Mississippi County, MO: EPA's radon zone, explained

Mississippi County is mapped as Zone 3 - Low Potential by EPA — meaning the county-wide average indoor level is predicted below 2 pCi/L. Mississippi County sits at the 8th percentile nationally for radon potential — above 8 of every 100 rated counties.

Mississippi County by the numbers

Mississippi County, Missouri is home to about 11,750 people across 411.596 square miles. That works out to roughly 29 people per square mile. By population, Mississippi County is the 777th largest of every county sharing its EPA zone — the 25th percentile by population within that zone. Geologically, Mississippi County is grouped into EPA Region 7 alongside 411 other counties that share its rock and soil setting.

Why the zone isn't the answer by itself

A Zone 3 county like Mississippi County is predicted closer to the 0.4 pCi/L typical outdoors than to EPA's 4 pCi/L action level. Don't read Zone 3 as a pass for Mississippi County — EPA's guidance to test every home makes no exception for counties predicted low.

Next steps for a home in Mississippi County

For a Mississippi 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 Missouri's state radon program

For Mississippi County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Mississippi County's levels over time. RadonZoneCheck earns a commission there, at no extra cost to you. RADONZONE-10OFF at checkout knocks 10% off.

Where Mississippi County's figures come from

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