St. Louis County, MN Radon Zone Data

St. Louis County, MN: EPA's radon zone, explained

EPA places St. Louis 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. St. Louis County sits at the 62nd percentile nationally for radon potential — above 62 of every 100 rated counties.

Where St. Louis County sits nationally

St. Louis County, Minnesota is home to about 200,794 people across 6,248.121 square miles. Population density there runs about 32 people per square mile. By population, St. Louis County is the 121st largest of every county sharing its EPA zone — the 88th percentile by population within that zone. St. Louis County falls in EPA Radon Region 5, one of 524 counties nationally EPA assigns to that same geologic province.

What this actually means for a house in St. Louis County

Neither at the 4 pCi/L action level nor down at the roughly 1.3 pCi/L national indoor norm, St. Louis County's Zone 2 prediction lands in the gap between the two. St. Louis County's Zone 2 rating sits in the middle nationally; EPA's guidance is unchanged by that — test every home regardless of its zone.

If St. Louis County tests above the action level

For a St. Louis 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 Minnesota's state radon program

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

Where St. Louis 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.