Pennsylvania · county radon data
Radon in Berks County, Pennsylvania
52.6% of the 7,522 home radon tests on record here reached the EPA action level — mid-pack for the state, ranked #25 of 67 tested Pennsylvania counties.
What the numbers say
Berks County sits 3.6 points above the Pennsylvania median (49% of tests over the limit across the state's counties). The median reading among its 7,522 reported tests was 4.3 pCi/L — and the single highest test on record reached 1026.8 pCi/L, more than 256× 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 Berks County
Sits on or beside the Reading Prong — a belt of uranium-bearing Precambrian granite and gneiss that produces some of the highest indoor radon readings in the United States. This is the geology behind the famous 1984 Stanley Watras case in Berks County (a home near Boyertown measured extreme radon), the discovery that launched America's radon programs. Fractured crystalline rock and thin soils let radon move efficiently into basements.
Geology sources: USGS OFR 93-292-C · PA DEP Radon Division · Watras/Boyertown 1984 (PMC4629742).
The housing stock factor
The median Berks County home dates to 1969 — decades before radon-resistant new construction entered building codes. With 433,015 residents largely housed in that older stock, testing is the only way any individual household knows where it stands.
Radon by ZIP in Berks 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 |
|---|---|---|---|---|
| 19506 | Bernville | 1,211 | 63% | 426.8 |
| 19609 | Reading | 1,658 | 62.1% | 239.6 |
| 19541 | Mohrsville | 639 | 61.3% | 247.4 |
| 19540 | Mohnton | 33 | 60.6% | 149.7 |
| 19529 | Kempton | 352 | 59.9% | 444.5 |
| 19534 | Lenhartsville | 229 | 59.8% | 170.8 |
| 19567 | Womelsdorf | 455 | 59.3% | 136.8 |
| 19555 | Shoemakersville | 299 | 58.2% | 179 |
| 19526 | Hamburg | 1,148 | 57.4% | 146.7 |
| 19547 | Oley | 706 | 57.2% | 1397.8 |
| 19551 | Robesonia | 612 | 56.4% | 432.1 |
| 19533 | Leesport | 1,083 | 56.2% | 394.6 |
| 19554 | Shartlesville | 34 | 55.9% | 36.5 |
| 19605 | Reading | 2,276 | 54.1% | 447.4 |
| 19545 | New Berlinville | 45 | 53.3% | 16.8 |
| 19560 | Temple | 680 | 52.4% | 269 |
| 19510 | Blandon | 1,475 | 51.9% | 106.7 |
| 19522 | Fleetwood | 2,230 | 51.9% | 1204.7 |
| 19539 | Mertztown | 577 | 51.6% | 313 |
| 19507 | Bethel | 191 | 50.3% | 199.8 |
| 19610 | Reading | 3,830 | 50.3% | 234 |
| 19565 | Wernersville | 1,197 | 50.2% | 199.4 |
| 19530 | Kutztown | 1,578 | 48.4% | 674.6 |
| 19608 | Reading | 4,502 | 47% | 451.7 |
| 19606 | Reading | 4,946 | 46.8% | 2836.6 |
| 19504 | Barto | 277 | 45.8% | 87.4 |
| 19562 | Topton | 257 | 45.1% | 49.7 |
| 19505 | Bechtelsville | 493 | 44.4% | 256.5 |
| 19607 | Reading | 2,732 | 44% | 240 |
| 18056 | Hereford | 55 | 41.8% | 59.4 |
| 19604 | Reading | 566 | 41.2% | 47.1 |
| 19611 | Reading | 765 | 40.5% | 55.5 |
| 19518 | Douglassville | 3,195 | 39.6% | 452.5 |
| 19601 | Reading | 743 | 39.3% | 197 |
| 19602 | Reading | 281 | 39.1% | 99.2 |
| 18011 | Alburtis | 60 | 38.3% | 92.1 |
| 19543 | Morgantown | 1,286 | 35.5% | 367.9 |
| 19503 | Bally | 238 | 30.7% | 71.5 |
| 19508 | Birdsboro | 2,070 | 29.1% | 79.9 |
| 19512 | Boyertown | 239 | 25.1% | 110.9 |
Berks County in the Pennsylvania picture
| Berks County | 52.6% over the limit | 7,522 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 | 4.3% | |
Ranked nearby in Pennsylvania
- Warren County — #22, 54.6% of 364 tests over the limit
- Bedford County — #23, 54.4% of 495 tests over the limit
- Carbon County — #24, 54.4% of 818 tests over the limit
- Lycoming County — #26, 52.5% of 1,273 tests over the limit
- Potter County — #27, 52.1% of 138 tests over the limit
- Indiana County — #28, 51.5% of 745 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).
Berks County radon FAQ
- Is radon high in Berks County?
- 52.6% of 7,522 home tests reported to the CDC came back at or above the EPA action level of 4 pCi/L — 3.6 points above the Pennsylvania county median of 49%, ranking #25 of 67 tested counties. EPA classifies the county as Zone 1.
- Does an older home in Berks County mean more radon risk?
- The county's median home was built in 1969 — 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 Berks County numbers come from?
- 7,522 aggregated home tests in the CDC's Environmental Public Health Tracking dataset (CDC EPHT 2008-2017). Median reading: 4.3 pCi/L; the highest recorded test hit 1026.8 pCi/L. How we handle the data, including its limits, is documented on our methodology page.
- Which ZIP codes in Berks County test highest?
- In PA DEP's residential results (1986–2026): 19506 (Bernville) — 63% of 1,211 tests over the limit; 19609 (Reading) — 62.1% of 1,658 tests over the limit; 19541 (Mohrsville) — 61.3% of 639 tests over the limit. Full ZIP table below.