Laramie County, WY: EPA's radon zone, explained

EPA places Laramie 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 94th percentile for radon potential — Laramie County outranks 94% of every county EPA has rated.

Where Laramie County sits nationally

Laramie County, Wyoming is home to about 101,783 people across 2,685.864 square miles. That works out to roughly 38 people per square mile. By population, Laramie County is the 191st largest of every county sharing its EPA zone — the 82nd percentile by population within that zone. Laramie County falls in EPA Radon Region 8, one of 291 counties nationally EPA assigns to that same geologic province.

Zone vs. an actual test

Laramie County carries a Zone 1 label because its predicted average clears 4 pCi/L outright — three-plus times the 0.4 pCi/L typical outdoors and above the 1.3 pCi/L most homes see. 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 Laramie County specifically.

If Laramie County tests above the action level

For a Laramie 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 Wyoming's state radon program

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

Where Laramie County's figures come from

Every figure on this page traces to EPA's own Map of Radon Zones and Census data, documented in the methodology guide. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.