Alameda County, CA radon potential

Alameda 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 Alameda County lands in the 66th percentile for radon potential.

How Alameda County compares

Alameda County, California is home to about 1,649,060 people across 737.459 square miles. Averaged across its land area, Alameda County runs about 2,236 people per square mile. Within its own EPA zone, Alameda County is bigger by population than 99% of the counties that share it. Alameda 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

Call it a middle case: above the 1.3 pCi/L most US homes average, below the 4 pCi/L line EPA uses to recommend mitigation — that's Alameda County's Zone 2 prediction. Middle-of-the-pack doesn't mean risk-free for any one Alameda County address — a moderate county average still leaves individual homes to test either side of it.

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

Where Alameda County's figures come from

The methodology guide shows exactly which EPA and Census sources feed Alameda County's numbers. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.