Is Delta County, CO a radon risk area?

Delta County is mapped as Zone 1 - Highest Potential by EPA — meaning the county-wide average indoor level is predicted above 4 pCi/L. Delta County sits at the 86th percentile nationally for radon potential — above 86 of every 100 rated counties.

How Delta County compares

About 32,215 people live in Delta County, Colorado, spread over 1,142.126 square miles. Population density there runs about 28 people per square mile. Rank 450 by population within its EPA zone puts Delta County at the 58th percentile among zone peers. Delta County falls in EPA Radon Region 8, one of 291 counties nationally EPA assigns to that same geologic province.

What this actually means for a house in Delta County

Outdoor air nationally averages about 0.4 pCi/L, indoor air about 1.3 pCi/L — Delta County's Zone 1 prediction clears both of those and EPA's fix-it threshold besides. EPA's guidance doesn't change because of a Zone 1 label: test the house. What changes is the reason to not put it off in Delta County specifically.

Next steps for a home in Delta County

Nothing about Delta 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

Delta County's test kit answers today; a Airthings radon monitor keeps answering for Delta 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 Delta County's numbers. Whatever zone Delta County carries, the zone explainer covers what it does and doesn't tell you about any one house.