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Radon Levels in McDowell County, North Carolina

EPA puts McDowell County in Zone 2, its middle radon zone, and 35.2% of its 54 reported radon tests (2021) 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

How to test this homeFind a certified tester

  • Share at 4+ pCi/L

    35.2%

    20.3 pts above NC

    McDowell
    35.2%
    NC
    14.9%

    54 tests, 2021

  • Median result

    2.0pCi/L

    Below action level

    McDowell
    2.0 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2021

  • Tests reported

    54

    27th of 36 by tests

    McDowell
    54
    Buncombe
    742

    Reported to CDC before any fix, 2021

  • 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

    3 of 36

    Top quarter

    McDowell
    35.2%
    Ashe
    48.5%

    By share, of 36 with 30+ tests

Read a result for McDowell County

Starts at McDowell County's median, 2.0 pCi/L

2.0pCi/L

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

EPA’s reading of 2.0 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. McDowell County's median reported result, 2021.

Interpret this readingWhat a fix costs

The data

McDowell County, At a glance

McDowell County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

McDowell 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 75% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for McDowell County, 2021

Share of reported tests at or above 4 pCi/L, by year, McDowell County
Share of reported tests at or above 4 pCi/L, by year, McDowell County
YearShare of reported tests at or above 4 pCi/L
201434.8%
202034.2%
202135.2%

2021: 35.2%. Across these years the share ran from 34.2% to 35.2%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

These are the 54 tests reported to CDC for McDowell County over 2021, 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: 2021. Measured data period: 2005 to 2021 (every CDC figure on file).

How to read these figures

McDowell County, Compared

McDowell County radon figures, compared

Calculated by Radon411

In McDowell County, about 4 in 10 reported tests in 2021 (19 of 54) were at or above EPA's action level. Against the national pool of 24.4%, the gap is 10.8 points higher. Across 82 North Carolina counties pooled together, 14.9% of tests reached that level, so McDowell County runs 20.3 points above its state.

Of 4 neighbours with a figure, none reported a larger share at or above 4 pCi/L; the spread is 11.1% (Buncombe County) to 32.3% (Yancey County). By share, McDowell County is 3rd of 36 North Carolina counties with 30 or more tests for the same period.

Year by year, 2014 opened at 34.8% and 2021 closed at 35.2% (about level), with 2021 the high at 35.2%. Half the tests came in under 2.0 pCi/L and half over it; the single highest reached 14.0 pCi/L. Below the action level, 26 tests (48.1%) came in under 2 pCi/L, against 65.1% statewide, and 9 tests (16.7%) fell between 2 and 4, against 20.0% statewide.

Zone 2 on EPA's map (predicted average between 2 and 4 pCi/L) and a 35.2% share point the same way here. USGS geology rates 75% of the county's land moderate radon potential.

The busiest year on file was 2014, with 112 tests reported; the quietest, 2021, had 54.

Share of reported tests at or above 4 pCi/L by year, McDowell County against North Carolina2014 to 2021, years with 30 or more tests: McDowell County 34.8% to 35.2%, the state's pooled share 14.9% in 2021.
McDowell CountyNorth Carolina, pooled
Share of reported tests at or above 4 pCi/L by year, McDowell County against North Carolina: data table
YearTestsMcDowell County, at or above 4 pCi/LNorth Carolina, pooled
201411234.8%21.9%
20207634.2%21.1%
20215435.2%14.9%
McDowell County against North Carolina, the United States and nearby counties, 2021
AreaTestsAt or above 4 pCi/LMedianDifference from McDowell County
McDowell County5435.2%2.0 pCi/LThis county
North Carolina, pooled82 counties, pooled6,60314.9%Not pooled−20.3 points
United States, pooled807 counties, pooled344,60424.4%Not pooled−10.8 points
Ashe Countyhighest in the state3348.5%3.0 pCi/L+13.3 points
Alamance Countylowest in the state560.0%0.1 pCi/L−35.2 points
Yancey County, NCborders it3132.3%1.0 pCi/L−2.9 points
Avery County, NCborders it2832.1%2.0 pCi/L−3.1 points
Burke County, NCborders it11721.4%1.0 pCi/L−13.8 points
Rutherford County, NCborders it4216.7%1.5 pCi/L−18.5 points
Mitchell County, NCborders it2015.0%1.0 pCi/L−20.2 points
Buncombe County, NCborders it74211.1%1.0 pCi/L−24.1 points
Where McDowell County's reported results fell, 2021, beside North Carolina and the United States
ResultMcDowell County testsMcDowell County shareNorth Carolina shareU.S. shareAgainst North Carolina
Under 2 pCi/L2648.1%65.1%54.4%−17.0 points
2 to 4 pCi/L916.7%20.0%21.2%−3.3 points
4 pCi/L and above1935.2%14.9%24.4%+20.3 points
McDowell County ranked among the 36 North Carolina counties with 30 or more tests, by share at or above 4 pCi/L, 2021
CountyRankTestsAt or above 4 pCi/LMedian
Ashe County1 of 363348.5%3.0 pCi/L
Wilkes County2 of 363441.2%2.0 pCi/L
McDowell County3 of 365435.2%2.0 pCi/L
Yancey County4 of 363132.3%1.0 pCi/L
Henderson County5 of 3645128.6%2.0 pCi/L
Transylvania County6 of 3635528.5%2.0 pCi/L
Polk County7 of 364926.5%2.0 pCi/L
Cherokee County8 of 365625.0%2.0 pCi/L
Haywood County9 of 3616923.1%1.0 pCi/L
Burke County10 of 3611721.4%1.0 pCi/L
Jackson County11 of 3623721.1%1.0 pCi/L
McDowell County radon tests by year, against North Carolina's pooled share
YearTestsAt or above 4 pCi/LMedianHighestNorth Carolina, pooledChange from the row before
20215435.2%2.0 pCi/L14.0 pCi/L14.9%+1.0 points
20207634.2%1.0 pCi/L23.0 pCi/L21.1%−0.6 points
201411234.8%2.0 pCi/L43.0 pCi/L21.9%First on file

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

McDowell County, Geology

The ground under McDowell County

Predicted

Most of the ground under McDowell County is one class on USGS's geologic map: 75.1% of its land is moderate radon potential, with 24.9% high. The map puts 42.1% of McDowell County in the area it calls Blue Ridge and 32.9% in Inner Piedmont Belt, with 2 smaller areas beside them. USGS gives the first a radon index of 10 and the second 11, both in the moderate band (9 to 11).

USGS's geologic areas under McDowell County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Blue RidgeGranite, pegmatite, monazite, schist, and gneiss.Moderate1042.1%
Inner Piedmont BeltProterozoic through Cambrian biotite gneiss and schist, and mica schist.Moderate1132.9%
Chauga BeltMonzonitic to granodioritic gneiss.High1220.3%
Brevard Fault ZoneSchist, marble and phyllonite.High124.6%

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

McDowell County beside the ground around it

McDowell County has more high-potential ground than North Carolina as a whole: 24.9% of its land against 1.3%. Of the 6 counties that border it, none has as large a share of high-potential ground; Buncombe County comes nearest at 12.0%.

Share of land by USGS radon potential: McDowell County, the 6 counties bordering it and North Carolina
AreaEPA zoneLow potentialModerate potentialHigh potential
McDowell CountyZone 2None75.1%24.9%
Yancey CountyZone 2None100%None
Mitchell CountyZone 1None99.9%0.1%
Burke CountyZone 2None94.2%5.8%
Avery CountyZone 2None100%None
Rutherford CountyZone 2None99.7%0.3%
Buncombe CountyZone 1None88.0%12.0%
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

McDowell County, Local resources

Radon testing and mitigation in McDowell 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

McDowell County, Questions

Questions about radon in McDowell County

Are radon levels high in McDowell County?

In 2021, 35.2% of the radon tests reported to CDC for McDowell County, North Carolina were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.0 pCi/L. Of 36 North Carolina counties with 30 or more tests for the same period, 2 reported a higher share; pooled, the state comes to 14.9%.

Which counties border McDowell County?

McDowell County borders 6 counties: Yancey County, Mitchell County, Burke County, Avery County, Rutherford County and Buncombe County.

Products

McDowell County, Products

Testing a home in McDowell County

In McDowell County, 35.2% of 54 tests reported to CDC in 2021 reached 4 pCi/L, against 14.9% pooled across North Carolina. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in McDowell County; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for McDowell County homes, compared

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McDowell County, Bordering counties

Counties bordering McDowell County

Calculated by Radon411

McDowell County, Cities and towns

Cities and towns in McDowell County

The Census Bureau estimates 45,198 residents in McDowell County for July 1, 2025, 644 more than in 2020 (+1.4%). That works out to 103 people per square mile of land. No town dominates: Marion, the largest, has 7,440 residents, 16.5% of the total. Together its 2 incorporated places hold 18.2% of those residents; the other 81.8% live outside any of them. Testing is reported here more often than across the state: CDC's 54 reported tests for 2021 come to 1.2 for every 1,000 residents (2025 estimate), against 0.6 for North Carolina.

From Marion to Old Fort, CDC publishes no figure by town: each reads McDowell County's.

The cities and towns in McDowell County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Marion7,440−2.7%16.5%
Old Fort797−0.9%1.8%

2 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).

McDowell County, Homes

Homes in McDowell County

Of McDowell County's 21,475 homes, 69% are detached houses, against 65% across North Carolina; 26% are mobile homes. Half of its homes were built before 1983, close to North Carolina's 1990: 20% date from before 1960 and 24% from 2000 or later. 74% 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 McDowell County, North Carolina, 2019 to 2023
HomesMcDowell CountyNorth Carolina
Housing units21,4754,815,195
Detached houses69%65%
In buildings of 5 or more3%14%
Mobile homes26%11%
Built before 196020%14%
Built since 200024%33%
Middle year built19831990
Owner-occupied74%66%

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