DEP calls radon a statewide concern. (Regional attribution here is well supported; unit-level detail is coarser — see methodology.)
Geology sources: PA DEP Radon Division · USGS OFR 93-292-C.
The housing stock factor
The median Westmoreland County home dates to 1964 — decades before radon-resistant new construction entered building codes. With 352,500 residents largely housed in that older stock, testing is the only way any individual household knows where it stands.
Radon by ZIP in Westmoreland County
Pennsylvania is one of the few states publishing actual test results at ZIP level (PA DEP residential data, 1986–2026) — county averages hide a lot; this doesn't.
| ZIP | Place | Tests | % ≥ 4 pCi/L | Max |
|---|---|---|---|---|
| 15628 | Donegal | 40 | 70% | 103 |
| 15671 | New Derry | 62 | 61.3% | 59.4 |
| 15944 | New Florence | 167 | 57.5% | 81.7 |
| 15670 | New Alexandria | 263 | 56.7% | 57.3 |
| 15687 | Stahlstown | 129 | 56.6% | 212.4 |
| 15678 | Rillton | 43 | 53.5% | 31.4 |
| 15666 | Mount Pleasant | 116 | 50.9% | 81.6 |
| 15698 | Yukon | 38 | 50% | 39.3 |
| 15479 | Smithton | 93 | 49.5% | 28 |
| 15623 | Claridge | 89 | 49.4% | 57.9 |
| 15923 | Bolivar | 89 | 49.4% | 80.3 |
| 15676 | Pleasant Unity | 53 | 49.1% | 52.2 |
| 15658 | Ligonier | 2,090 | 47.5% | 124 |
| 15677 | Rector | 130 | 46.9% | 35.4 |
| 15679 | Ruffs Dale | 141 | 45.4% | 55 |
| 15632 | Export | 1,916 | 44.2% | 776.5 |
| 15613 | Apollo | 296 | 43.9% | 443.1 |
| 15644 | Jeannette | 2,912 | 42.9% | 202 |
| 15668 | Murrysville | 181 | 42.5% | 47.4 |
| 15650 | Latrobe | 4,219 | 39.9% | 208 |
| 15656 | Leechburg | 600 | 39.7% | 121.9 |
| 15637 | Herminie | 159 | 39.6% | 241.4 |
| 15627 | Derry | 723 | 38.5% | 51.2 |
| 15601 | Greensburg | 13,038 | 38.2% | 167.5 |
| 15068 | New Kensington | 524 | 37.6% | 190 |
| 15089 | West Newton | 585 | 37.6% | 75 |
| 15661 | Loyalhanna | 66 | 36.4% | 19.6 |
| 15688 | Tarrs | 33 | 36.4% | 7.6 |
| 15062 | Monessen | 635 | 35.7% | 937 |
| 15641 | Hyde Park | 34 | 35.3% | 28.5 |
| 15639 | Hunker | 211 | 35.1% | 31.3 |
| 15665 | Manor | 282 | 35.1% | 118.3 |
| 15634 | Grapeville | 44 | 34.1% | 45.8 |
| 15683 | Scottdale | 672 | 33.9% | 65.4 |
| 15636 | Harrison City | 944 | 33.4% | 1060 |
| 15663 | Madison | 42 | 33.3% | 49.8 |
| 15672 | New Stanton | 468 | 33.1% | 303 |
| 15692 | Westmoreland City | 141 | 32.6% | 38 |
| 15085 | Trafford | 1,396 | 32.3% | 5483 |
| 15610 | Acme | 283 | 31.8% | 261.2 |
| 15697 | Youngwood | 452 | 31.6% | 34.9 |
| 15675 | Penn | 86 | 29.1% | 27.3 |
| 15655 | Laughlintown | 137 | 27.7% | 32.4 |
| 15012 | Belle Vernon | 77 | 27.3% | 68.3 |
| 15620 | Bradenville | 54 | 25.9% | 13.8 |
| 15642 | Irwin | 112 | 25% | 27.5 |
| 15083 | Sutersville | 80 | 20% | 39.6 |
Westmoreland County in the Pennsylvania picture
| Westmoreland County | 41.1% over the limit | 4,396 tests |
| Pennsylvania's highest: Fulton County | 69.7% | 90 tests |
| Pennsylvania county median | 49% | 67 counties ranked |
| Share of all Pennsylvania tests from this county | 2.5% | |
Ranked nearby in Pennsylvania
- Cameron County — #44, 44.1% of 80 tests over the limit
- Lawrence County — #45, 42.9% of 1,119 tests over the limit
- Wyoming County — #46, 42.5% of 183 tests over the limit
- Pike County — #48, 40.3% of 331 tests over the limit
- Tioga County — #49, 40.3% of 260 tests over the limit
- Susquehanna County — #50, 40.1% of 173 tests over the limit
(Ranking neighbors — counties adjacent in the Pennsylvania test ranking, not necessarily on the map.)
High test? Fixes and real pricing: the Pennsylvania mitigation cost guide. Every statistic here traces to the methodology (CDC EPHT (labs), 2008–2017; zones: EPA; year built & population: ACS 5-year; ZIP results: PA DEP).
Westmoreland County radon FAQ
- Is radon high in Westmoreland County?
- 41.1% of 4,396 home tests reported to the CDC came back at or above the EPA action level of 4 pCi/L — 7.9 points below the Pennsylvania county median of 49%, ranking #47 of 67 tested counties. EPA classifies the county as Zone 1.
- Does an older home in Westmoreland County mean more radon risk?
- The county's median home was built in 1964 — before radon-resistant construction practices entered building codes in the 1990s, so most of the housing stock has no built-in radon protection. Construction age changes the odds, not the answer: only a test tells you about your house.
- Where do these Westmoreland County numbers come from?
- 4,396 aggregated home tests in the CDC's Environmental Public Health Tracking dataset (CDC EPHT 2008-2017). Median reading: 3.1 pCi/L; the highest recorded test hit 266.7 pCi/L. How we handle the data, including its limits, is documented on our methodology page.
- Which ZIP codes in Westmoreland County test highest?
- In PA DEP's residential results (1986–2026): 15628 (Donegal) — 70% of 40 tests over the limit; 15671 (New Derry) — 61.3% of 62 tests over the limit; 15944 (New Florence) — 57.5% of 167 tests over the limit. Full ZIP table below.