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

EPA places Holt 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. Nationally, Holt County ranks higher in radon potential than 70% of rated counties (the 70th percentile).

How Holt County compares

Holt County, Missouri is home to about 4,241 people across 462.696 square miles. Population density there runs about 9 people per square mile. By population, Holt County is the 944th largest of every county sharing its EPA zone — the 11th percentile by population within that zone. Holt County falls in EPA Radon Region 7, one of 412 counties nationally EPA assigns to that same geologic province.

What this actually means for a house in Holt County

Outdoor air nationally averages about 0.4 pCi/L, indoor air about 1.3 pCi/L — Holt County's Zone 1 prediction clears both of those and EPA's fix-it threshold besides. That doesn't mean every Holt County house tests high — a zone is a county-wide prediction, never a single-home reading — but it's a reason to test sooner rather than let it wait.

Testing and mitigation in Holt County

For a Holt 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 Holt County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Holt 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 Holt 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. Whatever zone Holt County carries, the zone explainer covers what it does and doesn't tell you about any one house.