Is Buchanan County, MO a radon risk area?

EPA places Buchanan County in Zone 1 - Highest Potential — a predicted county-wide average indoor radon level above 4 pCi/L, based on the geology, soil and aerial radioactivity data behind EPA's national map. Rank it against the rest of the country and Buchanan County lands in the 93rd percentile for radon potential.

How Buchanan County compares

About 83,574 people live in Buchanan County, Missouri, spread over 408.249 square miles. Population density there runs about 205 people per square mile. Rank 221 by population within its EPA zone puts Buchanan County at the 79th percentile among zone peers. EPA's geology-based Region 7 groups Buchanan County with 411 other counties nationally sharing its underlying rock and soil profile.

Why the zone isn't the answer by itself

Buchanan County carries a Zone 1 label because its predicted average clears 4 pCi/L outright — three-plus times the 0.4 pCi/L typical outdoors and above the 1.3 pCi/L most homes see. EPA's guidance doesn't change because of a Zone 1 label: test the house. What changes is the reason to not put it off in Buchanan County specifically.

If Buchanan County tests above the action level

Nothing about Buchanan County's EPA zone changes the mitigation number: $800–$2,500 nationally (around $1,200 typical), set by the house's foundation rather than the county it sits in — and only relevant once a test actually clears 4 pCi/L.

Find Missouri's state radon program

Buchanan County's test kit answers today; a Airthings radon monitor keeps answering for Buchanan County over time. Affiliate link, RadonZoneCheck earns a commission there, at no extra cost to you. RADONZONE-10OFF at checkout knocks 10% off.

More on how this number was built

Buchanan 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.