Adams County, IL Radon Zone Data

Adams County, IL radon potential

EPA's own radon map rates Adams County zone 1 - highest potential, predicting a county-wide average indoor level above 4 pCi/L. Nationally that's the 92nd percentile for radon potential — Adams County outranks 92% of every county EPA has rated.

Adams County by the numbers

Adams County, Illinois is home to about 64,109 people across 855.15 square miles. Population density there runs about 75 people per square mile. Within its own EPA zone, Adams County is bigger by population than 76% of the counties that share it. EPA's geology-based Region 5 groups Adams County with 523 other counties nationally sharing its underlying rock and soil profile.

What this actually means for a house in Adams County

Fixing a home becomes an EPA recommendation past 4 pCi/L, and that is precisely the side of the line Adams County's Zone 1 prediction lands on, well above the roughly 1.3 pCi/L most US homes average. Being in Zone 1 raises the odds Adams County homes test above the action level, but it does not mean any specific house does — EPA recommends every home be tested, in every zone, because the only way to know is to test.

Next steps for a home in Adams County

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 Adams County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Adams 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 Adams 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. Whatever zone Adams County carries, the zone explainer covers what it does and doesn't tell you about any one house.