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Radon zones in Pennsylvania

The EPA assigns every county in Pennsylvania to one of three radon potential zones. 49 are in Zone 1, the highest category, home to about 77% of the state's residents.

67
Counties
49
Zone 1 counties
Predicted average above 4 pCi/L
17
Zone 2 counties
Predicted average 2-4 pCi/L
1
Zone 3 counties
Predicted average below 2 pCi/L

The map

Radon potential across Pennsylvania

Every county in Pennsylvania, filled by the zone the EPA assigns it. Zones follow geology rather than county lines, so the colour usually changes where the bedrock does, not where the border is.

Zone 1 · 49Zone 2 · 17Zone 3 · 1

Hover a county · click to open it

County by county

All 67 Pennsylvania counties

Zone 1 · > 4 pCi/LZone 2 · 2 - 4 pCi/LZone 3 · < 2 pCi/L
CountyZonePopulationCOPDSmokingLung ca. deaths
Adams County1106k7.7%15.7%32.5
Allegheny County11.2M7.2%14.7%33.8
Armstrong County165k9.8%19.6%40.3
Beaver County1166k8.4%15.5%37.5
Bedford County147k9.9%18.2%32.4
Berks County1430k7.5%14.8%31.4
Blair County1121k10.2%19.2%38.2
Bradford County160k9.0%16.1%34.1
Bucks County1645k7.6%15.5%28.9
Butler County1197k6.2%12.2%30.6
Cameron County14,41812.3%20.8% -
Carbon County165k9.3%17.6%35.4
Centre County1158k6.5%15.1%23.6
Chester County1546k5.1%10.6%26.1
Clarion County137k8.9%18.0%37.8
Clearfield County178k10.6%20.0%34.7
Clinton County138k8.6%18.4%32.7
Columbia County165k8.5%16.4%30.5
Cumberland County1269k6.9%14.1%30.7
Dauphin County1289k7.9%17.1%30.4
Delaware County1575k5.5%12.5%33.7
Franklin County1157k8.3%18.5%35.0
Fulton County115k8.6%17.2%46.7
Huntingdon County143k8.4%18.8%34.0
Indiana County183k8.2%15.4%27.0
Juniata County123k9.6%18.8%34.8
Lackawanna County1216k8.1%16.5%38.1
Lancaster County1557k7.3%15.2%27.6
Lebanon County1144k7.7%15.2%34.2
Lehigh County1376k7.2%16.0%30.0
Luzerne County1326k8.5%17.5%38.5
Lycoming County1113k8.5%16.5%41.3
Mifflin County146k10.3%20.8%37.1
Monroe County1167k7.5%15.8%30.7
Montgomery County1865k6.6%12.5%26.8
Montour County118k8.9%16.8%37.2
Northampton County1319k6.9%14.6%29.2
Northumberland County190k9.7%19.2%37.1
Perry County146k8.7%17.8%47.0
Schuylkill County1143k9.8%19.9%43.3
Snyder County140k8.4%15.3%37.3
Sullivan County15,85511.9%21.1%24.0
Susquehanna County138k7.5%14.3%40.0
Tioga County141k10.3%18.6%36.3
Union County143k8.3%17.5%29.4
Venango County150k10.3%18.1%42.5
Westmoreland County1352k7.0%13.4%33.6
Wyoming County126k10.4%19.2%45.3
York County1461k6.5%15.7%36.4
Cambria County2131k9.7%18.1%31.5
Crawford County283k9.6%19.5%40.0
Elk County230k10.1%17.9%38.6
Erie County2268k8.5%17.8%39.0
Fayette County2126k10.7%20.7%42.9
Forest County26,62610.0%21.8%51.0
Greene County235k9.6%18.7%47.3
Jefferson County244k10.2%20.2%34.0
Lawrence County285k9.2%17.7%34.9
McKean County240k8.8%16.0%45.0
Mercer County2109k8.8%16.8%36.9
Pike County261k7.7%14.6%32.3
Potter County216k9.7%18.2%39.5
Somerset County273k9.0%18.6%30.8
Warren County238k9.7%18.5%41.7
Washington County2210k8.1%16.6%38.4
Wayne County251k10.3%18.9%43.3
Philadelphia County31.6M8.3%18.4%36.1

Zones from the EPA Map of Radon Zones. COPD and smoking are CDC PLACES model-based estimates of adult prevalence. Lung cancer death rates are age-adjusted deaths per 100,000 per year, 2019-2023, from NCI State Cancer Profiles. A dash means the source does not report a value for that county.

Highest potential

Zone 1 counties in Pennsylvania

These 49 counties have a predicted average indoor radon screening level above the EPA action level. The EPA recommends every home in them be tested.

Other states

Radon zones elsewhere