What EPA's radon map says about Robertson County

Robertson 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 Robertson County lands in the 58th percentile for radon potential.

Where Robertson County sits nationally

About 78,459 people live in Robertson County, Tennessee, spread over 476.336 square miles. Averaged across its land area, Robertson County runs about 165 people per square mile. Among counties sharing Robertson County's EPA zone, it outranks 77% of them by population. Robertson County falls in EPA Radon Region 4, one of 736 counties nationally EPA assigns to that same geologic province.

Zone vs. an actual test

Robertson 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). Nothing about a Zone 2 label lowers the case for testing in Robertson County — EPA recommends it in every zone, moderate included.

If Robertson County tests above the action level

Mitigation cost doesn't depend on Robertson County's zone — it depends on the house's foundation. A typical system runs $800–$2,500 (about $1,200 typical), and testing first is what tells you whether that's needed at all.

Find Tennessee's state radon program

Robertson County's test kit answers today; a Airthings radon monitor keeps answering for Robertson 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

Robertson County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. Whatever zone Robertson County carries, the zone explainer covers what it does and doesn't tell you about any one house.