Radon levels in York County, PA

Radon levels by ZIP code

Start with your own ZIP code rather than the county figure. The county average of 10.75 pCi/L is a useful headline and a poor guide to any particular street, because the range inside York County is wide.

No York County ZIP code matches that. Only ZIP codes with at least 300 recorded tests are listed, so a very small area may not appear.

Bands are ours rather than official: lower is under 8 pCi/L, elevated is 8 to 15, and high is 15 and above. The only official threshold is the EPA action level of 4 pCi/L, and every ZIP code here except 17401 has more than a third of its tests sitting at or above it.

The spread inside one county

Airville at 25.06 pCi/L and York at 2.83 sit in the same county, on the same fractured limestone and shale, about 8.9 times apart. That gap is the whole argument against treating a county map as an answer.

The heaviest readings sit in the rural south and west: Airville, Glenville, Felton, Windsor, Seven Valleys and Spring Grove all average above 17 pCi/L. The lightest sit to the north along the Susquehanna, around York Haven, Wellsville and Dover, between 5 and 6.5.

The genuine surprise is downtown. ZIP code 17401, the oldest and densest part of York city, averages 2.83 pCi/L with only 22.1 percent of tests at or above the action level, which makes it the lowest reading area in the county. That runs against the usual assumption that older housing means more radon, and it is a reminder that what matters is the ground and the foundation rather than the age of the building. The rest of York city reads very differently: 17404 averages 7.00 and 17403 and 17406 both sit above 11.

None of which tells you what is under your own slab. Two identical houses on one street can differ several times over, because entry depends on the cracks in your particular foundation and how your particular house is heated. The neighbourhood figure tells you whether testing is worth doing, and outside 17401 the answer in every York County ZIP code is a clear yes.

How to read these numbers honestly

Four things about this dataset are worth knowing before you lean on it, and most pages presenting radon data mention none of them.

1. These are tests people chose to take. Not a random sample of houses. Testing clusters around property sales and around people who already suspect a problem, which can pull an area's average in either direction.
2. Most readings are basement readings. Of the York County tests recording a floor level, 82.8 percent were taken in a basement, which is the highest point of any house. Your first floor bedroom will normally read lower than the figure here.
3. Mitigated houses are not flagged. The field that would tell us whether a system was already installed is recorded as not collected for every York County row, so some of these readings are from houses that had already been fixed. That pulls averages slightly down rather than up.
4. The record spans forty years. Tests run from October 1986 to June 2026, across charcoal canisters, continuous monitors, liquid scintillation and electret detectors. Methods and practice changed over that period.

None of this makes the figures useless. It makes them what they are: a very large, imperfect, real measurement of the ground under York County, which is a great deal more than a predicted zone.

Why the risk maps are not enough

The EPA county map places York County in Zone 1, its highest predicted category. That is correct and it is also nearly useless on its own, because Zone 1 covers a large share of Pennsylvania and says nothing about the difference between 25.06 and 2.83 pCi/L inside one county.

Live monitor maps have the opposite problem. They show real readings from real devices, but from whichever handful of monitors happen to be nearby and switched on, which is a sample of a few rather than thousands. Several of the national pages ranking for York radon queries carry no York figure at all, only a state median.

The figures here come from the same place the state uses: certified test results reported to DEP by the laboratories and testers who ran them.

What to do with your own reading

If you already have a test result, compare it with the action level rather than with your ZIP code. Four pCi/L is the number that triggers action, and it applies to your house regardless of what the neighbourhood averages.

If you do not have a result yet, that is the only real next step, and a short term test kit is the cheapest way to get one. Whatever this page says about your area, the reading that matters is the one from your own basement.

If you are buying or selling in York County, an elevated reading is normally settled with a credit rather than a cancelled sale, and the page on buying or selling a house with radon covers how that works.

If your result is at or above 4, the pages on how a radon mitigation system works and what mitigation costs in York County cover what happens next, and the list of certified York County contractors covers who can do it.

Common questions about radon levels in York County