San Luis Obispo County, CA radon potential

San Luis Obispo 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. Rank it against the rest of the country and San Luis Obispo County lands in the 63rd percentile for radon potential.

Where San Luis Obispo County sits nationally

San Luis Obispo County, California is home to about 281,843 people across 3,300.842 square miles. Population density there runs about 85 people per square mile. Within its own EPA zone, San Luis Obispo County is bigger by population than 92% of the counties that share it. Geologically, San Luis Obispo County is grouped into EPA Region 9 alongside 94 other counties that share its rock and soil setting.

Why the zone isn't the answer by itself

San Luis Obispo 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 county-wide moderate average, like San Luis Obispo County's, can still hide a specific house well above or below it — testing is what actually answers the question.

Next steps for a home in San Luis Obispo 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 California's state radon program

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

Where San Luis Obispo 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.