Washington County, RI radon potential

EPA's own radon map rates Washington County zone 1 - highest potential, predicting a county-wide average indoor level above 4 pCi/L. That puts Washington County in the 95th percentile nationally for radon potential — higher than 95% of the counties EPA has rated.

Where Washington County sits nationally

Washington County, Rhode Island is home to about 130,333 people across 329.279 square miles. Population density there runs about 396 people per square mile. Within its own EPA zone, Washington County is bigger by population than 86% of the counties that share it. Washington County falls in EPA Radon Region 1, one of 59 counties nationally EPA assigns to that same geologic province.

Zone vs. an actual test

Fixing a home becomes an EPA recommendation past 4 pCi/L, and that is precisely the side of the line Washington County's Zone 1 prediction lands on, well above the roughly 1.3 pCi/L most US homes average. Being in Zone 1 raises the odds Washington County homes test above the action level, but it does not mean any specific house does — EPA recommends every home be tested, in every zone, because the only way to know is to test.

Next steps for a home in Washington County

A short-term test kit is the standard first step and typically costs far less than mitigation itself. If a test comes back at or above 4 pCi/L, a radon mitigation system for a typical home runs roughly $800–$2,500 (around $1,200 for a common single-family install), driven mainly by foundation type, not by county.

Find Rhode Island's state radon program

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

Where Washington 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.