State Overview

Radon Levels in Alabama: County-by-County Guide.

The short version: radon in Alabama has been measured in every one of the state's 67 counties. The Alabama Department of Public Health (ADPH) names 15 of them as the state's highest-potential radon counties — and Jefferson and Shelby, the two counties that carry the Birmingham metro, are both on that list. Here is what the measured data actually says, county by county.

15counties

ADPH highest-potential list

13Zone 1

EPA highest-potential zone counties

4.0pCi/L

EPA action level

ADPH Statement

What the State Actually Says

The Alabama Department of Public Health puts it plainly: homes with high radon have been found in every state, including Alabama, and radon levels (measured in pCi/L — picocuries per liter, just a unit for how much radon is in the air) can vary greatly from home to home — even next-door houses can read very differently. ADPH's recommendation is that all Alabama homes be tested.

ADPH also names 15 counties as having the highest potential for elevated radon levels:

Calhoun
Clay
Cleburne
Colbert
Coosa
Franklin
Jackson
Jefferson
Lauderdale
Lawrence
Limestone
Madison
Morgan
Shelby
Talladega

Both Birmingham metro counties — Jefferson and Shelby— are on ADPH's 15-county highest-potential list.

Source: Alabama Department of Public Health, “Radon in Alabama,” page last updated February 4, 2026.

Birmingham Metro

Birmingham Metro: Jefferson, Shelby, St. Clair

CDC Environmental Public Health Tracking Network data covering 2008 to 2017 is the most defensible measured dataset available at the county level. Here is what it shows for the three counties that carry the Birmingham metro.

10.7%

Jefferson County tests at or above 4.0 pCi/L (n ~630)

11.3%

Shelby County tests at or above 4.0 pCi/L (n ~283)

14.0%

St. Clair County tests at or above 4.0 pCi/L (n ~70)

Roughly 1 in 9 reported tests in Jefferson and Shelby, and 1 in 7 in St. Clair, came back at or above the EPA action level of 4.0 pCi/L. Jefferson's highest individual reading in the dataset was 24.6 pCi/L; Shelby's was 14.6 pCi/L; St. Clair's was 12.1 pCi/L. Averages are lower than those headline numbers — Jefferson and Shelby both average 1.9 pCi/L, St. Clair averages 2.1 — but the point of a radon test is to identify the individual homes that come back high, not to reassure a whole county.

Note the EPA zone designation for all three counties is Zone 2, not Zone 1. ADPH separately names Jefferson and Shelby among Alabama's 15 highest-potential radon counties — that state-level designation and the EPA's 1993 zone map are two different rating systems.

Measured Data

County-by-County Measured Radon (CDC 2008–2017)

The table below covers the Birmingham metro and priority north-Alabama counties. Averages are in pCi/L. The “% at or above 4.0” column is the share of reported tests that hit or exceeded the EPA action level. The test count (n) matters — a high percentage on a very small sample is not the same finding as a high percentage on hundreds of tests.

County	EPA Zone	ADPH high-potential	CDC avg	Median	% ≥ 4.0	Highest reading	# tests
Jefferson	Zone 2	YES	1.9	1.2	10.7%	24.6	~630
Shelby	Zone 2	YES	1.9	1.3	11.3%	14.6	~283
St. Clair	Zone 2	no	2.1	1.2	14.0%	12.1	~70
Blount	Zone 2	no	2.8	2.0	13.6%	28.3	~36
Walker	Zone 2	no	2.3	1.4	33.3%	5.5	~12
Tuscaloosa	Zone 2	no	2.4	1.4	8.5%	27.0	~51
Talladega	Zone 1	YES	2.5	1.6	18.5%	27.0	~98
Calhoun	Zone 1	YES	2.8	1.4	18.9%	26.0	~181
Madison	Zone 1	YES	4.0	1.9	25.2%	261.0	~2,959
Morgan	Zone 1	YES	2.9	1.4	14.6%	96.7	~344
Limestone	Zone 1	YES	2.3	1.3	10.1%	87.0	~501
Cullman	Zone 2	no	2.0	1.5	11.4%	9.1	~63

Sources: CDC Environmental Public Health Tracking Network (2008–2017), republished per county at radonverdict.com; EPA 1993 Map of Radon Zones; ADPH “Radon in Alabama.”

Two honest caveats worth noting. First, Walker County's 33.3% at or above 4.0 pCi/L is drawn from only about a dozen tests — too small a sample to headline as a countywide finding. Second, Madison County's highest recorded reading in the dataset is 261 pCi/L from nearly 3,000 tests — a single house, but a real one. That is what “radon levels vary greatly from home to home” looks like on paper.

North Alabama

The Real Hot Zone Is North of Us

Birmingham metro numbers are meaningful, but the state's highest measured radon sits in a band across northern Alabama. From the same CDC dataset:

Colbert County — 36.2% of tests at or above 4.0 pCi/L (578 tests). Average around 5.3 pCi/L.
Lauderdale County — 27.2% at or above 4.0 (1,151 tests). Average around 3.5 pCi/L.
Madison County — 25.2% at or above 4.0 (2,959 tests). Average 4.0 pCi/L, highest recorded reading 261 pCi/L.
Lawrence County — 16.2% at or above 4.0 (124 tests). Highest recorded reading 226 pCi/L.

These are the counties where the EPA's Zone 1 designation and ADPH's highest-potential list overlap with a big enough test count to trust the pattern. If you are north of the Tennessee River, you are living on top of the state's hottest measured radon.

EPA Zones

Alabama's EPA Radon Zones, at a Glance

The EPA's 1993 Map of Radon Zones assigns every US county a zone based on predicted average indoor screening levels. Alabama's 67 counties break down as:

Zone 1 — 13 counties; highest potential, predicted average indoor screening level above 4.0 pCi/L.
Zone 2 — 33 counties; moderate potential, predicted 2–4 pCi/L. Jefferson, Shelby, and St. Clair are all Zone 2.
Zone 3 — 21 counties; low potential, predicted below 2 pCi/L.

The zone map is a 1993 county-level screening prediction, not a measurement of your specific home. EPA and ADPH both stress that elevated radon has been found in every zone. For the full 67-county zone table plus ZIP-to-county lookup, see Alabama radon levels by ZIP code.

Geology

Why Alabama Has the Radon It Has

Radon potential tracks with what is under the ground. According to the Geological Survey of Alabama, the state's highest radon potential corresponds to areas underlain by specific limestone, shale (including coal-bearing units), and granitic rocks. Permeability — karst, faulting, excavation, construction disturbance — is what lets that soil gas move up into a house.

The Birmingham metro sits inside the Valley and Ridge province, ranked moderate-to-high in geologic radon potential. Radon here comes mainly from altered carbonaceous and granitic rocks, and the province's characteristic faulting creates conduits for soil gas to move upward. The Appalachian Plateau immediately northwest of us — the terrain under parts of Jefferson, Blount, and Walker counties — is ranked moderate, with sandstones and carbonaceous shales including coal.

GSA's radon-hazards page lists nine radon-potential factors: hillside and slope siting, thin soils over bedrock, fractured rock, and limestone caverns among them — all common features of Birmingham metro topography.

Sources: Geological Survey of Alabama radon hazards page; GSA 2025 presentation “Geology and Radon in Alabama” (Brian S. Cook, EPA Region 4 Radon Stakeholders Meeting).

Regulation

An Honest Note About Alabama's Rules

Alabama has no radon disclosure requirement for real estate transactions and no state licensing for radon testers or mitigators. In practical terms, that means a seller does not have to tell a buyer about a prior high radon test, and anyone in the state can put a device in a house and call themselves a radon tester without a state credential.

The credential to look for instead is NRPP (National Radon Proficiency Program) or AARST certification, either for testing or for mitigation. Because there is no state license backstop, the equipment used, the protocol followed, and whether the reading comes from an independent lab are what actually separate a reliable Alabama radon result from a guess.

Testing in Jefferson, Shelby, or St. Clair? Book a 48-hour test.

Call (205) 000-0000 Birmingham metro service area

FAQ

Frequently Asked Questions

Is radon a real problem in Alabama?

Yes. The Alabama Department of Public Health states that homes with high radon have been found in every state, including Alabama, and identifies 15 counties as having the highest potential for elevated radon: Calhoun, Clay, Cleburne, Colbert, Coosa, Franklin, Jackson, Jefferson, Lauderdale, Lawrence, Limestone, Madison, Morgan, Shelby and Talladega. Both Birmingham metro counties, Jefferson and Shelby, are on that list.

What EPA radon zone is Birmingham in?

Jefferson and Shelby counties are EPA Zone 2 on the 1993 Map of Radon Zones. ADPH separately names both counties among Alabama's 15 highest-potential radon counties. The EPA zone map is a county-level screening prediction from 1993; both EPA and ADPH stress that elevated radon has been found in every zone and every home should be tested.

How often do Alabama homes test above 4.0 pCi/L?

In CDC data covering 2008 to 2017, roughly 1 in 9 reported tests in Jefferson County and Shelby County came back at or above the 4.0 pCi/L EPA action level, and roughly 1 in 7 in St. Clair County. Statewide, several north-Alabama counties are much higher: Colbert 36.2%, Lauderdale 27.2%, Madison 25.2%.

Does Alabama require radon disclosure when selling a home?

No. Alabama has no radon disclosure requirement for real estate transactions and does not license radon professionals at the state level. The credential to look for is NRPP or AARST certification. Because there is no state license, the equipment and protocol used on a test are what actually separate a reliable result from a guess.

Where do I look up radon results for my specific ZIP code?

The Alabama Department of Public Health runs an official Radon Measurement Lookup that returns average homeowner test results by ZIP code. It is the authoritative ZIP-level source. For the full 67-county EPA zone table, see our Alabama radon levels by ZIP code page.