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

EPA's own radon map rates Perry County zone 2 - moderate potential, predicting a county-wide average indoor level between 2 and 4 pCi/L. Nationally, Perry County ranks higher in radon potential than 46% of rated counties (the 46th percentile).

How Perry County compares

Perry County, Illinois is home to about 20,272 people across 441.928 square miles. Averaged across its land area, Perry County runs about 46 people per square mile. By population, Perry County is the 622nd largest of every county sharing its EPA zone — the 40th percentile by population within that zone. Perry County falls in EPA Radon Region 5, one of 524 counties nationally EPA assigns to that same geologic province.

What this actually means for a house in Perry County

Perry County's Zone 2 prediction clears the 1.3 pCi/L national indoor average without reaching EPA's own 4 pCi/L point for recommending a fix. Perry County's Zone 2 rating sits in the middle nationally; EPA's guidance is unchanged by that — test every home regardless of its zone.

If Perry County tests above the action level

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

Perry 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.