Radon levels in Illinois

Verified county-level radon indicators are available for 102 Illinois counties. Select a county for its source period and sample details.

High results are most common in Stark County (80%) and least common in Williamson County (13%)Share of tests at or above 4 pCi/L by county · Radon test results from laboratories, 2008–2017 · 102 of 102 counties have data
Adams County: 55% of tests at or above 4 pCi/L · 3,677 testsAlexander County: 22% of tests at or above 4 pCi/L · 9 testsBond County: 44% of tests at or above 4 pCi/L · 86 testsBoone County: 48% of tests at or above 4 pCi/L · 297 testsBrown County: 38% of tests at or above 4 pCi/L · 37 testsBureau County: 58% of tests at or above 4 pCi/L · 292 testsCalhoun County: 67% of tests at or above 4 pCi/L · 6 testsCarroll County: 61% of tests at or above 4 pCi/L · 431 testsCass County: 38% of tests at or above 4 pCi/L · 52 testsChampaign County: 50% of tests at or above 4 pCi/L · 8,593 testsChristian County: 46% of tests at or above 4 pCi/L · 231 testsClark County: 22% of tests at or above 4 pCi/L · 77 testsClay County: 15% of tests at or above 4 pCi/L · 68 testsClinton County: 36% of tests at or above 4 pCi/L · 272 testsColes County: 39% of tests at or above 4 pCi/L · 295 testsCook County: 20% of tests at or above 4 pCi/L · 14,199 testsCrawford County: 19% of tests at or above 4 pCi/L · 181 testsCumberland County: 22% of tests at or above 4 pCi/L · 55 testsDeKalb County: 46% of tests at or above 4 pCi/L · 1,902 testsDe Witt County: 61% of tests at or above 4 pCi/L · 142 testsDouglas County: 43% of tests at or above 4 pCi/L · 234 testsDuPage County: 37% of tests at or above 4 pCi/L · 6,130 testsEdgar County: 38% of tests at or above 4 pCi/L · 116 testsEdwards County: 21% of tests at or above 4 pCi/L · 19 testsEffingham County: 38% of tests at or above 4 pCi/L · 763 testsFayette County: 33% of tests at or above 4 pCi/L · 133 testsFord County: 42% of tests at or above 4 pCi/L · 251 testsFranklin County: 20% of tests at or above 4 pCi/L · 199 testsFulton County: 64% of tests at or above 4 pCi/L · 329 testsGallatin County: 33% of tests at or above 4 pCi/L · 6 testsGreene County: 43% of tests at or above 4 pCi/L · 21 testsGrundy County: 41% of tests at or above 4 pCi/L · 342 testsHamilton County: 23% of tests at or above 4 pCi/L · 30 testsHancock County: 44% of tests at or above 4 pCi/L · 177 testsHardin County: 22% of tests at or above 4 pCi/L · 9 testsHenderson County: 68% of tests at or above 4 pCi/L · 38 testsHenry County: 60% of tests at or above 4 pCi/L · 1,376 testsIroquois County: 28% of tests at or above 4 pCi/L · 410 testsJackson County: 28% of tests at or above 4 pCi/L · 492 testsJasper County: 24% of tests at or above 4 pCi/L · 76 testsJefferson County: 22% of tests at or above 4 pCi/L · 320 testsJersey County: 39% of tests at or above 4 pCi/L · 90 testsJo Daviess County: 57% of tests at or above 4 pCi/L · 985 testsJohnson County: 15% of tests at or above 4 pCi/L · 48 testsKane County: 44% of tests at or above 4 pCi/L · 3,885 testsKankakee County: 42% of tests at or above 4 pCi/L · 379 testsKendall County: 47% of tests at or above 4 pCi/L · 1,128 testsKnox County: 66% of tests at or above 4 pCi/L · 853 testsLake County: 30% of tests at or above 4 pCi/L · 6,751 testsLaSalle County: 52% of tests at or above 4 pCi/L · 863 testsLawrence County: 19% of tests at or above 4 pCi/L · 48 testsLee County: 42% of tests at or above 4 pCi/L · 203 testsLivingston County: 61% of tests at or above 4 pCi/L · 215 testsLogan County: 62% of tests at or above 4 pCi/L · 390 testsMcDonough County: 54% of tests at or above 4 pCi/L · 720 testsMcHenry County: 42% of tests at or above 4 pCi/L · 2,777 testsMcLean County: 53% of tests at or above 4 pCi/L · 4,693 testsMacon County: 44% of tests at or above 4 pCi/L · 744 testsMacoupin County: 35% of tests at or above 4 pCi/L · 187 testsMadison County: 37% of tests at or above 4 pCi/L · 3,343 testsMarion County: 21% of tests at or above 4 pCi/L · 364 testsMarshall County: 64% of tests at or above 4 pCi/L · 205 testsMason County: 43% of tests at or above 4 pCi/L · 102 testsMassac County: 15% of tests at or above 4 pCi/L · 33 testsMenard County: 51% of tests at or above 4 pCi/L · 117 testsMercer County: 67% of tests at or above 4 pCi/L · 343 testsMonroe County: 44% of tests at or above 4 pCi/L · 1,021 testsMontgomery County: 37% of tests at or above 4 pCi/L · 236 testsMorgan County: 64% of tests at or above 4 pCi/L · 169 testsMoultrie County: 48% of tests at or above 4 pCi/L · 69 testsOgle County: 63% of tests at or above 4 pCi/L · 816 testsPeoria County: 50% of tests at or above 4 pCi/L · 6,543 testsPerry County: 28% of tests at or above 4 pCi/L · 177 testsPiatt County: 52% of tests at or above 4 pCi/L · 590 testsPike County: 46% of tests at or above 4 pCi/L · 108 testsPope County: 0% of tests at or above 4 pCi/L · 7 testsPulaski County: 18% of tests at or above 4 pCi/L · 11 testsPutnam County: 61% of tests at or above 4 pCi/L · 61 testsRandolph County: 40% of tests at or above 4 pCi/L · 134 testsRichland County: 19% of tests at or above 4 pCi/L · 148 testsRock Island County: 48% of tests at or above 4 pCi/L · 3,736 testsSt. Clair County: 44% of tests at or above 4 pCi/L · 2,771 testsSaline County: 21% of tests at or above 4 pCi/L · 82 testsSangamon County: 52% of tests at or above 4 pCi/L · 2,962 testsSchuyler County: 44% of tests at or above 4 pCi/L · 41 testsScott County: 50% of tests at or above 4 pCi/L · 12 testsShelby County: 57% of tests at or above 4 pCi/L · 113 testsStark County: 80% of tests at or above 4 pCi/L · 87 testsStephenson County: 63% of tests at or above 4 pCi/L · 1,217 testsTazewell County: 60% of tests at or above 4 pCi/L · 5,010 testsUnion County: 25% of tests at or above 4 pCi/L · 87 testsVermilion County: 49% of tests at or above 4 pCi/L · 379 testsWabash County: 32% of tests at or above 4 pCi/L · 34 testsWarren County: 75% of tests at or above 4 pCi/L · 304 testsWashington County: 27% of tests at or above 4 pCi/L · 132 testsWayne County: 15% of tests at or above 4 pCi/L · 86 testsWhite County: 29% of tests at or above 4 pCi/L · 34 testsWhiteside County: 47% of tests at or above 4 pCi/L · 641 testsWill County: 43% of tests at or above 4 pCi/L · 5,578 testsWilliamson County: 13% of tests at or above 4 pCi/L · 601 testsWinnebago County: 44% of tests at or above 4 pCi/L · 1,549 testsWoodford County: 62% of tests at or above 4 pCi/L · 1,524 tests
  • Under 10%
  • 10–20%
  • 20–30%
  • 30–40%
  • 40% or more
  • No data

Counties

CountyTests% ≥ 4 pCi/LMedian (pCi/L)EPA zone (1993)Source
Adams County3,67755%4.5Zone 1Radon test results from laboratories through 2017
Alexander County922%2.4Zone 3Radon test results from laboratories through 2017
Bond County8644%3.3Zone 2Radon test results from laboratories through 2017
Boone County29748%3.6Zone 1Radon test results from laboratories through 2017
Brown County3738%2.9Zone 1Radon test results from laboratories through 2017
Bureau County29258%4.6Zone 1Radon test results from laboratories through 2017
Calhoun County667%4.5Zone 1Radon test results from laboratories through 2017
Carroll County43161%5.1Zone 1Radon test results from laboratories through 2017
Cass County5238%3.0Zone 1Radon test results from laboratories through 2017
Champaign County8,59350%4.0Zone 1Radon test results from laboratories through 2017
Christian County23146%3.7Zone 2Radon test results from laboratories through 2017
Clark County7722%2.0Zone 2Radon test results from laboratories through 2017
Clay County6815%1.1Zone 2Radon test results from laboratories through 2017
Clinton County27236%2.8Zone 2Radon test results from laboratories through 2017
Coles County29539%3.1Zone 1Radon test results from laboratories through 2017
Cook County14,19920%1.8Zone 2Radon test results from laboratories through 2017
Crawford County18119%1.8Zone 2Radon test results from laboratories through 2017
Cumberland County5522%1.8Zone 2Radon test results from laboratories through 2017
De Witt County14261%4.8Zone 1Radon test results from laboratories through 2017
DeKalb County1,90246%3.6Zone 1Radon test results from laboratories through 2017
Douglas County23443%3.4Zone 1Radon test results from laboratories through 2017
DuPage County6,13037%2.9Zone 2Radon test results from laboratories through 2017
Edgar County11638%3.2Zone 1Radon test results from laboratories through 2017
Edwards County1921%2.1Zone 2Radon test results from laboratories through 2017
Effingham County76338%3.0Zone 2Radon test results from laboratories through 2017
Fayette County13333%2.7Zone 2Radon test results from laboratories through 2017
Ford County25142%3.4Zone 1Radon test results from laboratories through 2017
Franklin County19920%1.8Zone 2Radon test results from laboratories through 2017
Fulton County32964%5.4Zone 1Radon test results from laboratories through 2017
Gallatin County633%2.0Zone 2Radon test results from laboratories through 2017
Greene County2143%3.5Zone 1Radon test results from laboratories through 2017
Grundy County34241%3.1Zone 1Radon test results from laboratories through 2017
Hamilton County3023%1.9Zone 2Radon test results from laboratories through 2017
Hancock County17744%3.5Zone 1Radon test results from laboratories through 2017
Hardin County922%1.4Zone 2Radon test results from laboratories through 2017
Henderson County3868%5.7Zone 1Radon test results from laboratories through 2017
Henry County1,37660%4.9Zone 1Radon test results from laboratories through 2017
Iroquois County41028%2.1Zone 1Radon test results from laboratories through 2017
Jackson County49228%2.3Zone 2Radon test results from laboratories through 2017
Jasper County7624%1.9Zone 2Radon test results from laboratories through 2017
Jefferson County32022%1.9Zone 2Radon test results from laboratories through 2017
Jersey County9039%3.2Zone 1Radon test results from laboratories through 2017
Jo Daviess County98557%4.6Zone 1Radon test results from laboratories through 2017
Johnson County4815%1.8Zone 2Radon test results from laboratories through 2017
Kane County3,88544%3.4Zone 1Radon test results from laboratories through 2017
Kankakee County37942%3.3Zone 2Radon test results from laboratories through 2017
Kendall County1,12847%3.6Zone 1Radon test results from laboratories through 2017
Knox County85366%6.1Zone 1Radon test results from laboratories through 2017
LaSalle County86352%4.1Zone 1Radon test results from laboratories through 2017
Lake County6,75130%2.5Zone 2Radon test results from laboratories through 2017
Lawrence County4819%1.8Zone 2Radon test results from laboratories through 2017
Lee County20342%3.3Zone 1Radon test results from laboratories through 2017
Livingston County21561%5.7Zone 1Radon test results from laboratories through 2017
Logan County39062%5.3Zone 1Radon test results from laboratories through 2017
Macon County74444%3.4Zone 1Radon test results from laboratories through 2017
Macoupin County18735%2.7Zone 2Radon test results from laboratories through 2017
Madison County3,34337%3.0Zone 2Radon test results from laboratories through 2017
Marion County36421%1.7Zone 2Radon test results from laboratories through 2017
Marshall County20564%6.0Zone 1Radon test results from laboratories through 2017
Mason County10243%3.5Zone 1Radon test results from laboratories through 2017
Massac County3315%1.9Zone 3Radon test results from laboratories through 2017
McDonough County72054%4.5Zone 1Radon test results from laboratories through 2017
McHenry County2,77742%3.2Zone 2Radon test results from laboratories through 2017
McLean County4,69353%4.3Zone 1Radon test results from laboratories through 2017
Menard County11751%4.2Zone 1Radon test results from laboratories through 2017
Mercer County34367%6.8Zone 1Radon test results from laboratories through 2017
Monroe County1,02144%3.5Zone 2Radon test results from laboratories through 2017
Montgomery County23637%2.8Zone 2Radon test results from laboratories through 2017
Morgan County16964%5.8Zone 1Radon test results from laboratories through 2017
Moultrie County6948%3.8Zone 1Radon test results from laboratories through 2017
Ogle County81663%5.5Zone 1Radon test results from laboratories through 2017
Peoria County6,54350%4.0Zone 1Radon test results from laboratories through 2017
Perry County17728%2.4Zone 2Radon test results from laboratories through 2017
Piatt County59052%4.0Zone 1Radon test results from laboratories through 2017
Pike County10846%3.8Zone 1Radon test results from laboratories through 2017
Pope County70%1.8Zone 2Radon test results from laboratories through 2017
Pulaski County1118%2.0Zone 3Radon test results from laboratories through 2017
Putnam County6161%5.4Zone 1Radon test results from laboratories through 2017
Randolph County13440%3.2Zone 2Radon test results from laboratories through 2017
Richland County14819%1.8Zone 2Radon test results from laboratories through 2017
Rock Island County3,73648%3.8Zone 1Radon test results from laboratories through 2017
Saline County8221%1.7Zone 2Radon test results from laboratories through 2017
Sangamon County2,96252%4.2Zone 1Radon test results from laboratories through 2017
Schuyler County4144%3.8Zone 1Radon test results from laboratories through 2017
Scott County1250%4.4Zone 1Radon test results from laboratories through 2017
Shelby County11357%4.4Zone 2Radon test results from laboratories through 2017
St. Clair County2,77144%3.5Zone 2Radon test results from laboratories through 2017
Stark County8780%7.4Zone 1Radon test results from laboratories through 2017
Stephenson County1,21763%5.3Zone 1Radon test results from laboratories through 2017
Tazewell County5,01060%5.1Zone 1Radon test results from laboratories through 2017
Union County8725%1.9Zone 2Radon test results from laboratories through 2017
Vermilion County37949%3.8Zone 1Radon test results from laboratories through 2017
Wabash County3432%3.0Zone 2Radon test results from laboratories through 2017
Warren County30475%7.1Zone 1Radon test results from laboratories through 2017
Washington County13227%2.6Zone 2Radon test results from laboratories through 2017
Wayne County8615%1.4Zone 2Radon test results from laboratories through 2017
White County3429%2.9Zone 2Radon test results from laboratories through 2017
Whiteside County64147%3.7Zone 1Radon test results from laboratories through 2017
Will County5,57843%3.4Zone 2Radon test results from laboratories through 2017
Williamson County60113%1.3Zone 2Radon test results from laboratories through 2017
Winnebago County1,54944%3.4Zone 1Radon test results from laboratories through 2017
Woodford County1,52462%5.2Zone 1Radon test results from laboratories through 2017

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