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Radon Levels in Buncombe County, North Carolina

EPA puts Buncombe County in Zone 1, its highest radon zone, and 38.0% of its 50 reported radon tests (2022) were at or above 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

    38.0%

    27.3 pts above NC

    Buncombe
    38.0%
    NC
    10.7%

    50 tests, 2022

  • Median result

    2.5pCi/L

    Below action level

    Buncombe
    2.5 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2022

  • Tests reported

    50

    4th of 4 by tests

    Buncombe
    50
    Pitt
    116

    Reported to CDC before any fix, 2022

  • 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 NC

    1 of 4

    Top quarter

    Buncombe
    38.0%
    Buncombe
    38.0%

    By share, of 4 with 30+ tests

Read a result for Buncombe County

Starts at Buncombe County's median, 2.5 pCi/L

2.5pCi/L

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

EPA’s reading of 2.5 pCi/L

Between 2 and 4 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 between 2 and 4 pCi/L. EPA recommends considering a fix when the level is between 2 and 4 pCi/L. Buncombe County's median reported result, 2022.

Interpret this readingWhat a fix costs

The data

Buncombe County, At a glance

Buncombe County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Buncombe 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: Moderate across 88% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Buncombe County, 2022

Share of reported tests at or above 4 pCi/L, by year, Buncombe County
Share of reported tests at or above 4 pCi/L, by year, Buncombe County
YearShare of reported tests at or above 4 pCi/L
201425.2%
202022.7%
202111.1%
202238.0%

2022: 38.0%. Across these years the share ran from 11.1% to 38.0%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

These are the 50 tests reported to CDC for Buncombe County over 2022, 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: 2022. Measured data period: 2005 to 2022 (every CDC figure on file).

How to read these figures

Buncombe County, Compared

Buncombe County radon figures, compared

Calculated by Radon411

In Buncombe County, about 4 in 10 reported tests in 2022 (19 of 50) were at or above EPA's action level. Against the national pool of 23.9%, the gap is 14.1 points higher. Across 57 North Carolina counties pooled together, 10.7% of tests reached that level, so Buncombe County runs 27.3 points above its state.

By share, Buncombe County is 1st of 4 North Carolina counties with 30 or more tests for the same period.

Year by year, 2014 opened at 25.2% and 2022 closed at 38.0% (up 12.8 points), with 2022 the high at 38.0%. Half the tests came in under 2.5 pCi/L and half over it; the single highest reached 66.0 pCi/L. Below the action level, 19 tests (38.0%) came in under 2 pCi/L, against 70.8% statewide, and 12 tests (24.0%) fell between 2 and 4, against 18.5% statewide.

Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 38.0% share point the same way here. USGS geology rates 88% of the county's land moderate radon potential.

The busiest year on file was 2020, with 1,141 tests reported; the quietest, 2022, had 50.

Share of reported tests at or above 4 pCi/L by year, Buncombe County against North Carolina2014 to 2022, years with 30 or more tests: Buncombe County 25.2% to 38.0%, the state's pooled share 10.7% in 2022.
Buncombe CountyNorth Carolina, pooled
Share of reported tests at or above 4 pCi/L by year, Buncombe County against North Carolina: data table
YearTestsBuncombe County, at or above 4 pCi/LNorth Carolina, pooled
201486025.2%21.9%
20201,14122.7%21.1%
202174211.1%14.9%
20225038.0%10.7%
Buncombe County against North Carolina, the United States and nearby counties, 2022
AreaTestsAt or above 4 pCi/LMedianDifference from Buncombe County
Buncombe County5038.0%2.5 pCi/LThis county
North Carolina, pooled57 counties, pooled59010.7%Not pooled−27.3 points
United States, pooled853 counties, pooled333,14023.9%Not pooled−14.1 points
Wake Countyhighest in the state882.3%0.1 pCi/L−35.7 points
Pitt Countylowest in the state1160.9%1.0 pCi/L−37.1 points
Henderson County, NCborders it1040.0%2.0 pCi/L+2.0 points
Haywood County, NCborders it185.6%1.0 pCi/L−32.4 points
Transylvania County, NCborders it205.0%1.0 pCi/L−33.0 points
Rutherford County, NCborders it10.0%1.0 pCi/L−38.0 points
Madison County, NCborders it50.0%0.1 pCi/L−38.0 points
Where Buncombe County's reported results fell, 2022, beside North Carolina and the United States
ResultBuncombe County testsBuncombe County shareNorth Carolina shareU.S. shareAgainst North Carolina
Under 2 pCi/L1938.0%70.8%54.5%−32.8 points
2 to 4 pCi/L1224.0%18.5%21.7%+5.5 points
4 pCi/L and above1938.0%10.7%23.9%+27.3 points
Buncombe County ranked among the 4 North Carolina counties with 30 or more tests, by share at or above 4 pCi/L, 2022
CountyRankTestsAt or above 4 pCi/LMedian
Buncombe County1 of 45038.0%2.5 pCi/L
Wake County2 of 4882.3%0.1 pCi/L
Wayne County3 of 4671.5%1.0 pCi/L
Pitt County4 of 41160.9%1.0 pCi/L
Buncombe County radon tests by year, against North Carolina's pooled share
YearTestsAt or above 4 pCi/LMedianHighestNorth Carolina, pooledChange from the row before
20225038.0%2.5 pCi/L66.0 pCi/L10.7%+26.9 points
202174211.1%1.0 pCi/L26.0 pCi/L14.9%−11.6 points
20201,14122.7%1.4 pCi/L45.3 pCi/L21.1%−2.5 points
201486025.2%2.0 pCi/L49.4 pCi/L21.9%First on file

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

Buncombe County, Geology

The ground under Buncombe County

Predicted

Most of the ground under Buncombe County is one class on USGS's geologic map: 88.0% of its land is moderate radon potential, with 12.0% high. The map puts 87.5% of Buncombe County in the area it calls Blue Ridge and 6.3% in Chauga Belt, with one smaller area beside them. USGS gives the first a radon index of 10, in the moderate band (9 to 11), and the second 12, in the high band (12 to 17).

USGS's geologic areas under Buncombe County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Blue RidgeGranite, pegmatite, monazite, schist, and gneiss.Moderate1087.5%
Chauga BeltMonzonitic to granodioritic gneiss.High126.3%
Brevard Fault ZoneSchist, marble and phyllonite.High125.8%

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

Buncombe County beside the ground around it

Buncombe County has more high-potential ground than North Carolina as a whole: 12.0% of its land against 1.3%. Of the 7 counties that border it, 3 have more high-potential ground, Henderson County the most at 52.6%.

Share of land by USGS radon potential: Buncombe County, the 7 counties bordering it and North Carolina
AreaEPA zoneLow potentialModerate potentialHigh potential
Buncombe CountyZone 1None88.0%12.0%
Madison CountyZone 2None99.9%0.1%
Henderson CountyZone 1None47.4%52.6%
Yancey CountyZone 2None100%None
Haywood CountyZone 2None100%None
McDowell CountyZone 2None75.1%24.9%
Transylvania CountyZone 1None48.0%52.0%
Rutherford CountyZone 2None99.7%0.3%
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

Buncombe County, Local resources

Radon testing and mitigation in Buncombe 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

Buncombe County, Questions

Questions about radon in Buncombe County

Are radon levels high in Buncombe County?

In 2022, 38.0% of the radon tests reported to CDC for Buncombe County, North Carolina were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.5 pCi/L. Of 4 North Carolina counties with 30 or more tests for the same period, none reported a higher share; pooled, the state comes to 10.7%.

Which counties border Buncombe County?

Buncombe County borders 7 counties: Madison County, Henderson County, Yancey County, Haywood County, McDowell County, Transylvania County and Rutherford County.

Products

Buncombe County, Products

Testing a home in Buncombe County

In Buncombe County, 38.0% of 50 tests reported to CDC in 2022 reached 4 pCi/L, against 10.7% pooled across North Carolina. In Zone 1 the year-round level in Buncombe 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

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

Explore

Buncombe County, Bordering counties

Counties bordering Buncombe County

Calculated by Radon411

Buncombe County, Cities and towns

Cities and towns in Buncombe County

The Census Bureau estimates 277,417 residents in Buncombe County for July 1, 2025, 7,714 more than in 2020 (+2.9%). That works out to 423 people per square mile of land. Its largest town, Asheville, has 93,523 residents, 33.7% of the total. Together its 6 incorporated places hold 42.4% of those residents; the other 57.6% live outside any of them. Testing is reported here more often than across the state: CDC's 50 reported tests for 2022 come to 0.2 for every 1,000 residents (2025 estimate), against 0.1 for North Carolina.

From Asheville to Montreat, CDC publishes no figure by town: each reads Buncombe County's.

The cities and towns in Buncombe County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Asheville93,523−0.9%33.7%
Black Mountain8,491+0.6%3.1%
Woodfin8,229+3.1%3.0%
Weaverville4,790+4.3%1.7%
Biltmore Forest1,469+4.6%0.5%
Montreat1,024−1.0%0.4%

6 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).

Buncombe County, Homes

Homes in Buncombe County

Of Buncombe County's 132,191 homes, 64% are detached houses, against 65% across North Carolina; 16% are in buildings of five or more homes. Half of its homes were built before 1989, close to North Carolina's 1990: 21% date from before 1960 and 32% from 2000 or later. 64% 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 Buncombe County, North Carolina, 2019 to 2023
HomesBuncombe CountyNorth Carolina
Housing units132,1914,815,195
Detached houses64%65%
In buildings of 5 or more16%14%
Mobile homes12%11%
Built before 196021%14%
Built since 200032%33%
Middle year built19891990
Owner-occupied64%66%

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