Radon in Illinois

Illinois Map of Radon Zones

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Illinois Map of Radon Zones

Zone 1: High Potential

Zone 2: Moderate Potential

Zone 3: Low Potential

The Environmental Protection Agency (EPA) publishes a nationwide map of radon zones to indicate the potential concentrations of homes with elevated radon levels in a geographic region. According to the Illinois Map of Radon Zones, the central and northern half of the state, including McLean County, lies in Zone 1, the highest potential zone for radon problems. The counties along the northeastern border of the state in the southern half of the state lie within Zone 2, which has a moderate potential for radon problems.

An Illinois Emergency Management Agency (IEMA) study of the results from nearly 72,000 home radon tests from 2003-2007 reveals that nearly half of the homes tested in Illinois had elevated levels of radon (that is, levels greater than the USEPA action level of 4 pCi/L). More than 50% of the homes tested positive for elevated levels of radon in twenty-four counties. In thirty-four other counties, 25-50% of the homes tested positive.

No matter where you live, you should still test your home for radon. Even if you live in a low potential zone, your home could still have a radon problem.

Counties where more than 50% of tested homes had elevated radon levels:

  • Adams
  • Caroll
  • Champaign
  • DeWitt
  • Fulton
  • Henry
  • Jo Daviess
  • Knox
  • Livingston
  • Marshall
  • McLean
  • Mercer
  • Morgan
  • Ogle
  • Peoria
  • Piatt
  • Rock Island
  • Sangamon
  • Stark
  • Stephenson
  • Tazewell
  • Warren
  • Whiteside
  • Woodford

Counties where 25-50% of tested homes had elevated radon levels:

  • Boone
  • Bureau
  • Christian
  • Clark
  • Clinton
  • Coles
  • Cook
  • DeKalb
  • DuPage
  • Edgar
  • Effingham
  • Grundy
  • Iroquois
  • Kane
  • Kankakee
  • Kendall
  • Lake
  • LaSalle
  • Lee
  • Logan
  • Macon
  • Macoupin
  • Madison
  • McDonough
  • McHenry
  • Menard
  • Monroe
  • Montgomery
  • Moultrie
  • Shelby
  • St. Clair
  • Union
  • Will
  • Winnebago

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