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Radon Levels in Franklin County, North Carolina

EPA puts Franklin County in Zone 2, its middle radon zone, and only 11 radon tests from it are on file with CDC (2021). 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

    19.1%

    3.5 pts below NC

    Franklin
    19.1%
    NC
    22.6%

    204 tests, 2008 to 2017

  • Median result

    1.4pCi/L

    Below action level

    Franklin
    1.4 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    204

    46th of 75 by tests

    Franklin
    204
    Wake
    9,694

    Reported to CDC before any fix, 2008 to 2017

  • EPA radon zone

    Zone 2

    Moderate potential

    1. 1
    2. Zone 2
    3. 3

    1 highest, 3 lowest

    EPA predicts 2 to 4 pCi/L indoors

  • Rank in NC

    40 of 75

    Middle half

    Franklin
    19.1%
    Transylvania
    47.8%

    By share, of 75 with 30+ tests

Read a result for Franklin County

Starts at Franklin County's median, 1.4 pCi/L

1.4pCi/L

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

EPA’s reading of 1.4 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. Franklin County's median reported result, 2008 to 2017.

Interpret this reading

The data

Franklin County, At a glance

Franklin County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

Franklin County is a county: EPA's forecast for it as a whole is an average indoor of 2 to 4 pCi/L (75 to 150 Bq/m³). It describes no single address, and homes above EPA's are found in every zone, this one included.

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

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Franklin County, 2021

Share of reported tests at or above 4 pCi/L, by year, Franklin County
Share of reported tests at or above 4 pCi/L, by year, Franklin County
YearShare of reported tests at or above 4 pCi/L
201423.3%
20205.4%
20219.1%

2021: 9.1%. Across these years the share ran from 5.4% to 23.3%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

Only 11 tests were reported to CDC for Franklin County over 2021, 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: 2021. Measured data period: 2005 to 2021 (every CDC figure on file).

How to read these figures

Franklin County, Compared

Franklin County radon figures, compared

Calculated by Radon411

Franklin County's 204 reported tests over the 2008 to 2017 laboratory totals had a middle value of 1.4 pCi/L and a maximum of 25.9 pCi/L, and 19.1% reached 4 pCi/L. North Carolina as a whole (99 North Carolina counties, pooled) comes to 22.6%: 3.5 points higher than here.

The newest figure, in 2021, counts only 11 tests (9.1% at or above 4 pCi/L), too few to compare, so this reading uses the 204-test figure.

Among its state's counties it ranks 40th of 75 North Carolina counties with 30 or more tests for the same period. Statewide for the same period, Transylvania County reported the highest share (47.8%) and Nash County the lowest (0.0%).

Below the action level, 130 tests (63.7%) came in under 2 pCi/L, against 55.6% statewide, and 35 tests (17.2%) fell between 2 and 4, against 21.8% statewide. The busiest year on file was 2020, with 56 tests reported; the quietest, 2021, had 11.

EPA's 1993 zone map puts Franklin County in Zone 2, a predicted county average between 2 and 4 pCi/L. USGS geology rates 100% of the county's land moderate radon potential.

Next door, the shares run from 0.0% in Nash County to 42.7% in Warren County, with Vance County, Granville County and Wake County below Franklin County.

Franklin County against North Carolina, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Franklin County
Franklin County20419.1%1.4 pCi/LThis county
North Carolina, pooled99 counties, pooled73,13922.6%Not pooled+3.5 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled+16.6 points
Transylvania Countyhighest in the state3,86247.8%3.7 pCi/L+28.7 points
Columbus Countylowest in the state310.0%0.1 pCi/L−19.1 points
Warren County, NCborders it8242.7%3.0 pCi/L+23.6 points
Halifax County, NCborders it5942.4%2.6 pCi/L+23.3 points
Vance County, NCborders it10914.7%1.5 pCi/L−4.4 points
Granville County, NCborders it15310.5%0.8 pCi/L−8.6 points
Wake County, NCborders it9,6949.6%1.0 pCi/L−9.5 points
Johnston County, NCborders it6688.2%0.7 pCi/L−10.9 points
Nash County, NCborders it300.0%0.2 pCi/L−19.1 points
Where Franklin County's reported results fell, 2008 to 2017, laboratory, beside North Carolina and the United States
ResultFranklin County testsFranklin County shareNorth Carolina shareU.S. shareAgainst North Carolina
Under 2 pCi/L13063.7%55.6%39.6%+8.1 points
2 to 4 pCi/L3517.2%21.8%24.7%−4.6 points
4 pCi/L and above3919.1%22.6%35.7%−3.5 points
Franklin County ranked among the 75 North Carolina counties with 30 or more tests, by share at or above 4 pCi/L, 2008 to 2017, laboratory
CountyRankTestsAt or above 4 pCi/LMedian
Catawba County35 of 751,25924.8%2.0 pCi/L
Iredell County36 of 751,14621.8%1.8 pCi/L
Stokes County37 of 7559221.6%1.8 pCi/L
Montgomery County38 of 7510320.4%1.5 pCi/L
Moore County39 of 759919.2%1.3 pCi/L
Franklin County40 of 7520419.1%1.4 pCi/L
Gaston County41 of 7559319.1%1.5 pCi/L
Rowan County42 of 7562617.7%1.4 pCi/L
Davie County43 of 7569417.4%1.7 pCi/L
Person County44 of 7519017.4%1.3 pCi/L
Macon County45 of 751,35417.1%1.4 pCi/L
Franklin County radon tests by year, against North Carolina's pooled share
YearTestsAt or above 4 pCi/LMedianHighestNorth Carolina, pooledChange from the row before
2021119.1%1.0 pCi/L6.0 pCi/L14.9%+3.7 points
2020565.4%1.3 pCi/L22.7 pCi/L21.1%−17.9 points
20144323.3%1.0 pCi/L8.0 pCi/L21.9%First on file

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

Franklin County, Geology

The ground under Franklin County

Predicted

Most of the ground under Franklin County is one class on USGS's geologic map: 99.8% of its land is moderate radon potential, with 0.2% low. All of it lies in the area the map calls Raleigh Belt, to which USGS gives a radon index of 11, in the moderate band (9 to 11).

USGS's geologic areas under Franklin County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Raleigh BeltProterozoic through Cambrian biotite gneiss and mica schist.Moderate1199.8%

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

Franklin County beside the ground around it

Across North Carolina 1.3% of the land is rated high; none of Franklin County's is. Of the 7 counties that border it, 1 has more moderate-potential ground, Warren County the most at 100%.

Share of land by USGS radon potential: Franklin County, the 7 counties bordering it and North Carolina
AreaEPA zoneLow potentialModerate potentialHigh potential
Franklin CountyZone 20.2%99.8%None
Nash CountyZone 386.8%13.2%None
Vance CountyZone 236.7%63.3%None
Warren CountyZone 2None100%None
Wake CountyZone 220.6%79.4%None
Granville CountyZone 387.8%12.2%None
Johnston CountyZone 369.1%30.9%None
Halifax CountyZone 389.8%10.2%None
North Carolina100 counties, pooled by land areaVaries64.8%33.0%1.3%

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

Local help

Franklin County, Local resources

Radon testing and mitigation in Franklin County

What North Carolina's program says
Licensing of radon professionals
The North Carolina Radon Program is presently developing a Radon Proficiency Program as directed by Session Law 2023-91 House Bill 782 .

What it means

Franklin County, Questions

Questions about radon in Franklin County

Are radon levels high in Franklin County?

In 2021, 9.1% of the radon tests reported to CDC for Franklin County, North Carolina were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.0 pCi/L. Of 75 North Carolina counties with 30 or more tests for the same period, 39 reported a higher share; pooled, the state comes to 22.6%.

Which counties border Franklin County?

Franklin County borders 7 counties: Nash County, Vance County, Warren County, Wake County, Granville County, Johnston County and Halifax County.

Products

Franklin County, Products

Testing a home in Franklin County

In Franklin County, 19.1% of 204 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 22.6% pooled across North Carolina. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Franklin County; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Franklin County homes, compared

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Franklin County, Bordering counties

Counties bordering Franklin County

Calculated by Radon411

Franklin County, Cities and towns

Cities and towns in Franklin County

Franklin County is growing: the Census Bureau puts it at 82,037 residents on July 1, 2025, up 18.8% from 69,029 in 2020. That works out to 167 people per square mile of land. Wake Forest, the largest place on its list (58,147 residents in all), extends beyond Franklin County, so no share of the total is worked out for it. Reported testing is thin here: 204 tests over 2008 to 2017, or 2.5 for every 1,000 residents (2025 estimate), where North Carolina as a whole comes to 6.5.

From Wake Forest to Bunn, CDC publishes no figure by town: each reads Franklin County's.

The cities and towns in Franklin County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Wake Forestextends beyond Franklin County58,147+16.9%Counted whole
Louisburg3,480+11.8%4.2%
Franklinton2,890+17.0%3.5%
Youngsville2,461+17.5%3.0%
Bunn391+17.1%0.5%

5 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 Franklin County is counted whole, so it has no share.

Franklin County, Homes

Homes in Franklin County

Of Franklin County's 30,790 homes, 72% are detached houses, against 65% across North Carolina; 23% are mobile homes. Half of its homes were built before 1995, close to North Carolina's 1990: 13% date from before 1960 and 40% from 2000 or later. Owners live in 78% of the occupied homes (North Carolina: 66%), so for most households a test and a fix are their own to order.

Homes in Franklin County, North Carolina, 2019 to 2023
HomesFranklin CountyNorth Carolina
Housing units30,7904,815,195
Detached houses72%65%
In buildings of 5 or more3%14%
Mobile homes23%11%
Built before 196013%14%
Built since 200040%33%
Middle year built19951990
Owner-occupied78%66%

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