What Is Radon and How Does It Enter Peoria Homes?
Radon is a colorless, odorless, radioactive gas produced by the natural breakdown of uranium in soil and rock. It occurs at some concentration almost everywhere, and it becomes a health concern specifically when it accumulates indoors rather than dispersing outside.
Radon moves from the ground into a home whenever indoor air pressure is lower than the pressure in the soil beneath the foundation — a condition present in nearly every house. Much of the Peoria area sits on glacial till, soil deposited by retreating glaciers thousands of years ago, which can carry higher concentrations of uranium-bearing minerals than soil in other parts of the state. This geology is a major reason radon readings run high across central Illinois.
- Cracks in the foundation slab or basement walls
- Openings around sump pump pits
- Exposed dirt or gaps in crawlspaces
- Floor drains connected to the soil beneath the home
- Gaps around pipes and utility penetrations
Is the Radon Risk High in Peoria and Illinois?
Illinois has one of the highest baseline radon profiles of any state. Data compiled by the Illinois Emergency Management Agency (IEMA) and the Illinois Department of Public Health (IDPH) shows that a large share of homes tested statewide, and in central Illinois specifically, exceed the U.S. Environmental Protection Agency's action level. Professional radon testing in Peoria IL is the only reliable way to know where a specific property falls, since radon levels can vary significantly between neighboring homes and even between floors of the same house.
Health Risks and Safe Thresholds (EPA Guidelines)
The EPA sets its action level at 4.0 pCi/L: at or above this reading, the agency recommends fixing the home. The World Health Organization uses a more conservative reference level of 2.7 pCi/L. Neither figure represents a fully safe threshold — no level of radon exposure is considered completely risk-free, and risk increases with both concentration and duration of exposure. Radon is the second leading cause of lung cancer in the United States, after smoking, and the leading cause among non-smokers.
Average Radon Levels by County: Peoria & Tazewell Statistics
The EPA groups counties into radon potential zones, with Zone 1 representing the highest predicted average indoor levels. As illustrated on the official peoria radon map and regional hazard charts, both Peoria and Tazewell counties fall into Zone 1. This means homes in this region have a statistically higher likelihood of testing above the EPA action level than homes in Zone 2 or Zone 3 areas.
| County | EPA Radon Zone | Average Measurement (pCi/L) | Action Level | Recommended Action |
|---|---|---|---|---|
| Peoria County | Zone 1 (High Risk) | 6.9 pCi/L | 4.0 pCi/L | Active Mitigation Recommended |
| Tazewell County | Zone 1 (High Risk) | 5.8 pCi/L | 4.0 pCi/L | Active Mitigation Recommended |
| Illinois State (Avg) | Zone 1/2 | 4.4 pCi/L | 4.0 pCi/L | Testing & Mitigation if elevated |
Active Mitigation Recommended
Active Mitigation Recommended
Testing & Mitigation if elevated
Regional Radon Levels and EPA Zone Classifications
The Peoria tri-county area's Zone 1 designation traces back to the region's glacial geology. Glacial deposits left behind by retreating ice sheets contain shale and granite fragments with naturally higher concentrations of uranium than the surrounding soil, which decays into radon gas over time. This geological pattern, rather than anything about individual home construction, is the primary driver behind the elevated county averages shown above.
What Should Your Radon Levels Be After Mitigation?
A properly installed radon mitigation system — typically an active or passive sub-slab depressurization system — is designed to pull indoor radon concentrations well below the EPA action level. In most Peoria-area homes, a correctly functioning system should bring indoor readings down below 2.0 pCi/L, and often closer to the natural outdoor ambient average of roughly 0.4 pCi/L.
Post-installation testing is the only way to confirm a certified radon mitigation system is performing as intended. Fan performance, system sealing, and seasonal pressure changes can all affect results, which is why a follow-up test is standard practice after installation.
How and When to Test Your Home for Radon in Peoria, IL
Testing is the only way to know a specific home's radon level, since readings vary by foundation type, soil conditions, and even weather. Testing is especially important during real estate transactions, after major renovations that alter the foundation or ventilation, or at a minimum of once every two years for homes that have not been previously mitigated.
Where to Get a Radon Test Kit in Peoria County
Short-term test kits are available through some local hardware stores and, in some cases, through the Peoria City/County Health Department. For a more precise reading, or when a result will be used for a real estate transaction, booking professional radon testing in Peoria IL with a certified technician is the more reliable option.
Understanding Real Estate Radon Disclosures in Illinois
Illinois law addresses radon directly through the Illinois Radon Awareness Act. Under this law, home sellers are required to disclose any known radon hazards to prospective buyers as part of the standard disclosure process, making a documented test result a practical asset during a home sale.
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Common Questions About Peoria Radon
What is considered a safe radon level for a home in Peoria?
The EPA action level is 4.0 pCi/L, and the agency recommends fixing any home at or above that reading. The WHO uses a more conservative reference level of 2.7 pCi/L. No level is considered entirely risk-free.
How often should I test for radon in Illinois?
At minimum, every two years for homes that haven't been mitigated, and again after any major renovation that affects the foundation or ventilation, or before a real estate transaction.
Do I have to disclose radon test results when selling my home in Illinois?
Yes. The Illinois Radon Awareness Act requires sellers to disclose known radon hazards to buyers as part of the standard disclosure process.
Will a mitigation system bring my home below the EPA action level?
A properly installed and functioning sub-slab depressurization system typically brings indoor levels below 2.0 pCi/L, well under the 4.0 pCi/L action level. Post-installation testing confirms actual performance.
Why are Peoria and Tazewell counties considered high-risk for radon?
Both counties fall into EPA Zone 1 due to glacial till soil containing higher concentrations of uranium-bearing minerals, which is the primary driver behind the region's elevated average readings.