Sacramento County, CA: EPA's radon zone, explained

EPA's own radon map rates Sacramento County zone 3 - low potential, predicting a county-wide average indoor level below 2 pCi/L. Nationally, Sacramento County ranks higher in radon potential than 33% of rated counties (the 33rd percentile).

How Sacramento County compares

Sacramento County, California is home to about 1,611,231 people across 965.38 square miles. That works out to roughly 1,669 people per square mile. By population, Sacramento County is the 14th largest of every county sharing its EPA zone — the 99th percentile by population within that zone. Geologically, Sacramento County is grouped into EPA Region 9 alongside 94 other counties that share its rock and soil setting.

Zone vs. an actual test

Sacramento 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. A Zone 3 label describes Sacramento County's average, not any one basement or slab in it — testing is still the only way an individual homeowner actually finds out.

Testing and mitigation in Sacramento County

For a Sacramento County homeowner, the order is simple: test first, since a kit costs a small fraction of what mitigation would. Only if the result clears 4 pCi/L does a system — typically $800–$2,500, about $1,200 for a common install — become worth pricing out.

Find California's state radon program

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

Where Sacramento County's figures come from

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