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Radon Levels in Marshall County, Tennessee

EPA puts Marshall County in Zone 1, its highest radon zone, and only 1 radon test from it is on file with CDC (2023). 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

    18.1%

    15.2 pts below TN

    Marshall
    18.1%
    Tennessee
    33.3%

    138 tests, 2008 to 2017

  • Median result

    1.6pCi/L

    Below action level

    Marshall
    1.6 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    138

    37th of 80 by tests

    Marshall
    138
    Davidson
    5,592

    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 Tennessee

    61 of 80

    Lowest quarter

    Marshall
    18.1%
    Jefferson
    56.8%

    By share, of 80 with 30+ tests

Read a result for Marshall County

Starts at Marshall County's median, 1.6 pCi/L

1.6pCi/L

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

EPA’s reading of 1.6 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. Marshall County's median reported result, 2008 to 2017.

Interpret this reading

The data

Marshall County, At a glance

Marshall County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Marshall 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 Marshall County, 2023

Share of reported tests at or above 4 pCi/L, by year, Marshall County
Share of reported tests at or above 4 pCi/L, by year, Marshall County
YearShare of reported tests at or above 4 pCi/L
20220.0%
20230.0%

2023: 0.0%. Across these years the share ran from 0.0% to 0.0%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

Only 1 test was reported to CDC for Marshall County over 2023, and tests are often run on homes being sold or already suspected of a problem: so few describe neither the county nor this house.

Measured: CDC tracking data. Figure above: 2023. Measured data period: 2005 to 2023 (every CDC figure on file).

How to read these figures

Marshall County, Compared

Marshall County radon figures, compared

Calculated by Radon411

Marshall County's 138 reported tests over the 2008 to 2017 laboratory totals had a middle value of 1.6 pCi/L and a maximum of 36.8 pCi/L, and 18.1% reached 4 pCi/L. Tennessee as a whole (95 Tennessee counties, pooled) comes to 33.3%: 15.2 points higher than here.

The newest figure, in 2023, counts only 1 test (0.0% at or above 4 pCi/L), too few to compare, so this reading uses the 138-test figure.

Among its state's counties it ranks 61st of 80 Tennessee counties with 30 or more tests for the same period. Statewide for the same period, Jefferson County reported the highest share (56.8%) and Chester County the lowest (0.0%).

Below the action level, 82 tests (59.4%) came in under 2 pCi/L, against 42.4% statewide, and 31 tests (22.5%) fell between 2 and 4, against 24.3% statewide. The busiest year on file was 2022, with 3 tests reported; the quietest, 2023, had 1.

EPA's 1993 zone map puts Marshall County in Zone 1, a predicted county average above 4 pCi/L. USGS geology rates 100% of the county's land high radon potential.

Next door, the shares run from 15.3% in Rutherford County to 40.7% in Giles County, with Rutherford County below Marshall County.

Marshall County against Tennessee, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Marshall County
Marshall County13818.1%1.6 pCi/LThis county
Tennessee, pooled95 counties, pooled31,06633.3%Not pooled+15.2 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled+17.6 points
Jefferson Countyhighest in the state14656.8%4.7 pCi/L+38.7 points
Chester Countylowest in the state440.0%1.1 pCi/L−18.1 points
Giles County, TNborders it14040.7%3.3 pCi/L+22.6 points
Maury County, TNborders it50939.3%3.0 pCi/L+21.2 points
Williamson County, TNborders it3,41425.8%2.0 pCi/L+7.7 points
Bedford County, TNborders it12421.0%1.8 pCi/L+2.9 points
Lincoln County, TNborders it14920.8%1.9 pCi/L+2.7 points
Rutherford County, TNborders it1,20015.3%1.5 pCi/L−2.8 points
Where Marshall County's reported results fell, 2008 to 2017, laboratory, beside Tennessee and the United States
ResultMarshall County testsMarshall County shareTennessee shareU.S. shareAgainst Tennessee
Under 2 pCi/L8259.4%42.4%39.6%+17.0 points
2 to 4 pCi/L3122.5%24.3%24.7%−1.8 points
4 pCi/L and above2518.1%33.3%35.7%−15.2 points
Marshall County ranked among the 80 Tennessee counties with 30 or more tests, by share at or above 4 pCi/L, 2008 to 2017, laboratory
CountyRankTestsAt or above 4 pCi/LMedian
Lincoln County56 of 8014920.8%1.9 pCi/L
Sequatchie County57 of 805820.7%1.9 pCi/L
Wilson County58 of 8095920.2%1.7 pCi/L
Macon County59 of 806719.4%1.9 pCi/L
Hamilton County60 of 801,14819.3%1.7 pCi/L
Marshall County61 of 8013818.1%1.6 pCi/L
Henry County62 of 806016.7%1.6 pCi/L
Henderson County62 of 803016.7%1.6 pCi/L
Coffee County64 of 8020616.5%1.3 pCi/L
Lewis County65 of 805616.1%1.4 pCi/L
Rutherford County66 of 801,20015.3%1.5 pCi/L
Marshall County radon tests by year, against Tennessee's pooled share
YearTestsAt or above 4 pCi/LMedianHighestTennessee, pooledChange from the row before
202310.0%1.8 pCi/L1.8 pCi/L24.9%Level
202230.0%0.9 pCi/L0.9 pCi/L23.8%First on file

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

Marshall County, Geology

The ground under Marshall County

Predicted

USGS's geologic map puts all of Marshall County's mapped land in one class: high radon potential. All of it lies in the area the map calls Nashville Basin, to which USGS gives a radon index of 14, in the high band (12 to 17).

USGS's geologic areas under Marshall County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Nashville BasinMississippian Limestone.High14100%

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

Marshall County beside the ground around it

Marshall County has more high-potential ground than Tennessee as a whole: 100% of its land against 47.2%. Of the 6 counties that border it, none has as large a share of high-potential ground; Rutherford County comes nearest at 100%.

Share of land by USGS radon potential: Marshall County, the 6 counties bordering it and Tennessee
AreaEPA zoneLow potentialModerate potentialHigh potential
Marshall CountyZone 1NoneNone100%
Maury CountyZone 3NoneNone100%
Bedford CountyZone 1None2.2%97.8%
Lincoln CountyZone 1None29.8%70.2%
Giles CountyZone 1None0.1%99.9%
Williamson CountyZone 1None1.8%98.2%
Rutherford CountyZone 1NoneNone100%
Tennessee95 counties, pooled by land areaVaries30.5%22.3%47.2%

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

Local help

Marshall County, Local resources

Radon testing and mitigation in Marshall County

What Tennessee's program says
Phone
1-800-232-1139
Email
TDEC.Radon@tn.gov

What it means

Marshall County, Questions

Questions about radon in Marshall County

Are radon levels high in Marshall County?

In 2023, 0.0% of the radon tests reported to CDC for Marshall County, Tennessee were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.8 pCi/L. Of 80 Tennessee counties with 30 or more tests for the same period, 60 reported a higher share; pooled, the state comes to 33.3%.

Which counties border Marshall County?

Marshall County borders 6 counties: Maury County, Bedford County, Lincoln County, Giles County, Williamson County and Rutherford County.

Products

Marshall County, Products

Testing a home in Marshall County

In Marshall County, 18.1% of 138 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 33.3% pooled across Tennessee. In Zone 1 the year-round level in Marshall 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

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

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Marshall County, Bordering counties

Counties bordering Marshall County

Calculated by Radon411

Marshall County, Cities and towns

Cities and towns in Marshall County

Marshall County is growing: the Census Bureau puts it at 38,071 residents on July 1, 2025, up 10.5% from 34,467 in 2020. That works out to 101 people per square mile of land. Its largest town, Lewisburg, has 13,517 residents, 35.5% of the total. CDC's 138 reported tests for 2008 to 2017 work out to 3.6 per 1,000 residents (2025 estimate), close to Tennessee's 4.2.

From Lewisburg to Petersburg, CDC publishes no figure by town: each reads Marshall County's.

The cities and towns in Marshall County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Lewisburg13,517+9.5%35.5%
Chapel Hill1,905+10.7%5.0%
Cornersville1,385+10.7%3.6%
Petersburgextends beyond Marshall County562+6.8%Counted whole

4 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 Marshall County is counted whole, so it has no share.

Marshall County, Homes

Homes in Marshall County

Marshall County is a place of houses on their own lots: 83% of its 14,521 homes are detached single-family houses, against 68% across Tennessee. Half of its homes were built before 1991, close to Tennessee's 1986: 19% date from before 1960 and 32% from 2000 or later. Owners live in 77% of the occupied homes (Tennessee: 67%), so for most households a test and a fix are their own to order.

Homes in Marshall County, Tennessee, 2019 to 2023
HomesMarshall CountyTennessee
Housing units14,5213,095,472
Detached houses83%68%
In buildings of 5 or more4%14%
Mobile homes8%8%
Built before 196019%18%
Built since 200032%29%
Middle year built19911986
Owner-occupied77%67%

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