Is Rio Grande County, CO a radon risk area?

Rio Grande County is mapped as Zone 2 - Moderate Potential by EPA — meaning the county-wide average indoor level is predicted between 2 and 4 pCi/L. Nationally, Rio Grande County ranks higher in radon potential than 40% of rated counties (the 40th percentile).

How Rio Grande County compares

About 11,132 people live in Rio Grande County, Colorado, spread over 911.956 square miles. That works out to roughly 12 people per square mile. Rank 797 by population within its EPA zone puts Rio Grande County at the 23rd percentile among zone peers. Rio Grande County falls in EPA Radon Region 8, one of 291 counties nationally EPA assigns to that same geologic province.

Zone vs. an actual test

Neither at the 4 pCi/L action level nor down at the roughly 1.3 pCi/L national indoor norm, Rio Grande County's Zone 2 prediction lands in the gap between the two. Middle-of-the-pack doesn't mean risk-free for any one Rio Grande County address — a moderate county average still leaves individual homes to test either side of it.

Testing and mitigation in Rio Grande County

Nothing about Rio Grande 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 Colorado's state radon program

Rio Grande County's test kit answers today; a Airthings radon monitor keeps answering for Rio Grande County over time. Affiliate link, RadonZoneCheck earns a commission there, at no extra cost to you. Use code RADONZONE-10OFF at checkout for 10% off.

More on how this number was built

The methodology guide shows exactly which EPA and Census sources feed Rio Grande County's numbers. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.