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Radon zones in Indiana

The EPA assigns every county in Indiana to one of three radon potential zones. 57 are in Zone 1, the highest category, home to about 72% of the state's residents.

92
Counties
57
Zone 1 counties
Predicted average above 4 pCi/L
35
Zone 2 counties
Predicted average 2-4 pCi/L
0
Zone 3 counties
Predicted average below 2 pCi/L

The map

Radon potential across Indiana

Every county in Indiana, 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 · 57Zone 2 · 35Zone 3 · 0

Hover a county · click to open it

County by county

All 92 Indiana counties

Zone 1 · > 4 pCi/LZone 2 · 2 - 4 pCi/LZone 3 · < 2 pCi/L
CountyZonePopulationCOPDSmokingLung ca. deaths
Adams County136k10.4%19.4%35.7
Allen County1395k7.6%14.4%36.4
Bartholomew County184k7.6%14.8%40.1
Benton County18,72910.0%18.8%57.1
Blackford County112k12.1%20.8%53.9
Boone County176k5.9%11.6%30.3
Carroll County121k9.5%17.5%40.3
Cass County138k10.0%18.5%44.3
Clark County1125k8.1%16.4%49.6
Clinton County133k8.9%17.5%40.7
Decatur County126k8.5%16.4%46.1
DeKalb County144k8.6%16.8%39.8
Delaware County1112k9.1%16.8%51.2
Elkhart County1206k8.8%17.0%36.6
Fayette County123k11.4%20.2%52.4
Fountain County117k10.0%18.5%52.2
Fulton County120k10.2%18.6%57.5
Grant County166k10.1%17.8%56.5
Hamilton County1372k4.7%9.5%23.8
Hancock County186k6.7%13.6%39.7
Harrison County140k8.7%16.2%45.9
Hendricks County1186k6.1%12.8%34.8
Henry County149k9.6%18.0%58.8
Howard County184k9.4%17.9%46.1
Huntington County137k8.8%16.6%43.7
Jay County120k11.0%20.2%44.2
Jennings County128k9.9%19.5%67.7
Johnson County1168k6.9%14.1%40.0
Kosciusko County180k8.5%16.6%40.1
LaGrange County141k9.8%19.6%38.9
Lawrence County145k9.5%16.9%52.5
Madison County1133k9.2%18.5%48.4
Marion County1968k7.3%15.0%44.7
Marshall County146k9.4%17.4%33.8
Miami County135k9.9%19.2%51.8
Monroe County1139k6.4%12.2%36.0
Montgomery County139k9.6%17.5%40.3
Noble County147k8.9%17.0%48.6
Orange County120k10.5%19.1%53.1
Putnam County138k8.3%16.4%57.5
Randolph County124k10.3%18.7%49.4
Rush County117k10.1%18.6%51.6
Scott County125k10.4%20.0%72.8
Shelby County145k9.2%17.9%48.3
St. Joseph County1273k7.8%14.9%39.0
Steuben County135k8.8%15.4%38.5
Tippecanoe County1189k6.4%13.0%39.9
Tipton County115k8.9%15.7%36.3
Union County16,9738.6%15.9%49.5
Vermillion County115k10.1%18.6%59.8
Wabash County131k9.7%16.8%41.8
Warren County18,5189.6%17.4%36.6
Washington County128k10.6%19.8%59.5
Wayne County166k10.3%19.1%44.7
Wells County129k8.5%16.4%38.1
White County125k9.5%16.4%47.1
Whitley County135k8.5%15.8%41.4
Brown County216k9.5%15.9%47.6
Clay County226k9.6%18.0%43.6
Crawford County210k13.8%23.5%44.8
Daviess County234k10.2%19.7%40.8
Dearborn County251k8.3%16.3%48.2
Dubois County244k8.5%15.4%30.7
Floyd County281k7.8%14.9%45.5
Franklin County223k9.1%16.8%39.3
Gibson County233k9.0%17.6%35.5
Greene County231k10.5%19.4%56.2
Jackson County246k8.8%17.3%43.7
Jasper County234k8.4%15.8%45.5
Jefferson County233k9.2%17.2%50.2
Knox County236k9.3%17.5%49.3
Lake County2501k8.4%17.0%34.3
LaPorte County2112k9.2%17.6%41.2
Martin County29,89710.3%18.7%50.8
Morgan County273k8.7%16.3%49.8
Newton County214k10.0%18.3%63.2
Ohio County26,0049.6%16.6%58.6
Owen County222k10.3%18.5%47.8
Parke County216k11.8%20.7%46.8
Perry County219k9.2%18.3%41.1
Pike County212k10.2%18.6%59.7
Porter County2175k7.4%14.5%37.0
Posey County225k8.5%15.3%29.4
Pulaski County212k10.2%18.3%45.9
Ripley County229k8.7%16.9%34.0
Spencer County220k8.6%16.0%37.6
Starke County223k10.9%19.9%54.7
Sullivan County221k10.3%19.9%50.8
Switzerland County210k10.9%20.4%51.7
Vanderburgh County2180k8.6%16.2%39.8
Vigo County2106k9.5%17.6%46.9
Warrick County266k6.8%13.0%39.3

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 Indiana

These 57 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