Is Plumas County, CA a radon risk area?

EPA places Plumas County in Zone 2 - Moderate Potential — a predicted county-wide average indoor radon level between 2 and 4 pCi/L, based on the geology, soil and aerial radioactivity data behind EPA's national map. That puts Plumas County in the 45th percentile nationally for radon potential — higher than 45% of the counties EPA has rated.

How Plumas County compares

About 18,834 people live in Plumas County, California, spread over 2,553.062 square miles. Averaged across its land area, Plumas County runs about 7 people per square mile. Rank 645 by population within its EPA zone puts Plumas County at the 38th percentile among zone peers. Plumas County falls in EPA Radon Region 9, one of 95 counties nationally EPA assigns to that same geologic province.

Why the zone isn't the answer by itself

EPA's Zone 2 rating for Plumas County sits below its own 4 pCi/L action level but above the national indoor average of about 1.3 pCi/L. Nothing about a Zone 2 label lowers the case for testing in Plumas County — EPA recommends it in every zone, moderate included.

Testing and mitigation in Plumas County

Nothing about Plumas County's EPA zone changes the mitigation number: $800–$2,500 nationally (around $1,200 typical), set by the house's foundation rather than the county it sits in — and only relevant once a test actually clears 4 pCi/L.

Find California's state radon program

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

More on how this number was built

Plumas County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.