Illinois has significant radon risk, with an estimated 35–40% of Illinois homes testing above the EPA action level of 4.0 pCi/L. The Illinois Emergency Management Agency (IEMA) Radon Section estimates that radon may be responsible for approximately 1,000 lung cancer deaths in Illinois annually — more deaths than are caused by drunk driving. Illinois has enacted some of the more comprehensive radon legislation in the Midwest, including contractor licensing requirements and school radon testing mandates.
EPA Radon Zone Designation
Illinois is predominantly EPA Radon Zone 1. Illinois counties range from Zone 1 in northern and central Illinois to Zone 2 in the southern portion of the state. The highest-radon areas are concentrated in the glaciated portions of northern and central Illinois where glacial till deposits overlie uranium-bearing geology. Northern Illinois counties in the Chicago metropolitan area and central Illinois agricultural counties show the highest average readings.
Radon Contractor Licensing in Illinois
Illinois has a comprehensive radon contractor licensing program. Illinois law requires radon contractors — both for measurement and for mitigation — to hold an Illinois state radon contractor license issued by the Illinois Emergency Management Agency. Illinois licensing requires passing state-approved training, holding NRPP or NRSB certification, carrying liability insurance, and paying licensing fees. Illinois maintains a searchable database of licensed radon contractors at iema.illinois.gov/radon. Performing radon measurement or mitigation without an Illinois radon license is a violation of Illinois law.
Radon Disclosure Requirements in Illinois
Illinois has enacted specific radon disclosure requirements for real estate transactions. Illinois law requires sellers of residential property to disclose known radon test results to buyers. Illinois uses a Residential Real Property Disclosure Act that includes radon — sellers must indicate whether they have received a radon test report and provide the report to buyers if one exists. Illinois also requires IEMA-approved radon pamphlets to be provided in certain transactions. Additionally, Illinois law requires radon testing in all public schools and mandates school radon disclosure to parents.
Radon-Resistant New Construction (RRNC) in Illinois
Illinois does not have a statewide RRNC mandate for new residential construction. However, the IEMA Radon Section strongly recommends RRNC for new construction in Illinois, particularly in Zone 1 northern and central counties. Some Illinois municipalities — particularly in the Chicago metropolitan area — have incorporated RRNC requirements locally. Buyers of new construction should ask about RRNC inclusion, especially in northern Illinois.
Highest-Radon Counties and Areas in Illinois
Illinois’s highest-radon areas are in the glaciated northern and central counties. The Chicago metropolitan area counties — Cook, DuPage, Kane, Lake, McHenry, Will, and Kendall — have elevated average radon levels. Central Illinois agricultural counties — including McLean, Tazewell, Peoria, Sangamon, and Champaign — also show significant radon levels. Southern Illinois counties generally have lower but still meaningful radon levels. IEMA publishes county-level radon data from the Illinois Radon Monitoring Program.
Testing Resources for Illinois Residents
The Illinois Emergency Management Agency (IEMA) Radon Section administers the state radon program and provides resources for homeowners including lists of certified contractors, low-cost or free test kit programs (availability varies by year and funding), and technical guidance on radon mitigation. Contact the state radon program directly for the most current contractor list, any available test kit distribution programs, and jurisdiction-specific requirements that may have changed since this page was last updated.
Frequently Asked Questions
Does Illinois require radon contractor licensing?
Yes. Illinois has one of the more comprehensive radon contractor licensing programs in the nation. Both measurement and mitigation contractors must hold an Illinois state radon license issued by IEMA, in addition to NRPP or NRSB national certification. Verify license status at iema.illinois.gov/radon.
Does Illinois require radon disclosure when selling a home?
Yes. Illinois law requires sellers to disclose known radon test results to buyers under the Residential Real Property Disclosure Act. If a radon test report exists, it must be provided to buyers.
Does Illinois require radon testing in schools?
Yes. Illinois law requires radon testing in all Illinois public schools. Results must be disclosed to parents. Illinois is among the states with the most comprehensive school radon testing mandates in the U.S.
Leave a Reply