Champaign County, IL radon potential

Champaign County is mapped as Zone 1 - Highest Potential by EPA — meaning the county-wide average indoor level is predicted above 4 pCi/L. Nationally, Champaign County ranks higher in radon potential than 97% of rated counties (the 97th percentile).

Where Champaign County sits nationally

Champaign County, Illinois is home to about 212,374 people across 996.104 square miles. Averaged across its land area, Champaign County runs about 213 people per square mile. Within its own EPA zone, Champaign County is bigger by population than 91% of the counties that share it. Geologically, Champaign County is grouped into EPA Region 5 alongside 523 other counties that share its rock and soil setting.

Zone vs. an actual test

Outdoor air nationally averages about 0.4 pCi/L, indoor air about 1.3 pCi/L — Champaign County's Zone 1 prediction clears both of those and EPA's fix-it threshold besides. EPA's guidance doesn't change because of a Zone 1 label: test the house. What changes is the reason to not put it off in Champaign County specifically.

If Champaign County tests above the action level

A short-term test kit is the standard first step and typically costs far less than mitigation itself. If a test comes back at or above 4 pCi/L, a radon mitigation system for a typical home runs roughly $800–$2,500 (around $1,200 for a common single-family install), driven mainly by foundation type, not by county.

Find Illinois's state radon program

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

Where Champaign County's figures come from

Champaign 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.