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Radon Levels in Durham County, North Carolina

EPA puts Durham County in Zone 3, its lowest radon zone, and only 10 radon tests from it are on file with CDC (2022). 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

    4.3%

    18.3 pts below NC

    Durham
    4.3%
    NC
    22.6%

    1,570 tests, 2008 to 2017

  • Median result

    0.7pCi/L

    Below action level

    Durham
    0.7 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    1,570

    9th of 75 by tests

    Durham
    1,570
    Wake
    9,694

    Reported to CDC before any fix, 2008 to 2017

  • EPA radon zone

    Zone 3

    Lower potential

    1. 1
    2. 2
    3. Zone 3

    1 highest, 3 lowest

    EPA predicts under 2 pCi/L indoors

  • Rank in NC

    60 of 75

    Lowest quarter

    Durham
    4.3%
    Transylvania
    47.8%

    By share, of 75 with 30+ tests

Read a result for Durham County

Starts at Durham County's median, 0.7 pCi/L

0.7pCi/L

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

EPA’s reading of 0.7 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. Durham County's median reported result, 2008 to 2017.

Interpret this reading

The data

Durham County, At a glance

Durham County at a glance

Predicted: EPA radon zone

EPA Zone 3: lower predicted potential

is EPA's lowest class, and its forecast for Durham County as a whole is an average indoor of less than 2 pCi/L (less than 75 Bq/m³). A low zone clears no address in it: homes above EPA's turn up in all three zones.

USGS geologic potential: Low across 97% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Durham County, 2022

Share of reported tests at or above 4 pCi/L, by year, Durham County
Share of reported tests at or above 4 pCi/L, by year, Durham County
YearShare of reported tests at or above 4 pCi/L
20145.7%
20205.3%
20218.3%
20220.0%

2022: 0.0%. Across these years the share ran from 0.0% to 8.3%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

Only 10 tests were reported to CDC for Durham County over 2022, 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: 2022. Measured data period: 2005 to 2022 (every CDC figure on file).

How to read these figures

Durham County, Compared

Durham County radon figures, compared

Calculated by Radon411

Only 67 of 1,570 radon tests reported for Durham County over the 2008 to 2017 laboratory totals reached 4 pCi/L (4.3%). The median result, 0.7 pCi/L, sits below 2, well under EPA's 4 pCi/L action level, and the top reported result was 15.4 pCi/L.

The newest figure, in 2022, counts only 10 tests (0.0% at or above 4 pCi/L), too few to compare, so this reading uses the 1,570-test figure.

Across 99 North Carolina counties pooled together, 22.6% of tests reached that level, so Durham County runs 18.3 points below its state. Against the national pool of 35.7%, the gap is 31.4 points lower. Its place in the state: 60th of 75 North Carolina counties with 30 or more tests for the same period.

Zone 3 on EPA's map (predicted average under 2 pCi/L) and a 4.3% share point the same way here. Of 5 neighbours with a figure, all 5 reported a larger share at or above 4 pCi/L; the spread is 9.6% (Wake County) to 17.4% (Person County).

Below the action level, 1,316 tests (83.8%) came in under 2 pCi/L, against 55.6% statewide, and 187 tests (11.9%) fell between 2 and 4, against 21.8% statewide. Over 3 years of annual figures the share rose 2.6 points, from 5.7% in 2014 to 8.3% in 2021; its peak was 8.3% in 2021. USGS geology rates 97% of the county's land low radon potential.

The busiest year on file was 2014, with 246 tests reported; the quietest, 2022, had 10.

Share of reported tests at or above 4 pCi/L by year, Durham County against North Carolina2014 to 2021, years with 30 or more tests: Durham County 5.7% to 8.3%, the state's pooled share 14.9% in 2021.
Durham CountyNorth Carolina, pooled
Share of reported tests at or above 4 pCi/L by year, Durham County against North Carolina: data table
YearTestsDurham County, at or above 4 pCi/LNorth Carolina, pooled
20142465.7%21.9%
20201885.3%21.1%
2021728.3%14.9%
Durham County against North Carolina, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Durham County
Durham County1,5704.3%0.7 pCi/LThis county
North Carolina, pooled99 counties, pooled73,13922.6%Not pooled+18.3 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled+31.4 points
Transylvania Countyhighest in the state3,86247.8%3.7 pCi/L+43.5 points
Nash Countylowest in the state300.0%0.2 pCi/L−4.3 points
Person County, NCborders it19017.4%1.3 pCi/L+13.1 points
Chatham County, NCborders it58710.9%1.1 pCi/L+6.6 points
Orange County, NCborders it1,09510.7%1.1 pCi/L+6.4 points
Granville County, NCborders it15310.5%0.8 pCi/L+6.2 points
Wake County, NCborders it9,6949.6%1.0 pCi/L+5.3 points
Where Durham County's reported results fell, 2008 to 2017, laboratory, beside North Carolina and the United States
ResultDurham County testsDurham County shareNorth Carolina shareU.S. shareAgainst North Carolina
Under 2 pCi/L1,31683.8%55.6%39.6%+28.2 points
2 to 4 pCi/L18711.9%21.8%24.7%−9.9 points
4 pCi/L and above674.3%22.6%35.7%−18.3 points
Durham 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
Mecklenburg County55 of 753,7538.5%0.9 pCi/L
Johnston County56 of 756688.2%0.7 pCi/L
Wayne County57 of 75498.2%0.6 pCi/L
Guilford County58 of 756,8707.9%0.9 pCi/L
Randolph County59 of 754227.1%0.9 pCi/L
Durham County60 of 751,5704.3%0.7 pCi/L
Robeson County61 of 75533.8%0.8 pCi/L
Alamance County62 of 755203.7%0.5 pCi/L
New Hanover County63 of 751173.4%0.1 pCi/L
Scotland County64 of 75313.2%1.0 pCi/L
Onslow County65 of 751882.7%0.5 pCi/L
Durham County radon tests by year, against North Carolina's pooled share
YearTestsAt or above 4 pCi/LMedianHighestNorth Carolina, pooledChange from the row before
2022100.0%0.1 pCi/L3.0 pCi/L10.7%−8.3 points
2021728.3%0.1 pCi/L5.0 pCi/L14.9%+3.0 points
20201885.3%0.6 pCi/L24.1 pCi/L21.1%−0.4 points
20142465.7%0.1 pCi/L15.0 pCi/L21.9%First on file

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

Durham County, Geology

The ground under Durham County

Predicted

Most of the ground under Durham County is one class on USGS's geologic map: 96.7% of its land is low radon potential, with 3.3% moderate. The map puts 68.8% of Durham County in the area it calls Sanford-Durham Sub-Basins and 27.9% in Carolina Slate Belt, with one smaller area beside them. USGS gives the first a radon index of 8 and the second 6, both in the low band (5 to 8).

USGS's geologic areas under Durham County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Sanford-Durham Sub-BasinsArkosic sandstone, siltstone and conglomerate.Low868.8%
Carolina Slate BeltFelsic metavolcanics, intermediate volcanics, metamudstone, argillite, and epiclastic rocks.Low627.9%
Raleigh BeltProterozoic through Cambrian biotite gneiss and mica schist.Moderate113.3%

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

Durham County beside the ground around it

Across North Carolina 1.3% of the land is rated high; none of Durham County's is. Of the 5 counties that border it, 3 have more moderate-potential ground, Wake County the most at 79.4%.

Share of land by USGS radon potential: Durham County, the 5 counties bordering it and North Carolina
AreaEPA zoneLow potentialModerate potentialHigh potential
Durham CountyZone 396.7%3.3%None
Orange CountyZone 3100%NoneNone
Wake CountyZone 220.6%79.4%None
Granville CountyZone 387.8%12.2%None
Person CountyZone 387.2%12.8%None
Chatham CountyZone 398.6%1.4%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

Durham County, Local resources

Radon testing and mitigation in Durham County

Listed radon professionals by town: Morrisville

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

Durham County, Questions

Questions about radon in Durham County

Are radon levels high in Durham County?

In 2022, 0.0% of the radon tests reported to CDC for Durham County, North Carolina were at or above 4 pCi/L, and the median reported pre-mitigation result was 0.1 pCi/L. Of 75 North Carolina counties with 30 or more tests for the same period, 59 reported a higher share; pooled, the state comes to 22.6%.

Which counties border Durham County?

Durham County borders 5 counties: Orange County, Wake County, Granville County, Person County and Chatham County.

Products

Durham County, Products

Testing a home in Durham County

In Durham County, 4.3% of 1,570 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 22.6% pooled across North Carolina. Zone 3 is the lowest label, yet homes at or above 4 pCi/L occur in every zone: a short-term kit (2 to 90 days) is the quick first check in Durham County.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Durham County homes, compared

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Durham County, Bordering counties

Counties bordering Durham County

Calculated by Radon411

Durham County, Cities and towns

Cities and towns in Durham County

Durham County is growing: the Census Bureau puts it at 347,240 residents on July 1, 2025, up 7.7% from 322,465 in 2020. Packed into its land, that is 1,212 people per square mile. Raleigh, the largest place on its list (506,306 residents in all), extends beyond Durham County, so no share of the total is worked out for it. CDC's 1,570 reported tests for 2008 to 2017 work out to 4.5 per 1,000 residents (2025 estimate), close to North Carolina's 6.5.

From Raleigh to Morrisville, CDC publishes no figure by town: each reads Durham County's.

The cities and towns in Durham County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Raleighextends beyond Durham County506,306+8.6%Counted whole
Durhamextends beyond Durham County305,561+8.5%Counted whole
Chapel Hillextends beyond Durham County63,565+11.4%Counted whole
Morrisvilleextends beyond Durham County32,466+7.8%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 Durham County is counted whole, so it has no share.

Durham County, Homes

Homes in Durham County

Fewer than six in ten of Durham County's 149,150 homes are detached houses (55%, against 65% across North Carolina); the rest are attached, in shared buildings or mobile. Half of its homes were built before 1993, close to North Carolina's 1990: 14% date from before 1960 and 39% from 2000 or later. 55% of occupied homes are lived in by their owner (North Carolina: 66%); in the rest a tenant can run a test, but a fix is the landlord's to make.

Homes in Durham County, North Carolina, 2019 to 2023
HomesDurham CountyNorth Carolina
Housing units149,1504,815,195
Detached houses55%65%
In buildings of 5 or more28%14%
Mobile homes1%11%
Built before 196014%14%
Built since 200039%33%
Middle year built19931990
Owner-occupied55%66%

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