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

EPA's own radon map rates Simpson County zone 3 - low potential, predicting a county-wide average indoor level below 2 pCi/L. Nationally, Simpson County ranks higher in radon potential than 16% of rated counties (the 16th percentile).

How Simpson County compares

Simpson County, Mississippi is home to about 25,597 people across 589.165 square miles. Averaged across its land area, Simpson County runs about 43 people per square mile. By population, Simpson County is the 534th largest of every county sharing its EPA zone — the 48th 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.

Why the zone isn't the answer by itself

Simpson County's Zone 3 prediction undercuts the roughly 1.3 pCi/L most US homes average, nowhere near EPA's 4 pCi/L threshold for recommending mitigation. Don't read Zone 3 as a pass for Simpson County — EPA's guidance to test every home makes no exception for counties predicted low.

Testing and mitigation 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 Mississippi'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

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