What radon zone is Washington County, Oregon?

Washington County is EPA Radon Zone 2, which means the EPA predicts a predicted average indoor screening level between 2 and 4 pCi/L for the county. The EPA recommends that every home be tested here. Roughly one in three Zone 2 homes still reads at or above the 4 pCi/L action level.

Does a Zone 2 classification mean my home is safe?

No. The EPA zone is a county-level planning estimate, not a measurement of any individual house. Radon varies dramatically from house to house on the same street. The only way to know your home's level is to test it.

Washington County, Oregon radon zone: EPA Zone 2

What Zone 2 means in Washington County

The EPA recommends that every home be tested here. Roughly one in three Zone 2 homes still reads at or above the 4 pCi/L action level.

The EPA's Map of Radon Zones (EPA-402-R-93-071) sorts all 3,143 US counties into three tiers by predicted indoor screening level. Washington County sits in Zone 2. The classification is a planning assumption for builders, inspectors and buyers, and it is the figure a home inspector or realtor will cite for this county.

How Washington County compares inside Oregon

Of the 36 counties in Oregon on the EPA map, 0 are Zone 1, 21 are Zone 2 and 15 are Zone 3. Washington County is one of the 21 Oregon counties classified Zone 2.

Why your own home still needs a test

Radon comes out of the soil and enters through the foundation, so two houses on the same street can read very differently depending on foundation cracks, soil contact and how the house is ventilated. A Zone 2 classification tells you the county's planning assumption, not your reading. A short-term test kit costs about $15 to $30 and settles it. Many state radon programs also offer free or low-cost kits.

ZIP codes in Washington County

97003, 97005, 97006, 97007, 97008, 97062, 97075, 97076, 97077, 97078, 97079, 97106, 97109, 97113, 97116, 97117, 97119, 97123, 97124, 97125, 97129, 97133, 97140, 97144, 97223, 97224, 97225, 97229, 97281, 97291, 97298

Get the full dossier for your ZIP

The $9 Washington County radon report gives you the county's EPA zone, the expected indoor average, your home's estimated likelihood of testing above the 4 pCi/L action level adjusted for basement and home type, the mitigation cost band, and the EPA lifetime-risk figures, on one printable page you can hand to a buyer's inspector.

Check my radon zone · $9

Source

Zone classification: US EPA Map of Radon Zones, county table (EPA-402-R-93-071 / EPA 402/A-16/001). Population: US Census Bureau county population estimates, 2024 vintage. This page reports the EPA's own classification for Washington County exactly as published. We do not interpolate or adjust it.

Washington County, Oregon is in EPA Radon Zone 2