Is Knox County, MO a radon risk area?

EPA places Knox 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. Knox County sits at the 35th percentile nationally for radon potential — above 35 of every 100 rated counties.

How Knox County compares

About 3,740 people live in Knox County, Missouri, spread over 504.01 square miles. Population density there runs about 7 people per square mile. Rank 970 by population within its EPA zone puts Knox County at the 6th percentile among zone peers. Geologically, Knox County is grouped into EPA Region 7 alongside 411 other counties that share its rock and soil setting.

What this actually means for a house in Knox County

EPA's Zone 2 rating for Knox County sits below its own 4 pCi/L action level but above the national indoor average of about 1.3 pCi/L. Middle-of-the-pack doesn't mean risk-free for any one Knox County address — a moderate county average still leaves individual homes to test either side of it.

Testing and mitigation in Knox County

Nothing about Knox 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

Knox County's test kit answers today; a Airthings radon monitor keeps answering for Knox 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

The methodology guide shows exactly which EPA and Census sources feed Knox County's numbers. Whatever zone Knox County carries, the zone explainer covers what it does and doesn't tell you about any one house.