Hardin County, IL radon potential

EPA places Hardin 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 35th percentile for radon potential — Hardin County outranks 35% of every county EPA has rated.

Where Hardin County sits nationally

Hardin County, Illinois is home to about 3,550 people across 177.39 square miles. That works out to roughly 20 people per square mile. Within its own EPA zone, Hardin County is bigger by population than 6% of the counties that share it. Hardin County falls in EPA Radon Region 5, one of 524 counties nationally EPA assigns to that same geologic province.

Zone vs. an actual test

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 Hardin County's Zone 2 prediction. Nothing about a Zone 2 label lowers the case for testing in Hardin County — EPA recommends it in every zone, moderate included.

If Hardin 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 Hardin County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Hardin 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 Hardin County's figures come from

Hardin County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. Whatever zone Hardin County carries, the zone explainer covers what it does and doesn't tell you about any one house.