Simpson County, KY: EPA's radon zone, explained

EPA places Simpson 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, Simpson County ranks higher in radon potential than 46% of rated counties (the 46th percentile).

Where Simpson County sits nationally

Simpson County, Kentucky is home to about 20,350 people across 234.185 square miles. Population density there runs about 87 people per square mile. By population, Simpson County is the 619th largest of every county sharing its EPA zone — the 40th percentile by population within that zone. EPA's geology-based Region 4 groups Simpson County with 735 other counties nationally sharing its underlying rock and soil profile.

Zone vs. an actual test

Simpson County's predicted average falls between EPA's 4 pCi/L action level and the national indoor average of about 1.3 pCi/L (outdoor air runs roughly 0.4 pCi/L). A county-wide moderate average, like Simpson County's, can still hide a specific house well above or below it — testing is what actually answers the question.

Next steps for a home in Simpson County

For a Simpson 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 Kentucky's state radon program

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

Simpson 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.