What EPA's radon map says about Merced County

EPA places Merced County in Zone 3 - Low Potential — a predicted county-wide average indoor radon level below 2 pCi/L, based on the geology, soil and aerial radioactivity data behind EPA's national map. Rank it against the rest of the country and Merced County lands in the 30th percentile for radon potential.

How Merced County compares

About 296,774 people live in Merced County, California, spread over 1,938.02 square miles. Averaged across its land area, Merced County runs about 153 people per square mile. Among counties sharing Merced County's EPA zone, it outranks 92% of them by population. Merced County falls in EPA Radon Region 9, one of 95 counties nationally EPA assigns to that same geologic province.

Zone vs. an actual test

Merced County's predicted average sits below the national indoor average of about 1.3 pCi/L, well under EPA's 4 pCi/L action level. Don't read Zone 3 as a pass for Merced County — EPA's guidance to test every home makes no exception for counties predicted low.

Next steps for a home in Merced County

Mitigation cost doesn't depend on Merced 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

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

More on how this number was built

Every figure on this page traces to EPA's own Map of Radon Zones and Census data, documented in the methodology guide. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.