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

EPA places Union 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. Union County sits at the 50th percentile nationally for radon potential — above 50 of every 100 rated counties.

How Union County compares

Union County, Mississippi is home to about 28,363 people across 415.607 square miles. That works out to roughly 68 people per square mile. By population, Union County is the 503rd largest of every county sharing its EPA zone — the 51st percentile by population within that zone. Geologically, Union County is grouped into EPA Region 4 alongside 735 other counties that share its rock and soil setting.

Why the zone isn't the answer by itself

Neither at the 4 pCi/L action level nor down at the roughly 1.3 pCi/L national indoor norm, Union County's Zone 2 prediction lands in the gap between the two. A Zone 2 rating is a moderate county-wide average, not a guarantee about any one house in Union County — testing is the only way to know an individual home's actual level.

If Union County tests above the action level

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

Where Union 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. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.