What EPA's radon map says about Vernon County

EPA places Vernon 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. That puts Vernon County in the 86th percentile nationally for radon potential — higher than 86% of the counties EPA has rated.

Vernon County by the numbers

About 31,351 people live in Vernon County, Wisconsin, spread over 791.563 square miles. That works out to roughly 40 people per square mile. Among counties sharing Vernon County's EPA zone, it outranks 57% of them by population. Geologically, Vernon County is grouped into EPA Region 5 alongside 523 other counties that share its rock and soil setting.

Zone vs. an actual test

Outdoor air nationally averages about 0.4 pCi/L, indoor air about 1.3 pCi/L — Vernon 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 Vernon County specifically.

Next steps for a home in Vernon County

Mitigation cost doesn't depend on Vernon 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 Wisconsin's state radon program

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

More on how this number was built

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