Is Effingham County, IL a radon risk area?

EPA places Effingham County in Zone 2 - Moderate Potential — a predicted county-wide average indoor radon level between 2 and 4 pCi/L, based on the geology, soil and aerial radioactivity data behind EPA's national map. Nationally that's the 52nd percentile for radon potential — Effingham County outranks 52% of every county EPA has rated.

Effingham County by the numbers

About 34,602 people live in Effingham County, Illinois, spread over 478.767 square miles. Population density there runs about 72 people per square mile. Rank 444 by population within its EPA zone puts Effingham County at the 57th percentile among zone peers. Geologically, Effingham County is grouped into EPA Region 5 alongside 523 other counties that share its rock and soil setting.

Why the zone isn't the answer by itself

Call it a middle case: above the 1.3 pCi/L most US homes average, below the 4 pCi/L line EPA uses to recommend mitigation — that's Effingham County's Zone 2 prediction. Nothing about a Zone 2 label lowers the case for testing in Effingham County — EPA recommends it in every zone, moderate included.

If Effingham County tests above the action level

Nothing about Effingham County's EPA zone changes the mitigation number: $800–$2,500 nationally (around $1,200 typical), set by the house's foundation rather than the county it sits in — and only relevant once a test actually clears 4 pCi/L.

Find Illinois's state radon program

Effingham County's test kit answers today; a Airthings radon monitor keeps answering for Effingham County over time. Affiliate link, RadonZoneCheck earns a commission there, at no extra cost to you. RADONZONE-10OFF at checkout knocks 10% off.

More on how this number was built

The methodology guide shows exactly which EPA and Census sources feed Effingham County's numbers. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.