Is Jefferson County, TN a radon risk area?

EPA's own radon map rates Jefferson County zone 1 - highest potential, predicting a county-wide average indoor level above 4 pCi/L. Rank it against the rest of the country and Jefferson County lands in the 91st percentile for radon potential.

Jefferson County by the numbers

About 59,217 people live in Jefferson County, Tennessee, spread over 275.155 square miles. Averaged across its land area, Jefferson County runs about 215 people per square mile. Rank 280 by population within its EPA zone puts Jefferson County at the 74th percentile among zone peers. Geologically, Jefferson County is grouped into EPA Region 4 alongside 735 other counties that share its rock and soil setting.

Why the zone isn't the answer by itself

Where the national indoor average runs about 1.3 pCi/L, Jefferson County's Zone 1 rating puts its predicted county average above EPA's 4 pCi/L action level itself. A Zone 1 rating means testing is worth doing sooner rather than later, but it is still county-wide average, not a reading for any single house — some homes in Jefferson County will test well under the action level, and EPA's guidance is to test regardless of zone.

Next steps for a home in Jefferson County

Nothing about Jefferson County's EPA zone changes the mitigation number: $800–$2,500 nationally (around $1,200 typical), set by the house's foundation rather than the county it sits in — and only relevant once a test actually clears 4 pCi/L.

Find Tennessee's state radon program

Jefferson County's test kit answers today; a Airthings radon monitor keeps answering for Jefferson County over time. Affiliate link, RadonZoneCheck earns a commission there, at no extra cost to you. Use code RADONZONE-10OFF at checkout for 10% off.

More on how this number was built

Every figure on this page traces to EPA's own Map of Radon Zones and Census data, documented in the methodology guide. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.