What EPA's radon map says about San Miguel County

EPA places San Miguel 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. That puts San Miguel County in the 74th percentile nationally for radon potential — higher than 74% of the counties EPA has rated.

San Miguel County by the numbers

About 7,819 people live in San Miguel County, Colorado, spread over 1,286.725 square miles. That works out to roughly 6 people per square mile. Among counties sharing San Miguel County's EPA zone, it outranks 23% of them by population. Geologically, San Miguel County is grouped into EPA Region 8 alongside 290 other counties that share its rock and soil setting.

What this actually means for a house in San Miguel County

San Miguel County's predicted average sits above EPA's own action level of 4 pCi/L — the concentration at which EPA recommends fixing a home — versus a national average around 1.3 pCi/L indoors and 0.4 pCi/L outdoors. Being in Zone 1 raises the odds San Miguel County homes test above the action level, but it does not mean any specific house does — EPA recommends every home be tested, in every zone, because the only way to know is to test.

Testing and mitigation in San Miguel County

Mitigation cost doesn't depend on San Miguel County's zone — it depends on the house's foundation. A typical system runs $800–$2,500 (about $1,200 typical), and testing first is what tells you whether that's needed at all.

Find Colorado's state radon program

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

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.