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

EPA's own radon map rates Macon County zone 1 - highest potential, predicting a county-wide average indoor level above 4 pCi/L. Rank it against the rest of the country and Macon County lands in the 94th percentile for radon potential.

How Macon County compares

Macon County, Illinois is home to about 100,737 people across 580.548 square miles. Population density there runs about 174 people per square mile. By population, Macon County is the 194th largest of every county sharing its EPA zone — the 82nd percentile by population within that zone. EPA's geology-based Region 5 groups Macon County with 523 other counties nationally sharing its underlying rock and soil profile.

What this actually means for a house in Macon County

Outdoor air nationally averages about 0.4 pCi/L, indoor air about 1.3 pCi/L — Macon County's Zone 1 prediction clears both of those and EPA's fix-it threshold besides. Some Macon County homes will test comfortably under the action level despite the county's Zone 1 rating — the only way to know which kind of home you have is an actual test.

Testing and mitigation in Macon County

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

Where Macon County's figures come from

Every figure on this page traces to EPA's own Map of Radon Zones and Census data, documented in the methodology guide. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.