Nevada County, CA radon potential
EPA places Nevada 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. Nationally that's the 60th percentile for radon potential — Nevada County outranks 60% of every county EPA has rated.
How Nevada County compares
Nevada County, California is home to about 102,195 people across 957.76 square miles. Averaged across its land area, Nevada County runs about 107 people per square mile. Within its own EPA zone, Nevada County is bigger by population than 81% of the counties that share it. EPA's geology-based Region 9 groups Nevada County with 94 other counties nationally sharing its underlying rock and soil profile.
Zone vs. an actual test
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 Nevada County's Zone 2 prediction. Nevada County's Zone 2 rating sits in the middle nationally; EPA's guidance is unchanged by that — test every home regardless of its zone.
If Nevada 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 Nevada County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Nevada County's levels over time. RadonZoneCheck earns a commission there, at no extra cost to you. Use code RADONZONE-10OFF at checkout for 10% off.
Where Nevada County's figures come from
Every figure on this page traces to EPA's own Map of Radon Zones and Census data, documented in the methodology guide. Whatever zone Nevada County carries, the zone explainer covers what it does and doesn't tell you about any one house.