EPA Zone
2
Moderate potential: predicted average indoor screening levels of 2–4 pCi/L.
01 / RISK SIGNAL
The map classification and the measured data point in different directions.
EPA Zone 2 predicts a broad 2–4 pCi/L indoor screening range. Tennessee’s 2022–2023 testing dashboard returns a radically higher DeKalb tooltip. Those are different kinds of evidence; neither replaces a test in a specific house.
Sources: EPA zone map · Tennessee Radon Testing dashboard59.7
pCi/L · DASHBOARD AVERAGE
14.9×EPA’s 4.0 pCi/L action level
59.2pCi/L · median
62.3pCi/L · maximum
Critical caveat: all three values were confirmed on three reads with “County: DeKalb” visible, but the dashboard shows no county test count. The median sitting close to the maximum is consistent with a very small sample; it is not proof of countywide exposure. The pre/post charts are health-region aggregates, not DeKalb counts.
Open the Tennessee dashboard · Year filter “(All)” = 2022–2023 tests02 / CODE SPLIT
Local enforcement is new. Radon requirements are not.
Select a jurisdiction to see the strongest published record. “Open” means the available record is dated or incomplete—not that a radon appendix is definitely absent.
Unincorporated DeKalb County
County-run inspections began in 2025.
Residential code2018 IRC
AuthorityResolution 2025-02-125
AdoptedMarch 31, 2025
The published policy summary lists no IRC appendices, so Appendix F—the 2018 radon appendix—is not shown as adopted. Davey Horton became the county’s first building inspector in 2025. The full resolution and final consolidated policy remain unavailable online.
Smithville
Local enforcement is current; the online ordinance is not.
Last verified edition2000 IRC
Last verified lawOrdinance #335
DatedFebruary 2003
The dated code copy adopts Appendices A, B, C, D, E, F, G, H, J and K; Appendix F was Radon Control Methods. A 2025 record confirms Smithville still has a building inspector, but no current edition or appendix list was found. Do not treat the 2003 appendix as confirmed current law.
Alexandria
The town reversed its earlier opt-out.
2012 statusOpted out
Later actionOpted into state program
Current appendixNot verified
A WJLE archive reports a roughly 2016 vote to enter the State Residential Building Program. If unchanged, the state’s 2018 IRC plus Appendix Q applies and the radon appendix does not. Current post-election status needs state confirmation.
Liberty
Last published as state-enforced.
Last verified statusState program
Published recordAbout 2012
If unchanged2018 IRC + Appendix Q
The last-known state standard omits Appendix F, making radon-resistant new construction optional. No current jurisdiction-status update was found.
Dowelltown
Last published as opted out.
Last verified statusNo residential code
Published recordAbout 2012
Current statusNot verified
The MTAS jurisdiction table lists Dowelltown as opted out, with no residential inspection program. No later online update was found.
What can be said countywide
No current, enforceable radon-resistant construction mandate was confirmed anywhere in DeKalb County. That is certain for unincorporated areas under the published 2025 summary; it remains an open verification question for Smithville and the smaller towns because their online records are dated.
How do I find a certified radon professional in DeKalb 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 / HOMEBUYERS
A disclosure form covers known radon. It still does not create a test.
When Tennessee’s property-condition disclosure form is used, known environmental hazards include radon. State law also permits a disclaimer in qualifying sales and provides exemptions; it does not require a seller to test. The Tennessee REALTORS® form advises buyers to use a radon inspection contingency.
Put radon in the inspection contingency.
A disclosure can only reveal what a seller knows. Testing creates new information before the transaction becomes final.
Test new construction, too.
The county’s published 2025 code summary does not adopt the radon appendix, and new construction with a written warranty can be exempt from the state disclosure form.
Treat crawlspaces as a design detail, not a pass.
Crawlspace foundations appear frequently in lake-area listings. Foundation type changes test placement and mitigation design; it does not replace measurement.
Use a certified provider—or start with TDEC’s kit.
Tennessee does not license radon professionals. NRPP and NRSB are the national credentials; TDEC offers free test kits to homeowners.
04 / TESTING RESOURCES
Radon testing resources
Start with a test, know who to call, and act on the number—not the county’s zone label.
Test your home
- Free test kit from TDEC
Tennessee’s radon program offers kits to homeowners. - Buy a kit by phone: 1-800-SOS-RADON (1-800-767-7236)
- Live help with your questions: 1-800-55RADON (1-800-557-2366)
- Find a certified pro: NRPP 800-269-4174 · NRSB 866-329-3474
If your result comes back high
- 1-800-644-6999 — the Fix-It Hotline, for general guidance on lowering radon in your home.
Learn more
Why it matters
- Radon causes about 21,000 U.S. lung cancer deaths a year—the second-leading cause overall and the number-one cause among people who never smoked.
- Smoking plus radon raises the risk roughly ~9×.
- About 1 in 15 homes has high radon.
- Test every 2 years, or every 2 years with a mitigation system. EPA recommends taking action at 4 pCi/L and considering it between 2 and 4.
Hotline information: U.S. Environmental Protection Agency and Centers for Disease Control and Prevention. Health statistics: EPA, Health Risk of Radon and American Lung Association.
05 / RULES AROUND THE TEST
State law mostly encourages or discloses. It does not compel a test here.
No DeKalb-specific radon rule for public buildings, schools or real-estate transactions was found online.
Testing is encouraged, not required.
TCA §49-2-121 says an LEA’s indoor-air program may include radon testing. It sets no radon testing mandate or retest interval.
Disclosure depends on the route used.
When the property-condition form is used, it covers known radon. A permitted disclaimer or exemption may apply instead, and no route creates a statewide test requirement.
No Tennessee radon license.
National NRPP or NRSB certification is the relevant credential. TDEC’s statewide program is voluntary.
06 / SOURCES & METHOD
Read the dashboard as a signal, not a census.
This snapshot separates live observations from indexed records. Local code claims are bounded by the ordinances and summaries available online; open items are not silently resolved.
The DeKalb tooltip values and NRPP directory results were checked live on October 15, 2026. Other material comes from the cited government, institutional and local-news records. Exact county test counts were unavailable, and the dashboard’s health-region bands were not treated as county data.
No county exposure rate, prevalence estimate or transaction volume is inferred from missing data.
- Tennessee Radon Testing dashboard
- EPA Map of Radon Zones — Tennessee
- Tennessee Rule 0780-02-23
- WJLE · county building-inspector policy
- WJLE · first county inspector
- MTAS jurisdiction-status table
- Smithville Title 12
- NRPP professional directory
- TCA §49-2-121
- 2025 Tennessee Radon Fact Sheet
- Tennessee REALTORS® RF201 form
- MTIDA 2025 community profile
- Center Hill Lake listings
- The U.C. Now · zoning study
- NRSB certification application
- TDEC Radon Program