What EPA's radon map says about Kern County

Kern 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. That puts Kern County in the 65th percentile nationally for radon potential — higher than 65% of the counties EPA has rated.

Where Kern County sits nationally

About 922,529 people live in Kern County, California, spread over 8,134.673 square miles. Averaged across its land area, Kern County runs about 113 people per square mile. Among counties sharing Kern County's EPA zone, it outranks 98% of them by population. Geologically, Kern County is grouped into EPA Region 9 alongside 94 other counties that share its rock and soil setting.

What this actually means for a house in Kern County

Neither at the 4 pCi/L action level nor down at the roughly 1.3 pCi/L national indoor norm, Kern County's Zone 2 prediction lands in the gap between the two. Middle-of-the-pack doesn't mean risk-free for any one Kern County address — a moderate county average still leaves individual homes to test either side of it.

Next steps for a home in Kern County

Mitigation cost doesn't depend on Kern 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 California's state radon program

Kern County's test kit answers today; a Airthings radon monitor keeps answering for Kern County over time. Affiliate link, RadonZoneCheck earns a commission there, at no extra cost to you. Use code RADONZONE-10OFF at checkout for 10% off.

More on how this number was built

The methodology guide shows exactly which EPA and Census sources feed Kern County's numbers. Whatever zone Kern County carries, the zone explainer covers what it does and doesn't tell you about any one house.