What EPA's radon map says about Windham County

EPA places Windham County in Zone 2 - Moderate Potential — a predicted county-wide average indoor radon level between 2 and 4 pCi/L, based on the geology, soil and aerial radioactivity data behind EPA's national map. Nationally that's the 54th percentile for radon potential — Windham County outranks 54% of every county EPA has rated.

Windham County by the numbers

About 45,627 people live in Windham County, Vermont, spread over 785.959 square miles. That works out to roughly 58 people per square mile. Among counties sharing Windham County's EPA zone, it outranks 65% of them by population. EPA's geology-based Region 1 groups Windham County with 58 other counties nationally sharing its underlying rock and soil profile.

Why the zone isn't the answer by itself

EPA's Zone 2 rating for Windham County sits below its own 4 pCi/L action level but above the national indoor average of about 1.3 pCi/L. Windham County's Zone 2 rating sits in the middle nationally; EPA's guidance is unchanged by that — test every home regardless of its zone.

If Windham County tests above the action level

Mitigation cost doesn't depend on Windham 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 Vermont's state radon program

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

More on how this number was built

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.