Cass County, IL: Radon Risk Data
EPA predicts average indoor levels above 4 pCi/L · Source: EPA, CDC
Tipper's take on Cass County
Cass County is in EPA Zone 1, the highest risk classification. The EPA's geological and indoor measurement data predicts average indoor radon levels above 4 pCi/L here, which is the agency's action level. CDC testing data from Cass County puts the average measured radon level at 4.5 pCi/L.
Zone 1 doesn't mean every home is over the limit. Radon varies house to house depending on foundation type, construction, soil, and ventilation. A well-sealed Zone 1 home might test at 2 pCi/L. A cracked basement in a Zone 3 county might test at 9 pCi/L. The zone tells you about area-level risk. Your test result tells you about your home.
Zone 1 is a meaningful signal, though. If you live in Cass County and haven't tested, you should. A basic test kit runs about $15 and gives you a result in 48 hours.
Sources: EPA Radon Zone Map, CDC Environmental Public Health Tracking Network
Test Your Home
The only way to know your home's radon level is to test it. Tipper recommends starting with a short-term test kit. It includes the lab fee, takes 48 hours, and costs about $15.
Radon Professionals Serving Illinois
No contractors in our directory are listed specifically for Cass County. These certified pros serve Illinois and may cover your area. Call to confirm.
How Cass County Compares
vs. Illinois Statewide
Cass County's average of 4.5 pCi/L is 0.5 pCi/L below the statewide average.
Frequently Asked Questions: Cass County
My home is in Zone 1. Does that mean it's definitely dangerous?
Not automatically. Zone 1 means the EPA expects area-wide average indoor levels above 4 pCi/L. That's an average across many homes with different foundations, construction types, and ventilation. A well-sealed Zone 1 home on a concrete slab might test at 1.5 pCi/L. Test first, then decide. The zone tells you to take it seriously. Your test result tells you what to do.
What is the EPA's action level, and why 4 pCi/L?
The EPA recommends fixing your home if it tests at or above 4 pCi/L (picocuries per liter). There's no completely safe level. Radon exposure is a spectrum. But 4 pCi/L is where the EPA concludes mitigation is clearly cost-effective. The WHO sets a lower reference level of 2.7 pCi/L. If your home is between 2 and 4 pCi/L, mitigation is optional but worth considering, especially in bedrooms.
How often should I retest for radon?
If your home tested below 4 pCi/L and nothing major has changed structurally, retesting every two years is a good habit. Retest immediately after any significant basement renovation, after buying or selling a home, or after installing a mitigation system (to confirm it's working). Radon levels can shift as foundations settle and conditions change.
The county average is above 4 pCi/L. Should I be worried about my kids?
Children's lungs are still developing, and they typically spend more time at home, so radon exposure matters for them. The county average above 4 pCi/L doesn't mean your home is above that level, though. Test your specific home. If it comes back high, a mitigation system typically brings levels below 2 pCi/L. That's the right response.