Tennessee Radon Authority
Updated October 17, 2026

Obion County radon · Union City, South Fulton & Troy

Obion County radon. Low-potential zone, no construction mandate.

Obion County is mapped as EPA Zone 3 and the state dashboard shows a 1.6 pCi/L average. But no reviewed jurisdiction requires radon-resistant construction, and no nationally certified tester is based in the county.

Research checked October 16, 2026Two live dashboard reads
Editorial cutaway illustration of radon moving through soil and foundation openings beneath a rural West Tennessee brick home
County zones describe broad potential. A test is the only way to know the radon level in one home.

Radon in Obion County, Tennessee: quick answers

EPA zone: Zone 3Region: West TennesseeState test data: State test figures confirmed on repeat checks

Is radon a problem in Obion County, Tennessee?

It can be. Obion County is in EPA Zone 3, the lowest predicted radon-potential category (below 2 pCi/L on average). Homes with high radon are still found in Zone 3, and the Tennessee Radon Program has found homes needing action in every Tennessee county, so test to know your home's level.

Do new homes in Obion County, TN have to be built radon-resistant?

No. Unincorporated Obion County and Troy are listed as opted out, and Union City and South Fulton adopted the 2018 code without the radon appendix. Local code details

How do I test my home for radon in Obion 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 Obion 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 Obion County from nearby cities. How to choose a radon professional

01 / QUICK READ

Low predicted potential. Almost no built-in safeguard.

Radon-resistant new construction is required nowhere in Obion County.

Unincorporated Obion County and Troy are listed as opted out of state residential enforcement. Union City and South Fulton enforce the 2018 IRC but do not adopt Appendix F, the radon appendix. [1] [2] [3] [4]

Bottom line
Do not use Zone 3 or a new-home label as a substitute for testing.
Zone 3EPA lower-potential designation: predicted county average below 2 pCi/L. [5]
1.6pCi/L dashboard average, confirmed twice with Obion’s own tooltip label. [6]
0NRPP- or NRSB-listed measurement professionals based in Obion County. [7] [8]
47 miDistance from Union City to the nearest visible NRPP listing, in Kevil, Kentucky. [7]
02 / RISK & DATA

The county average is below 2. The sample size is unknown.

EPA’s zone map predicts broad potential. Tennessee’s 2022–2023 dashboard is a limited testing snapshot, not a property-level answer.

EPA radon potential
Zone 3

Predicted average indoor screening level below 2 pCi/L. The designation does not establish that any individual home is safe. [5]

COUNTY LABEL VERIFIED TWICE

Tennessee Radon Testing dashboard

1.6Average · pCi/L
BlankMedian field
BlankMaximum field

On two separate loads, the tooltip’s own accessibility label confirmed “County: Obion” and showed the same average. Median and maximum did not display, so they are not published. The test count is also unavailable. [6]

The lower charts are health-region totals—not Obion County counts.

The pre- and post-mitigation charts remained region aggregates during the county checks. Dyer and Lake showed “No Events,” underscoring how thin the visible local dataset is. No regional bar or percentage is presented here as an Obion County statistic.

03 / BUILDING CODES

Four jurisdictions, the same radon result.

None of the reviewed pathways makes an IRC radon appendix mandatory.

LISTED OPT OUT

Unincorporated Obion County

The freshest public jurisdiction source found lists Obion County as OPT OUT. The State Fire Marshal therefore does not enforce the 2018 IRC in unincorporated areas, and no county residential code was found. [4]

Practical result: no residential code inspection and no radon requirement. Opt-out status must be renewed after elections, so confirm it before a project.
2018 IRC · APPENDIX F NOT STATED

Union City

The city’s Building Codes page confirms the 2018 IRC for residential work and 2021 ICC editions for other structures. It states no IRC appendix adoption, so Appendix F is not mandatory. [1]

The current adopting ordinance number and effective date were not published online.
2018 IRC · NO APPENDICES LISTED

South Fulton

Municipal Code §12-501 adopts the 2018 IRC through Ordinance #2016-06 (November 2016). The adoption line lists no appendices, and the local modifications address sprinklers and energy testing—not radon. [2]

Result: radon-resistant construction is optional inside South Fulton.
LISTED OPT OUT · VERIFY CURRENT STATUS

Troy

The state jurisdiction table lists Troy as OPT OUT. The town’s official site shows no codes department or published code adoption. No evidence of a local residential code was found. [3] [4]

Likely result: no residential code enforcement. Confirm the current election-cycle opt-out status before relying on it.
No Obion-specific radon rule was found.

No local mandate surfaced for public buildings, schools or real-estate transactions. Tennessee law encourages school indoor-air evaluation and says it may include radon testing; it does not require it. [9]

How do I find a certified radon professional in Obion 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.

Search NRPPSearch NRSB

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.

04 / HOMEBUYERS

Put radon inside the inspection contingency.

Tennessee requires no radon test as a condition of sale. State disclosure instructions advise buyers to include radon among appropriate inspection contingencies. [10]

New does not automatically mean radon-ready.

No reviewed Obion County jurisdiction requires the IRC radon appendix. A new home in Union City or South Fulton may have no passive radon features, while a rural new home may receive no residential code inspection at all.

Ask the builder what was installed and request plans or photos of any passive system. Then test the completed home. The dashboard’s 1.6 average and Zone 3 label cannot answer for one property.

Transaction plan

  1. Write radon testing into the inspection or due-diligence window.
  2. Use an independent, nationally certified measurement professional where available.
  3. For a new build, ask for passive-system plans and installation photos.
  4. If mitigation is installed, retest to verify performance.
05 / TESTING RESOURCES

Start with Tennessee’s free test kit.

A do-it-yourself kit can screen a home. For a purchase or sale, use independent certified testing that fits the transaction timeline.

Search NRPPUse ZIP 38261 and confirm measurement credentialsSearch NRSBFilter for Radon Measurement SpecialistView Tennessee’s dashboardUse county-labeled tooltips; lower charts are regionalRead Tennessee disclosure guidanceRadon belongs in the buyer’s inspection contingency
06 / FAQ

Questions Obion County homeowners ask

Is Obion County in a high-radon zone?

No. Obion County is mapped as EPA Zone 3, the lower-potential category with a predicted average below 2 pCi/L. That broad label cannot predict one home, so testing is still the property-level answer.

What does the Tennessee dashboard show for Obion County?

Two county-labeled checks showed an average of 1.6 pCi/L. Median and maximum fields were blank, and the dashboard does not publish a county test count.

Does Obion County require radon-resistant new construction?

No reviewed jurisdiction requires it. Unincorporated Obion County is listed as opted out of state residential enforcement, while Union City and South Fulton use the 2018 IRC without adopting Appendix F.

Are certified radon testers based in Obion County?

The October 2026 directory checks found no NRPP- or NRSB-listed measurement professional based in the county. The nearest visible NRPP listing was about 47 miles away in Kevil, Kentucky.

Where can I get a radon test kit?

TDEC offers a free radon test kit to Tennessee homeowners. For a real-estate transaction, use an independent nationally certified professional where available and fit the test inside the due-diligence period.

07 / SOURCES

Primary documents, public data & directories

  1. Union City Building Codes — 2018 IRC residential and 2021 ICC editions for other structures.
  2. South Fulton Municipal Code, Title 12 — 2018 IRC adoption and local modifications.
  3. Town of Troy — published departments; no codes department shown.
  4. Tennessee residential jurisdiction summary — cites the State Fire Marshal’s August 21, 2026 table; corroborated by the MTAS jurisdiction table.
  5. EPA Map of Radon Zones: Tennessee; corroborated by the EPA Map of Radon Zones: Tennessee.
  6. Tennessee Radon Testing dashboard — two live Obion County tooltip checks, October 16, 2026.
  7. NRPP Find a Pro — Union City ZIP 38261 search, October 16, 2026.
  8. NRSB Find a Professional — 50- and 100-mile Radon Measurement Specialist searches.
  9. Tennessee Code §49-2-121 — voluntary school indoor-air evaluation and radon-testing language.
  10. Tennessee property-disclosure instructions — radon inspection-contingency guidance.
  11. State Fire Marshal residential permits — state 2018 IRC baseline.
  12. Obion County Private Act of 1976, Chapter 249 — assessor permit requirement.
  13. 2018 IRC Appendix F — Radon Control Methods.
  14. TDEC free radon test-kit request — statewide homeowner program.

Method note. This page separates verified local findings from inference and open questions. The 1.6 pCi/L average was published only after two matching county-labeled reads; blank fields remain blank. Health-region bars are not presented as county statistics. Directory results are dated snapshots, not a census.