Otero County, CO: EPA's radon zone, explained

EPA places Otero 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. Nationally that's the 81st percentile for radon potential — Otero County outranks 81% of every county EPA has rated.

Otero County by the numbers

Otero County, Colorado is home to about 17,991 people across 1,261.946 square miles. Population density there runs about 14 people per square mile. By population, Otero County is the 601st largest of every county sharing its EPA zone — the 44th percentile by population within that zone. EPA's geology-based Region 8 groups Otero County with 290 other counties nationally sharing its underlying rock and soil profile.

Zone vs. an actual test

Where the national indoor average runs about 1.3 pCi/L, Otero County's Zone 1 rating puts its predicted county average above EPA's 4 pCi/L action level itself. 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 Otero County specifically.

If Otero County tests above the action level

For a Otero 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 Colorado's state radon program

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

Where Otero County's figures come from

Otero County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.