Tuolumne County, CA radon potential

EPA's own radon map rates Tuolumne County zone 2 - moderate potential, predicting a county-wide average indoor level between 2 and 4 pCi/L. Nationally that's the 55th percentile for radon potential — Tuolumne County outranks 55% of every county EPA has rated.

Where Tuolumne County sits nationally

Tuolumne County, California is home to about 53,893 people across 2,220.912 square miles. Population density there runs about 24 people per square mile. Within its own EPA zone, Tuolumne County is bigger by population than 68% of the counties that share it. Geologically, Tuolumne County is grouped into EPA Region 9 alongside 94 other counties that share its rock and soil setting.

What this actually means for a house in Tuolumne County

Tuolumne County's predicted average falls between EPA's 4 pCi/L action level and the national indoor average of about 1.3 pCi/L (outdoor air runs roughly 0.4 pCi/L). Tuolumne County's Zone 2 rating sits in the middle nationally; EPA's guidance is unchanged by that — test every home regardless of its zone.

Next steps for a home in Tuolumne County

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

Where Tuolumne County's figures come from

The methodology guide shows exactly which EPA and Census sources feed Tuolumne County's numbers. Whatever zone Tuolumne County carries, the zone explainer covers what it does and doesn't tell you about any one house.