Pennsylvania · county radon data
Radon in York County, Pennsylvania
59.7% of the 7,893 home radon tests on record here reached the EPA action level — among the higher-testing counties in the state, ranked #12 of 67 tested Pennsylvania counties.
What the numbers say
York County sits 10.7 points above the Pennsylvania median (49% of tests over the limit across the state's counties). The median reading among its 7,893 reported tests was 5.4 pCi/L — and the single highest test on record reached 940.9 pCi/L, more than 235× 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 York County
Underlain by Cambrian–Ordovician limestone and dolomite of Pennsylvania's karst valleys. Karst conduits and clay-rich cavity fill concentrate radium and move radon-laden soil gas quickly — USGS work found roughly a third to two-thirds of tested homes over the EPA action level in these valley counties.
Geology sources: USGS OFR 93-292-C.
The housing stock factor
The median York County home dates to 1976 — decades before radon-resistant new construction entered building codes. With 462,924 residents largely housed in that older stock, testing is the only way any individual household knows where it stands.
Radon by ZIP in York 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 |
|---|---|---|---|---|
| 17309 | Brogue | 112 | 84.8% | 278.3 |
| 17321 | Fawn Grove | 254 | 73.6% | 120.2 |
| 17352 | New Park | 89 | 71.9% | 236.8 |
| 17366 | Windsor | 485 | 71.1% | 237.5 |
| 17368 | Wrightsville | 600 | 70.3% | 1040.9 |
| 17302 | Airville | 191 | 70.2% | 772.5 |
| 17322 | Felton | 477 | 69.4% | 445.4 |
| 17329 | Glenville | 375 | 69.3% | 454.9 |
| 17313 | Dallastown | 1,234 | 66.3% | 292 |
| 17362 | Spring Grove | 1,673 | 66.3% | 672.9 |
| 17363 | Stewartstown | 1,531 | 65.8% | 229.7 |
| 17356 | Red Lion | 2,822 | 64.1% | 487.5 |
| 17360 | Seven Valleys | 836 | 63.3% | 317.7 |
| 17327 | Glen Rock | 1,065 | 62.1% | 397.4 |
| 17407 | York | 346 | 60.4% | 202.3 |
| 17347 | Mount Wolf | 720 | 59.7% | 304.4 |
| 17402 | York | 5,778 | 58.6% | 260 |
| 17314 | Delta | 584 | 57.5% | 386.1 |
| 17406 | York | 2,314 | 57.5% | 409.5 |
| 17403 | York | 4,981 | 57.4% | 434.6 |
| 17408 | York | 2,297 | 57.4% | 203.1 |
| 17349 | New Freedom | 1,527 | 54.6% | 239.6 |
| 17404 | York | 4,852 | 54.1% | 534 |
| 17364 | Thomasville | 259 | 53.3% | 49.2 |
| 17361 | Shrewsbury | 1,347 | 52.1% | 137.5 |
| 17070 | New Cumberland | 795 | 51.2% | 281.8 |
| 17315 | Dover | 2,237 | 49.5% | 165 |
| 17019 | Dillsburg | 2,694 | 49.4% | 228 |
| 17331 | Hanover | 1,164 | 48% | 257.3 |
| 17339 | Lewisberry | 917 | 47.1% | 184 |
| 17345 | Manchester | 510 | 46.1% | 695.6 |
| 17319 | Etters | 1,369 | 43.8% | 343.4 |
| 17370 | York Haven | 481 | 42% | 176 |
| 17365 | Wellsville | 206 | 41.7% | 47.3 |
| 17401 | York | 356 | 27.2% | 24.1 |
York County in the Pennsylvania picture
| York County | 59.7% over the limit | 7,893 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 | 4.6% | |
Ranked nearby in Pennsylvania
- Perry County — #9, 62.5% of 548 tests over the limit
- Montour County — #10, 61.6% of 165 tests over the limit
- Cumberland County — #11, 61% of 4,713 tests over the limit
- Northumberland County — #13, 59.5% of 658 tests over the limit
- Clearfield County — #14, 57.8% of 552 tests over the limit
- Jefferson County — #15, 57.7% of 413 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).
York County radon FAQ
- Is radon high in York County?
- 59.7% of 7,893 home tests reported to the CDC came back at or above the EPA action level of 4 pCi/L — 10.7 points above the Pennsylvania county median of 49%, ranking #12 of 67 tested counties. EPA classifies the county as Zone 1.
- Does an older home in York County mean more radon risk?
- The county's median home was built in 1976 — 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 York County numbers come from?
- 7,893 aggregated home tests in the CDC's Environmental Public Health Tracking dataset (CDC EPHT 2008-2017). Median reading: 5.4 pCi/L; the highest recorded test hit 940.9 pCi/L. How we handle the data, including its limits, is documented on our methodology page.
- Which ZIP codes in York County test highest?
- In PA DEP's residential results (1986–2026): 17309 (Brogue) — 84.8% of 112 tests over the limit; 17321 (Fawn Grove) — 73.6% of 254 tests over the limit; 17352 (New Park) — 71.9% of 89 tests over the limit. Full ZIP table below.