Radon Levels in Chicagoland: What Homebuyers Need to Know

Radon is the second leading cause of lung cancer in the United States, according to the U.S. Environmental Protection Agency. It's an odorless, colorless radioactive gas that rises from soil and concentrates inside homes - and Chicagoland sits in one of the most radon-prone regions in the country.

How Bad Is Radon in the Chicago Area?

The Illinois Emergency Management Agency classifies the following counties as Zone 1 (highest risk), meaning predicted average indoor radon levels exceed the EPA action level of 4.0 pCi/L:

• DuPage County
• Kane County
• Kendall County
• Will County (most areas)
• Lake County
• McHenry County

Cook County is classified as Zone 2 (moderate), but elevated readings are routinely found here too - particularly in homes with finished basements or those built on clay soils.

What Counts as a "High" Radon Reading?

The EPA action level is 4.0 picocuries per liter (pCi/L). At or above that level, mitigation is recommended. Between 2.0 and 4.0 pCi/L is considered elevated and worth monitoring. Many Chicago-area homes test in the 5-10 pCi/L range; some basements come back as high as 20-40 pCi/L.

How Radon Testing Works

Castle uses certified continuous radon monitors placed in the lowest livable level of the home for a minimum of 48 hours. Continuous monitors are more accurate than charcoal canisters because they record hourly readings and detect any tampering with windows or doors during the test.

What If My Home Tests High?

Radon mitigation is straightforward and effective. A licensed mitigation contractor installs a sub-slab depressurization system - essentially a vent pipe and a small fan that pulls radon out from under the foundation before it can enter the home. Typical installation is relatively affordable compared with long-term health risk and reduces radon levels by over 90%.

If you're buying a home in Chicagoland, add a radon test to your inspection. It's one of the highest-value forms of protection you can add. Learn more about our radon testing service.