What EPA's radon map says about Washington County

Washington County is mapped as Zone 2 - Moderate Potential by EPA — meaning the county-wide average indoor level is predicted between 2 and 4 pCi/L. Nationally, Washington County ranks higher in radon potential than 51% of rated counties (the 51st percentile).

How Washington County compares

About 31,383 people live in Washington County, Maine, spread over 2,562.726 square miles. Averaged across its land area, Washington County runs about 12 people per square mile. Among counties sharing Washington County's EPA zone, it outranks 54% of them by population. Geologically, Washington County is grouped into EPA Region 1 alongside 58 other counties that share its rock and soil setting.

What this actually means for a house in Washington County

Washington County's predicted average falls between EPA's 4 pCi/L action level and the national indoor average of about 1.3 pCi/L (outdoor air runs roughly 0.4 pCi/L). A Zone 2 rating is a moderate county-wide average, not a guarantee about any one house in Washington County — testing is the only way to know an individual home's actual level.

Next steps for a home in Washington County

Mitigation cost doesn't depend on Washington 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 Maine's state radon program

Washington County's test kit answers today; a Airthings radon monitor keeps answering for Washington 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

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.