York County Radon Levels: What the Data Actually Says
Updated
York County is an EPA Radon Zone 1 county, meaning a predicted average indoor screening level above 4 pCi/L. Beyond that, be careful: the county averages published online disagree with each other by a wide margin because they draw on different self-selected datasets. The only figure here from a primary source is PA DEP's: approximately 40 percent of homes tested in Pennsylvania read above 4 pCi/L.
The one number with a primary source behind it
The Pennsylvania Department of Environmental Protection states, on its own radon page, that "approximately 40% of homes tested in Pennsylvania have radon levels above the Environmental Protection Agency's action guideline of 4 picocuries per liter (pCi/L)", and that "Pennsylvania has one of the most serious radon problems in the United States."
For scale, the national average indoor level is about 1.3 pCi/L. Pennsylvania is genuinely an outlier, and that part is not marketing.
Why the county averages you find online disagree
Search for a York County radon average and you will get a confident number. Search again and you will get a different confident number. We checked four sources and got a spread from roughly 9.85 to 13.2 pCi/L, which is not a rounding difference, it is a factor of a third.
There are three reasons, and none of them involve anyone lying.
Different datasets
Several of these figures come from a single test-kit vendor's customer results. That vendor's customers are not a random sample of York County houses. Different vendors, different customers, different numbers.
Short-term and long-term tests mixed together
A 48-hour test taken in February with the windows shut reads higher than a 365-day average of the same house. Aggregate both into one mean and the mean drifts upward by an amount nobody can quantify after the fact.
Self-selection
People test because they suspect a problem, because they are buying or selling, or because a neighbour found something. Houses nobody worried about are underrepresented in every dataset that exists. Every published average is therefore biased high to an unknown degree.
What a county average cannot do
It cannot tell you about your house, and that is not a technicality. Radon concentration depends on the uranium content of the soil directly under that foundation, the permeability of that soil, the specific cracks and penetrations in that slab, and how hard that building pulls air upward through its own stack effect. Two houses built in the same year by the same builder on the same street can test several pCi/L apart.
A short-term test kit costs about fifteen dollars and answers the question properly. Every county-average article on the internet, including this one, is a worse source of information about your house than that kit is.
What the Zone 1 designation does and does not mean
The EPA Map of Radon Zones sorts every county into one of three categories based on predicted average indoor screening levels. Zone 1 is above 4 pCi/L, Zone 2 is 2 to 4, Zone 3 is below 2. York County is Zone 1, as is most of Pennsylvania.
The EPA is explicit that the map is a planning and targeting tool, not a prediction for individual homes, and that homes in Zone 3 counties can still have elevated levels. So Zone 1 is a good reason to test and a bad reason to either panic or to skip testing because you assume you already know the answer.
What is actually worth knowing locally
- York County is Zone 1, and so is every county bordering it
- Roughly 40 percent of tested Pennsylvania homes exceed the action level, per DEP
- Basements read higher than upper floors, so where a test sits changes the number
- Winter readings run higher than summer readings in the same house
- New, tight, well-insulated construction can read higher than a draughty old farmhouse, because less air exchange means less dilution
- Nothing about the house's appearance, age or price predicts the result
The geology behind all of this is on why Pennsylvania is a radon state. What to do with a number once you have one is on your result came back high, and how to get a number you can trust is on short-term vs long-term tests.
Radon test data by township and borough
Each page below pulls the PA DEP test records for that municipality's ZIP codes, its housing stock and its geology. Sorted by the share of tests at or above 4.0 pCi/L.
| Municipality | Tests | 4+ pCi/L | 20+ pCi/L |
|---|---|---|---|
| Railroad | 37 | 83.8% | 8.1% |
| Windsor Borough | 864 | 67.1% | 28.2% |
| Dallastown | 2,420 | 65.7% | 23.1% |
| Yoe | 2,420 | 65.7% | 23.1% |
| Fawn Township | 621 | 65.2% | 21.2% |
| Cross Roads | 952 | 65.2% | 26.3% |
| Felton | 952 | 65.2% | 26.3% |
| Fawn Grove | 460 | 64.8% | 20.4% |
| East Hopewell Township | 4,344 | 64.6% | 22.9% |
| Stewartstown | 2,814 | 63.8% | 21.4% |
| Seven Valleys | 1,543 | 63.4% | 24.7% |
| North Hopewell Township | 9,107 | 62.2% | 20.9% |
| Jacobus | 714 | 62.2% | 20.6% |
| Springfield Township | 3,340 | 62% | 22.5% |
| Chanceford Township | 6,509 | 62% | 21% |
| Winterstown | 6,293 | 61.6% | 20.7% |
| Red Lion | 5,341 | 60.9% | 19.7% |
| Glen Rock | 1,797 | 60.8% | 20.6% |
| Lower Chanceford Township | 1,389 | 60.5% | 20.6% |
| Codorus Township | 5,413 | 59.6% | 22.7% |
| Manheim Township | 5,413 | 59.6% | 22.7% |
| Jefferson | 3,003 | 58.6% | 22.9% |
| Spring Grove | 3,003 | 58.6% | 22.9% |
| Mount Wolf | 1,258 | 58.1% | 19.5% |
| Hopewell Township | 5,544 | 58% | 16.4% |
| Delta | 972 | 57.4% | 18.7% |
| Peach Bottom Township | 972 | 57.4% | 18.7% |
| Windsor Township | 16,927 | 57.2% | 16% |
| York Township | 26,831 | 57% | 16% |
| Wrightsville | 1,351 | 56.9% | 16.3% |
| Loganville | 9,933 | 56.5% | 16.7% |
| North Codorus Township | 8,426 | 55.6% | 17.6% |
| Lower Windsor Township | 6,240 | 55.5% | 16.7% |
| Shrewsbury Township | 4,527 | 55.5% | 14.9% |
| East Prospect | 1,446 | 55.4% | 15.8% |
| Spring Garden Township | 8,348 | 55.2% | 15.2% |
| Springettsbury Township | 14,747 | 54.1% | 13.5% |
| Jackson Township | 7,319 | 53.7% | 15.5% |
| Hellam Township | 5,376 | 53.7% | 14.8% |
| Hallam | 4,025 | 52.6% | 14.3% |
| Yorkana | 4,025 | 52.6% | 14.3% |
| New Freedom | 2,730 | 52% | 11.2% |
| Shrewsbury Borough | 2,117 | 52% | 9.6% |
| York City | 17,149 | 51.9% | 10.3% |
| Manchester Township | 12,221 | 51.3% | 8.8% |
| North York | 8,196 | 50.7% | 6.1% |
| West York | 8,196 | 50.7% | 6.1% |
| East Manchester Township | 2,241 | 50.6% | 13% |
| West Manchester Township | 12,076 | 50.5% | 7.6% |
| New Salem | 3,916 | 50.3% | 10.7% |
| Heidelberg Township | 14,823 | 49.4% | 14.5% |
| Paradise Township | 689 | 49.2% | 6.4% |
| Conewago Township | 17,245 | 49.1% | 7.7% |
| Carroll Township | 5,858 | 47.4% | 6.9% |
| Dillsburg | 5,858 | 47.4% | 6.9% |
| Franklin Township | 5,858 | 47.4% | 6.9% |
| Franklintown | 5,858 | 47.4% | 6.9% |
| Hanover | 11,820 | 47% | 12.4% |
| West Manheim Township | 11,820 | 47% | 12.4% |
| Monaghan Township | 8,109 | 46.6% | 6.6% |
| Washington Township | 6,442 | 46.4% | 6.7% |
| Warrington Township | 8,448 | 46% | 6.5% |
| Lewisberry | 2,150 | 44.9% | 5.8% |
| Dover Township | 4,041 | 44.2% | 5% |
| Dover Borough | 4,041 | 44.2% | 5% |
| Fairview Township | 7,156 | 43.4% | 6.9% |
| Goldsboro | 2,905 | 42.1% | 6.4% |
| Newberry Township | 3,939 | 41.8% | 6% |
| Manchester Borough | 983 | 41% | 4.6% |
| York Haven | 1,034 | 40.8% | 4.7% |
| Wellsville | 440 | 33.6% | 4.5% |
Source: PA DEP radon test results, 98,845 York County tests, 1986 to 2026. ZIP codes cross municipal lines, so neighboring rows share some tests.
Common questions
What is the average radon level in York County PA?
There is no single authoritative figure. Published averages range from roughly 9.85 to 13.2 pCi/L across different aggregators, and they are measuring different things: different vendors' customer results, different mixes of short-term and long-term tests, and all of them self-selected. A county average also cannot be applied to an individual address.
Is York County a Zone 1 radon county?
Yes. The EPA Map of Radon Zones places York County in Zone 1, the highest of three categories, defined as a predicted average indoor screening level greater than 4 pCi/L. Most of Pennsylvania is Zone 1.
My neighbour tested low. Do I still need to test?
Yes. Radon levels differ between adjacent houses because what matters is the soil directly beneath that foundation and how that specific building draws air up from below. A neighbour's result is weak evidence about yours.
Have a number you want read?
Tell us the result and your town in York County, or call and read it out. We will tell you what it points to and what a system would involve in a house like yours.
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