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Radon Levels in Limestone County, Alabama

EPA puts Limestone County in Zone 1, its highest radon zone, and most reported tests there come back low, though 10.1% of 674 (2008 to 2017, laboratory totals) reached 4 pCi/L. Homes with elevated levels occur in all three zones, so only a test measures yours.

Data checked By Radon411Methodology

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  • Share at 4+ pCi/L

    10.1%

    11.8 pts below AL

    Limestone
    10.1%
    Alabama
    21.9%

    674 tests, 2008 to 2017

  • Median result

    1.3pCi/L

    Below action level

    Limestone
    1.3 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    674

    5th of 27 by tests

    Limestone
    674
    Madison
    5,178

    Reported to CDC before any fix, 2008 to 2017

  • EPA radon zone

    Zone 1

    Highest potential

    1. Zone 1
    2. 2
    3. 3

    1 highest, 3 lowest

    EPA predicts over 4 pCi/L indoors

  • Rank in Alabama

    23 of 27

    Lowest quarter

    Limestone
    10.1%
    Colbert
    36.2%

    By share, of 27 with 30+ tests

Read a result for Limestone County

Starts at Limestone County's median, 1.3 pCi/L

1.3pCi/L

EPA’s own thresholds; the figures are the area’s, never this home’s.

EPA’s reading of 1.3 pCi/L

Below 2 pCi/L

  1. Under 20 to 1.9 pCi/L
  2. 2 to 4consider a fix
  3. 4 and aboveEPA says fix it

This result is below 2 pCi/L, the level at which EPA says a fix should be considered. Limestone County's median reported result, 2008 to 2017.

Interpret this reading

The data

Limestone County, At a glance

Limestone County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Limestone County in and predicts an average indoor of greater than 4 pCi/L (greater than 150 Bq/m³) across the county. That is one forecast for the whole county, not a reading of any address in it; homes above EPA's turn up in all three zones.

USGS geologic potential: High across 100% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Limestone County, 2008 to 2017, laboratory

Reported results by concentration band, Limestone County, 2008 to 2017, laboratory
Under 2 pCi/L: 66%2 to 4 pCi/L: 24%4 pCi/L and above: 10%

Of 674 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Limestone County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L44265.6%
2 to 4 pCi/L16424.3%
4 pCi/L and above6810.1%
What these figures count

These are the 674 tests reported to CDC for Limestone County over 2008 to 2017 (laboratory totals), many from homes being sold or already suspected of a problem: they describe the county's reported tests, not this house.

Measured: CDC tracking data. Figure above: 2008 to 2017, laboratory. Measured data period: 2005 to 2017 (every CDC figure on file).

How to read these figures

Limestone County, Compared

Limestone County radon figures, compared

Calculated by Radon411

Limestone County reports fewer high tests than Alabama overall. 10.1% of its 674 tests over the 2008 to 2017 laboratory totals were at or above 4 pCi/L. That is 11.8 points below the 21.9% pooled from 65 Alabama counties.

Ordered from highest share down, it comes 23rd of 27 Alabama counties with 30 or more tests for the same period. Nationally, every county with a figure for the same period pools to 35.7%; Limestone County sits 25.6 points below it.

Next door, the shares run from 14.6% in Morgan County to 40.7% in Giles County, TN. The reported tests do not follow EPA's Zone 1 label for Limestone County (predicted average above 4 pCi/L): 10.1% of them reached 4 pCi/L, fewer than that label suggests.

Half the tests came in under 1.3 pCi/L and half over it; the single highest reached 87.0 pCi/L. The rest split 65.6% under 2 pCi/L and 24.3% from 2 to 4 (Alabama: 54.3% and 23.8%).

CDC's ten-year totals for Limestone County went from 708 tests (2005 to 2014) to 674 (2008 to 2017), the share going from 12.1% to 10.1%.

Limestone County against Alabama, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Limestone County
Limestone County67410.1%1.3 pCi/LThis county
Alabama, pooled65 counties, pooled12,56921.9%Not pooled+11.8 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled+25.6 points
Colbert Countyhighest in the state87136.2%2.7 pCi/L+26.1 points
Baldwin Countylowest in the state310.0%1.0 pCi/L−10.1 points
Giles County, TNborders it14040.7%3.3 pCi/L+30.6 points
Lauderdale County, ALborders it1,88527.2%2.2 pCi/L+17.1 points
Madison County, ALborders it5,17825.2%1.9 pCi/L+15.1 points
Lincoln County, TNborders it14920.8%1.9 pCi/L+10.7 points
Lawrence County, ALborders it15416.2%1.7 pCi/L+6.1 points
Morgan County, ALborders it45314.6%1.4 pCi/L+4.5 points
Where Limestone County's reported results fell, 2008 to 2017, laboratory, beside Alabama and the United States
ResultLimestone County testsLimestone County shareAlabama shareU.S. shareAgainst Alabama
Under 2 pCi/L44265.6%54.3%39.6%+11.3 points
2 to 4 pCi/L16424.3%23.8%24.7%+0.5 points
4 pCi/L and above6810.1%21.9%35.7%−11.8 points
Limestone County ranked among the 27 Alabama counties with 30 or more tests, by share at or above 4 pCi/L, 2008 to 2017, laboratory
CountyRankTestsAt or above 4 pCi/LMedian
Blount County17 of 274413.6%2.0 pCi/L
DeKalb County18 of 276813.2%0.9 pCi/L
Lee County19 of 278112.3%1.3 pCi/L
Cullman County20 of 277911.4%1.5 pCi/L
Shelby County21 of 2737311.3%1.3 pCi/L
Jefferson County22 of 2791210.7%1.2 pCi/L
Limestone County23 of 2767410.1%1.3 pCi/L
Montgomery County24 of 271039.7%0.9 pCi/L
Tuscaloosa County25 of 27828.5%1.4 pCi/L
Mobile County26 of 27523.8%0.5 pCi/L
Baldwin County27 of 27310.0%1.0 pCi/L
Limestone County ten-year laboratory totals, against Alabama's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestAlabama, pooledChange from the row before
2008 to 201767410.1%1.3 pCi/L87.0 pCi/L21.9%−1.9 points
2007 to 201670612.0%1.4 pCi/L87.0 pCi/L22.0%+0.1 points
2006 to 201568811.9%1.4 pCi/L87.0 pCi/L22.0%−0.2 points
2005 to 201470812.1%1.4 pCi/L87.0 pCi/L22.4%First on file

Pooled shares: Radon411's sum of CDC's county counts for one period.

Limestone County, Geology

The ground under Limestone County

Predicted

USGS's geologic map puts all of Limestone County's mapped land in one class: high radon potential. The map puts 79.3% of Limestone County in the area it calls Interior Low Plateaus and 20.6% in Nashville Basin. USGS gives the first a radon index of 12 and the second 14, both in the high band (12 to 17).

USGS's geologic areas under Limestone County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Interior Low PlateausMississippian carbonate rocks and shales.High1279.3%
Nashville BasinMississippian Limestone.High1420.6%

Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.

Limestone County beside the ground around it

Limestone County has more high-potential ground than Alabama as a whole: 100% of its land against 14.3%. Of the 6 counties that border it, none has as large a share of high-potential ground; Madison County comes nearest at 100%.

Share of land by USGS radon potential: Limestone County, the 6 counties bordering it and Alabama
AreaEPA zoneLow potentialModerate potentialHigh potential
Limestone CountyZone 1NoneNone100%
Morgan CountyZone 1None23.5%76.5%
Madison CountyZone 1NoneNone100%
Giles County, TNZone 1None0.1%99.9%
Lawrence CountyZone 1None28.9%71.1%
Lauderdale CountyZone 112.2%None87.8%
Lincoln County, TNZone 1None29.8%70.2%
Alabama67 counties, pooled by land areaVaries35.2%50.4%14.3%

The map rates the ground, not the air in any home.

Local help

Limestone County, Local resources

Radon testing and mitigation in Limestone County

What Alabama's program says
Phone
(334) 290-6244

What it means

Limestone County, Questions

Questions about radon in Limestone County

Are radon levels high in Limestone County?

Over the 2008 to 2017 laboratory totals, 10.1% of the radon tests reported to CDC for Limestone County, Alabama were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.3 pCi/L. Of 27 Alabama counties with 30 or more tests for the same period, 22 reported a higher share; pooled, the state comes to 21.9%.

Which counties border Limestone County?

Limestone County borders 6 counties: Morgan County, AL, Madison County, AL, Giles County, TN, Lawrence County, AL, Lauderdale County, AL and Lincoln County, TN.

Products

Limestone County, Products

Testing a home in Limestone County

In Limestone County, 10.1% of 674 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 21.9% pooled across Alabama. In Zone 1 the year-round level in Limestone County is the one to know: a long-term test (more than 90 days) or a monitor, with a short-term kit for a first answer.

Test kits and monitors3

See every kit and monitor

Limestone County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Limestone County

Explore

Limestone County, Bordering counties

Counties bordering Limestone County

Calculated by Radon411

Limestone County, Cities and towns

Cities and towns in Limestone County

Limestone County is growing: the Census Bureau puts it at 122,928 residents on July 1, 2025, up 18.0% from 104,193 in 2020. That works out to 220 people per square mile of land. Huntsville, the largest place on its list (233,627 residents in all), extends beyond Limestone County, so no share of the total is worked out for it. Testing is reported here more often than across the state: CDC's 674 reported tests for 2008 to 2017 come to 5.5 for every 1,000 residents (2025 estimate), against 2.4 for Alabama.

From Huntsville to Mooresville, CDC publishes no figure by town: each reads Limestone County's.

The cities and towns in Limestone County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Huntsvilleextends beyond Limestone County233,627+8.0%Counted whole
Madisonextends beyond Limestone County67,968+18.8%Counted whole
Decaturextends beyond Limestone County58,056+1.6%Counted whole
Athens34,209+33.0%27.8%
Ardmore1,485+11.5%1.2%
Elkmont452+8.9%0.4%
Lester122+9.9%Under 0.1%
Mooresville48+9.1%Under 0.1%

8 incorporated places, as listed in the U.S. Census Bureau’s 2020 place reference files. Residents: U.S. Census Bureau population estimates for July 1, 2025 (Vintage 2025). A place that extends beyond Limestone County is counted whole, so it has no share.

Limestone County, Homes

Homes in Limestone County

Limestone County is a place of houses on their own lots: 79% of its 43,487 homes are detached single-family houses, against 69% across Alabama. Much of Limestone County is recent building: 45% of its homes have gone up since 2000 and the middle year built is 1996, against 1985 for Alabama. Owners live in 77% of the occupied homes (Alabama: 70%), so for most households a test and a fix are their own to order.

Homes in Limestone County, Alabama, 2019 to 2023
HomesLimestone CountyAlabama
Housing units43,4872,316,192
Detached houses79%69%
In buildings of 5 or more7%12%
Mobile homes10%13%
Built before 196010%16%
Built since 200045%27%
Middle year built19961985
Owner-occupied77%70%

Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.