What EPA's radon map says about Rio Blanco County
EPA places Rio Blanco 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. Rio Blanco County sits at the 72nd percentile nationally for radon potential — above 72 of every 100 rated counties.
Where Rio Blanco County sits nationally
About 6,607 people live in Rio Blanco County, Colorado, spread over 3,220.971 square miles. Averaged across its land area, Rio Blanco County runs about 2 people per square mile. Among counties sharing Rio Blanco County's EPA zone, it outranks 19% of them by population. EPA's geology-based Region 8 groups Rio Blanco County with 290 other counties nationally sharing its underlying rock and soil profile.
Zone vs. an actual test
Rio Blanco 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. A Zone 1 rating means testing is worth doing sooner rather than later, but it is still county-wide average, not a reading for any single house — some homes in Rio Blanco County will test well under the action level, and EPA's guidance is to test regardless of zone.
Next steps for a home in Rio Blanco County
Mitigation cost doesn't depend on Rio Blanco 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
Rio Blanco County's test kit answers today; a Airthings radon monitor keeps answering for Rio Blanco County over time. Affiliate link, RadonZoneCheck earns a commission there, at no extra cost to you. Code RADONZONE-10OFF takes 10% off at checkout.
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.