The highest-potential category: predicted average indoor screening levels above 4 pCi/L.
Jefferson County radon · Tennessee
Jefferson County, TN radon Zone 1. Two cities built radon into the code.
Jefferson City and Dandridge adopted the IRC’s radon-control appendix. Outside them, the county’s appendix list remains unpublished—so buyers should verify the permit jurisdiction and test the finished home.
Douglas Lake image: Visit Jefferson County, Tennessee
Radon in Jefferson County, Tennessee: quick answers
EPA zone: Zone 1Region: East TennesseeState test data: State test figures couldn't be confirmed, so they aren't shown
Is radon a problem in Jefferson County, Tennessee?
Yes, it can be. Jefferson County is in EPA Zone 1, the highest radon-potential category, where the predicted average indoor screening level is above 4 pCi/L. Levels vary from house to house, so a test is the only way to know your home's level.
Do new homes in Jefferson County, TN have to be built radon-resistant?
In Jefferson City and Dandridge, yes: both specifically adopt the radon appendix (Appendix F). Unincorporated Jefferson County enforces the 2018 code, but its appendix list couldn't be confirmed. Local code details
How do I test my home for radon in Jefferson County?
Order a free short-term kit from the Tennessee Radon Program online or by calling 1-800-232-1139. Place it on the lowest lived-in floor, about 3 feet off the floor, for 3 to 5 days, then mail it back right away. How to test your home
What radon level means I should fix my home?
EPA recommends fixing your home if radon is 4 pCi/L or higher, and considering a fix between 2 and 4 pCi/L. Confirm a high short-term result with a second test first. What your result means
Who can test or fix radon in Jefferson County?
Tennessee doesn't license radon professionals, so look for NRPP or NRSB certification. Search both national directories by ZIP code; certified professionals often serve Jefferson County from nearby cities. How to choose a radon professional
Jefferson City and Dandridge both include the radon-control appendix in their residential codes.
Only one of the three nearby listings is measurement-only; NRSB showed none within 25 miles.
01 / Risk & evidence
High potential, no trustworthy county reading
EPA’s map places Jefferson County in Zone 1. Tennessee’s dashboard could not provide a reliably isolated Jefferson County tooltip after four attempts, so this guide publishes no county average, median or maximum.
The dashboard limit is the finding
Repeated hovers landed on Cocke, Greene and Sevier counties rather than Jefferson. Publishing one of those values as Jefferson County data would be a mislabel, not an estimate.
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County readings withheldAverage, median, maximum and county test count were not verified. The workbook offers no data export.
The pre- and post-mitigation bar charts are labeled by health region. Jefferson County is folded into the East Region group; those bars are not county totals. Open the Tennessee dashboard.
No map color can clear a house
Radon varies from building to building—even across the same street. Foundation type, construction details, soil pathways and pressure changes all matter. Test the address rather than borrowing a neighbor’s result or a countywide label.
02 / Building codes
The permit address changes the answer
Jefferson City and Dandridge expressly adopt Appendix F. Unincorporated Jefferson County confirms the 2018 IRC but has not published its adopting resolution or appendix list.
County enforcement
Unincorporated Jefferson County
Jefferson County Building Department
2018 IRC
Official county FAQ
Appendix F status, adopting resolution and effective date were not verified. A second FAQ on the same page still cites the 2012 IRC, so the record needs direct confirmation.
City enforcement
Jefferson City
City Building Department
2018 IRC
Ord. #2024-03 · May 2024
Appendix F is specifically included. In this Zone 1 county, its passive radon-control provisions are part of the enforceable residential code.
Town enforcement
Dandridge
Town Building / Codes Enforcement
2012 IRC
Ord. #13/14-12 · Dec. 2013
Appendix F is specifically included. No newer adoption was found; verify the codified text’s currency with the Town Recorder.
Jefferson City → Appendix F verifiedDandridge → Appendix F verified, currency caveatUnincorporated county → appendix status open
“Radon-ready” is not active mitigation
Appendix F provides passive construction measures such as a gas-permeable sub-slab layer, a soil-gas retarder and a capped vent rough-in for possible later activation. It does not mean an operating fan was installed or that the finished home tested below the EPA action level.
For unincorporated addresses, request the county’s adopting resolution and complete appendix list. The Building Department is listed at 865-397-0640. See the county department page.
How do I find a certified radon professional in Jefferson County?
Tennessee doesn't license radon testers or mitigators, so national certification is the best way to check qualifications. The Tennessee Radon Program points residents to two directories: search them by ZIP code and widen the radius if nothing is listed nearby.
We don't recommend or rank companies. Before you hire, check the certification number in the directory yourself and ask for a follow-up test after any system is installed. Questions to ask a radon professional.
03 / Homebuyer guide
Code helps. Testing decides.
Jefferson County’s growth, new construction and lake-area resale market make permit history worth checking. But neither a radon-ready detail nor a statewide disclosure answer replaces a measurement.
Identify the permit office
Confirm whether the address falls in Jefferson City, Dandridge or unincorporated Jefferson County before asking which IRC and appendices applied.
Ask for the radon details
For a new home, request plans and inspection records showing the sub-slab layer, soil-gas retarder, vent path and termination.
Test during due diligence
Tennessee’s seller disclosure form asks about radon gas, but “Unknown” is not a test result. Preserve enough inspection time for a valid measurement.
Retest after changes
Test after occupancy and after major HVAC, foundation or mitigation work. A passive system can be activated later if measurements warrant it.
04 / Quick answers
What the records establish
Clear answers where the documents are clear—and explicit limits where local records or dashboard data are missing.
Is Jefferson County a high-radon area?
Yes. EPA classifies Jefferson County as Zone 1, its highest-potential category, predicting average indoor screening levels above 4 pCi/L across the county. That designation cannot predict an individual home’s reading.
Does Jefferson City require radon-resistant new construction?
Yes. Jefferson City’s 2018 IRC adoption specifically includes Appendix F. In this Zone 1 county, the appendix’s passive radon-control provisions are part of the enforceable residential code.
What does Dandridge require?
Dandridge’s codified 2012 IRC adoption specifically includes Appendix F. The code text reflects Ordinance #13/14-12 from December 2013; because no newer adoption was found, verify its current status with the Town Recorder.
What about unincorporated Jefferson County?
The county’s official Building Department page says it adopted the 2018 IRC, but the adopting resolution, effective date and appendix list were not found online. Do not assume Appendix F applies until the county confirms it.
What county radon levels does Tennessee report?
This guide publishes none. Four attempts did not reliably isolate Jefferson County’s tooltip, and the workbook offers no export. The regional bars are East Region aggregates, not county totals.
How many certified testers are local?
Three NRPP-listed measurement professionals were based in or around Jefferson County: one measurement-only and two with both measurement and mitigation credentials. NRSB returned no professional within 25 miles of Jefferson City.