Is radon high in Cumberland County?

61% of 4,713 home tests reported to the CDC came back at or above the EPA action level of 4 pCi/L — 12 points above the Pennsylvania county median of 49%, ranking #11 of 67 tested counties. EPA classifies the county as Zone 1.

Does an older home in Cumberland County mean more radon risk?

The county's median home was built in 1978 — 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 Cumberland County numbers come from?

4,713 aggregated home tests in the CDC's Environmental Public Health Tracking dataset (CDC EPHT 2008-2017). Median reading: 5.8 pCi/L; the highest recorded test hit 206.6 pCi/L. How we handle the data, including its limits, is documented on our methodology page.

Which ZIP codes in Cumberland County test highest?

In PA DEP's residential results (1986–2026): 17011 (Camp Hill) — 60.8% of 288 tests over the limit; 17027 (Grantham) — 55.8% of 43 tests over the limit; 17324 (Gardners) — 55.7% of 70 tests over the limit. Full ZIP table below.

Pennsylvania · county radon data

Radon in Cumberland County, Pennsylvania

61% of the 4,713 home radon tests on record here reached the EPA action level — among the higher-testing counties in the state, ranked #11 of 67 tested Pennsylvania counties.

Cumberland, PA

61%

Tests at or above 4 pCi/L

5.8 pCi/L

Median reading

206.6 pCi/L

Highest recorded

Based on 4,713 tests · CDC EPHT (labs), 2008–2017 · how we know

What the numbers say

Cumberland County sits 12 points above the Pennsylvania median (49% of tests over the limit across the state's counties). The median reading among its 4,713 reported tests was 5.8 pCi/L — and the single highest test on record reached 206.6 pCi/L, more than 51× 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 Cumberland 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 Cumberland County home dates to 1978 — decades before radon-resistant new construction entered building codes. With 268,323 residents largely housed in that older stock, testing is the only way any individual household knows where it stands.

Radon by ZIP in Cumberland 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
17011	Camp Hill	288	60.8%	97.7
17027	Grantham	43	55.8%	52.4
17324	Gardners	70	55.7%	106.7
17240	Newburg	165	55.2%	76.8
17015	Carlisle	3,010	52.8%	209
17013	Carlisle	6,887	52.7%	350
17050	Mechanicsburg	7,889	51.2%	4816
17043	Lemoyne	793	50.9%	90.9
17007	Boiling Springs	1,301	50.7%	183
17257	Shippensburg	1,901	50%	231.2
17025	Enola	2,358	48.1%	173
17065	Mount Holly Springs	532	47%	55.4
17266	Walnut Bottom	56	46.4%	19.6
17241	Newville	1,787	41.1%	272.6
17055	Mechanicsburg	65	40%	176.1
17093	Summerdale	30	40%	22.2

Cumberland County in the Pennsylvania picture

Cumberland County	61% over the limit	4,713 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	2.7%

Ranked nearby in Pennsylvania

Union County — #8, 62.9% of 320 tests over the limit
Perry County — #9, 62.5% of 548 tests over the limit
Montour County — #10, 61.6% of 165 tests over the limit
York County — #12, 59.7% of 7,893 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

(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).

Cumberland County radon FAQ

Is radon high in Cumberland County?: 61% of 4,713 home tests reported to the CDC came back at or above the EPA action level of 4 pCi/L — 12 points above the Pennsylvania county median of 49%, ranking #11 of 67 tested counties. EPA classifies the county as Zone 1.
Does an older home in Cumberland County mean more radon risk?: The county's median home was built in 1978 — 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 Cumberland County numbers come from?: 4,713 aggregated home tests in the CDC's Environmental Public Health Tracking dataset (CDC EPHT 2008-2017). Median reading: 5.8 pCi/L; the highest recorded test hit 206.6 pCi/L. How we handle the data, including its limits, is documented on our methodology page.
Which ZIP codes in Cumberland County test highest?: In PA DEP's residential results (1986–2026): 17011 (Camp Hill) — 60.8% of 288 tests over the limit; 17027 (Grantham) — 55.8% of 43 tests over the limit; 17324 (Gardners) — 55.7% of 70 tests over the limit. Full ZIP table below.