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

EPA's own radon map rates Humphreys County zone 3 - low potential, predicting a county-wide average indoor level below 2 pCi/L. Rank it against the rest of the country and Humphreys County lands in the 4th percentile for radon potential.

Where Humphreys County sits nationally

Humphreys County, Mississippi is home to about 7,121 people across 418.635 square miles. Population density there runs about 17 people per square mile. By population, Humphreys County is the 900th largest of every county sharing its EPA zone — the 13th percentile by population within that zone. Geologically, Humphreys County is grouped into EPA Region 4 alongside 735 other counties that share its rock and soil setting.

Zone vs. an actual test

A Zone 3 county like Humphreys County is predicted closer to the 0.4 pCi/L typical outdoors than to EPA's 4 pCi/L action level. A Zone 3 label describes Humphreys County's average, not any one basement or slab in it — testing is still the only way an individual homeowner actually finds out.

If Humphreys County tests above the action level

For a Humphreys 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 Humphreys County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Humphreys 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 Humphreys 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. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.