DuPage County, IL: EPA's radon zone, explained

EPA's own radon map rates DuPage County zone 2 - moderate potential, predicting a county-wide average indoor level between 2 and 4 pCi/L. DuPage County sits at the 65th percentile nationally for radon potential — above 65 of every 100 rated counties.

Where DuPage County sits nationally

DuPage County, Illinois is home to about 937,142 people across 327.892 square miles. That works out to roughly 2,858 people per square mile. By population, DuPage County is the 20th largest of every county sharing its EPA zone — the 98th percentile by population within that zone. DuPage County falls in EPA Radon Region 5, one of 524 counties nationally EPA assigns to that same geologic province.

What this actually means for a house in DuPage County

EPA's Zone 2 rating for DuPage County sits below its own 4 pCi/L action level but above the national indoor average of about 1.3 pCi/L. A Zone 2 rating is a moderate county-wide average, not a guarantee about any one house in DuPage County — testing is the only way to know an individual home's actual level.

Next steps for a home in DuPage County

For a DuPage County homeowner, the order is simple: test first, since a kit costs a small fraction of what mitigation would. Only if the result clears 4 pCi/L does a system — typically $800–$2,500, about $1,200 for a common install — become worth pricing out.

Find Illinois's state radon program

For DuPage County, an ongoing number beats a one-time test - a Airthings radon monitor tracks DuPage County's levels over time. RadonZoneCheck earns a commission there, at no extra cost to you. RADONZONE-10OFF at checkout knocks 10% off.

Where DuPage County's figures come from

DuPage County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.