Santa Barbara County, CA radon potential

EPA places Santa Barbara 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 Santa Barbara County in the 98th percentile nationally for radon potential — higher than 98% of the counties EPA has rated.

How Santa Barbara County compares

Santa Barbara County, California is home to about 444,500 people across 2,733.941 square miles. That works out to roughly 163 people per square mile. Within its own EPA zone, Santa Barbara County is bigger by population than 95% of the counties that share it. Santa Barbara County falls in EPA Radon Region 9, one of 95 counties nationally EPA assigns to that same geologic province.

Zone vs. an actual test

Where the national indoor average runs about 1.3 pCi/L, Santa Barbara County's Zone 1 rating puts its predicted county average above EPA's 4 pCi/L action level itself. Some Santa Barbara County homes will test comfortably under the action level despite the county's Zone 1 rating — the only way to know which kind of home you have is an actual test.

If Santa Barbara County tests above the action level

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 California's state radon program

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

Where Santa Barbara 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. Whatever zone Santa Barbara County carries, the zone explainer covers what it does and doesn't tell you about any one house.