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Radon Levels in Carroll County, Virginia

EPA puts Carroll County in Zone 2, its middle radon zone, and high results are common there: 61.8% of the 89 radon tests reported to CDC (2008 to 2017, laboratory totals) came back 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

    61.8%

    31.4 pts above VA

    Carroll
    61.8%
    Virginia
    30.4%

    89 tests, 2008 to 2017

  • Median result

    5.0pCi/L

    Action level reached

    Carroll
    5.0 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    89

    61st of 84 by tests

    Carroll
    89
    Fairfax
    8,657

    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 Virginia

    3 of 84

    Top quarter

    Carroll
    61.8%
    Russell
    67.3%

    By share, of 84 with 30+ tests

Read a result for Carroll County

Starts at Carroll County's median, 5.0 pCi/L

5.0pCi/L

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

EPA’s reading of 5.0 pCi/L

At or above 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 at or above 4 pCi/L. EPA recommends fixing a home when the radon level is 4 pCi/L or higher. Carroll County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Carroll County, At a glance

Carroll County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

Carroll 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 96% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Carroll County, 2008 to 2017, laboratory

Reported results by concentration band, Carroll County, 2008 to 2017, laboratory
Under 2 pCi/L: 25%2 to 4 pCi/L: 13%4 pCi/L and above: 62%

Of 89 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Carroll County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L2224.7%
2 to 4 pCi/L1213.5%
4 pCi/L and above5561.8%
What these figures count

These are the 89 tests reported to CDC for Carroll County over 2008 to 2017 (laboratory totals), 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: 2008 to 2017, laboratory. Measured data period: 2005 to 2017 (every CDC figure on file).

How to read these figures

Carroll County, Compared

Carroll County radon figures, compared

Calculated by Radon411

More than half: 61.8% of the 89 radon tests reported to CDC for Carroll County over the 2008 to 2017 laboratory totals read at least 4 pCi/L. That places it 3rd of 84 Virginia counties with 30 or more tests for the same period. That is 31.4 points above the 30.4% pooled from 131 Virginia counties.

The median result, 5.0 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 112.3 pCi/L. The rest split 24.7% under 2 pCi/L and 13.5% from 2 to 4 (Virginia: 44.7% and 24.9%). The reported tests do not follow EPA's Zone 2 label for Carroll County (predicted average between 2 and 4 pCi/L): 61.8% of them reached 4 pCi/L, fewer than that label suggests.

1 of its 6 bordering counties with figures ran higher, led by Wythe County at 65.5%; Surry County, NC reported 33.3%. Statewide for the same period, Russell County reported the highest share (67.3%) and Norfolk city the lowest (2.7%).

CDC's ten-year totals for Carroll County went from 120 tests (2005 to 2014) to 89 (2008 to 2017), the share going from 54.2% to 61.8%.

Nationally, every county with a figure for the same period pools to 35.7%; Carroll County sits 26.1 points above it. CDC also counts 11 tests taken after mitigation in Carroll County for the same period: tests in homes where a fix was already in.

Carroll County against Virginia, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Carroll County
Carroll County8961.8%5.0 pCi/LThis county
Virginia, pooled131 counties, pooled53,19930.4%Not pooled−31.4 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−26.1 points
Russell Countyhighest in the state4967.3%6.7 pCi/L+5.5 points
Norfolk citylowest in the state732.7%0.5 pCi/L−59.1 points
Wythe County, VAborders it11965.5%6.0 pCi/L+3.7 points
Patrick County, VAborders it5354.7%5.3 pCi/L−7.1 points
Pulaski County, VAborders it26849.6%3.9 pCi/L−12.2 points
Grayson County, VAborders it4744.7%3.8 pCi/L−17.1 points
Floyd County, VAborders it5442.6%3.3 pCi/L−19.2 points
Galax city, VAborders it1838.9%3.3 pCi/L−22.9 points
Surry County, NCborders it85533.3%2.4 pCi/L−28.5 points
Where Carroll County's reported results fell, 2008 to 2017, laboratory, beside Virginia and the United States
ResultCarroll County testsCarroll County shareVirginia shareU.S. shareAgainst Virginia
Under 2 pCi/L2224.7%44.7%39.6%−20.0 points
2 to 4 pCi/L1213.5%24.9%24.7%−11.4 points
4 pCi/L and above5561.8%30.4%35.7%+31.4 points
Carroll County ranked among the 84 Virginia counties with 30 or more tests, by share at or above 4 pCi/L, 2008 to 2017, laboratory
CountyRankTestsAt or above 4 pCi/LMedian
Russell County1 of 844967.3%6.7 pCi/L
Wythe County2 of 8411965.5%6.0 pCi/L
Carroll County3 of 848961.8%5.0 pCi/L
Smyth County4 of 8412361.0%5.5 pCi/L
Washington County5 of 8438458.1%4.8 pCi/L
Giles County6 of 8417456.9%4.8 pCi/L
Patrick County7 of 845354.7%5.3 pCi/L
Staunton city8 of 8433852.7%4.2 pCi/L
Bristol city9 of 8411050.9%4.2 pCi/L
Rockbridge County10 of 8411450.9%4.0 pCi/L
Scott County11 of 847550.7%4.0 pCi/L
Carroll County ten-year laboratory totals, against Virginia's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestVirginia, pooledChange from the row before
2008 to 20178961.8%5.0 pCi/L112.3 pCi/L30.4%−9.5 points
2007 to 20168071.3%6.0 pCi/L112.3 pCi/L30.6%+17.1 points
2006 to 201513154.2%4.6 pCi/L112.3 pCi/L30.7%Level
2005 to 201412054.2%4.6 pCi/L112.3 pCi/L30.3%First on file

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

Carroll County, Geology

The ground under Carroll County

Predicted

Most of the ground under Carroll County is one class on USGS's geologic map: 96.1% of its land is moderate radon potential, with 3.9% high. 96.1% of it lies in the area the map calls Blue Ridge, to which USGS gives a radon index of 10, in the moderate band (9 to 11).

USGS's geologic areas under Carroll County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Blue RidgeGranite, pegmatite, monazite, schist, and gneiss.Moderate1096.1%
Valley and RidgeCambrian dolomite, limestone, shale, and sandstone, Silurian-Ordovician limestone, dolomite, shale, and sandstone, Mississippian-Devonian sandstone, shale, limestone, gypsum, and coal.High153.9%

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

Carroll County beside the ground around it

Virginia as a whole has more high-potential ground than Carroll County: 47.9% of its land, against 3.9% here. Of the 7 counties that border it, 3 have more high-potential ground, Wythe County the most at 99.8%.

Share of land by USGS radon potential: Carroll County, the 7 counties bordering it and Virginia
AreaEPA zoneLow potentialModerate potentialHigh potential
Carroll CountyZone 2None96.1%3.9%
Galax cityZone 2None100%None
Pulaski CountyZone 1None2.5%97.5%
Wythe CountyZone 1None0.2%99.8%
Floyd CountyZone 2None100%None
Patrick CountyZone 1None55.7%44.3%
Surry County, NCZone 2None100%None
Grayson CountyZone 2None97.5%2.5%
Virginia133 counties, pooled by land areaVaries20.6%30.0%47.9%

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

Local help

Carroll County, Local resources

Radon testing and mitigation in Carroll County

What Virginia's program says
Phone
(804) 864-8161
Email
Radon@vdh.virginia.gov
Licensing of radon professionals
The Code of Virginia requires that Radon testers and mitigators be currently certified by either the National Radon Proficiency Program (NRPP) or the National Radon Safety Board (NRSB).

What it means

Carroll County, Questions

Questions about radon in Carroll County

Are radon levels high in Carroll County?

Over the 2008 to 2017 laboratory totals, 61.8% of the radon tests reported to CDC for Carroll County, Virginia were at or above 4 pCi/L, and the median reported pre-mitigation result was 5.0 pCi/L. Of 84 Virginia counties with 30 or more tests for the same period, 2 reported a higher share; pooled, the state comes to 30.4%.

Which counties border Carroll County?

Carroll County borders 7 counties: Galax city, VA, Pulaski County, VA, Wythe County, VA, Floyd County, VA, Patrick County, VA, Surry County, NC and Grayson County, VA.

Products

Carroll County, Products

Testing a home in Carroll County

In Carroll County, 61.8% of 89 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 30.4% pooled across Virginia. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Carroll County; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Carroll County homes, compared

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Carroll County, Bordering counties

Counties bordering Carroll County

Calculated by Radon411

Carroll County, Cities and towns

Cities and towns in Carroll County

The Census Bureau estimates 29,299 residents in Carroll County for July 1, 2025, 153 more than in 2020 (+0.5%). That works out to 62 people per square mile of land. Hillsville, its one incorporated place, has 2,836 residents, 9.7% of the total. Reported testing is thin here: 89 tests over 2008 to 2017, or 3.0 for every 1,000 residents (2025 estimate), where Virginia as a whole comes to 6.0.

Hillsville is the one incorporated place here; CDC publishes no figure by town, so it reads Carroll County's.

Hillsville, Carroll County: residents on July 1, 2025
PlaceResidentsSince 2020Share of residents
Hillsville2,836−1.7%9.7%

One incorporated place, 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).

Carroll County, Homes

Homes in Carroll County

Carroll County is a place of houses on their own lots: 76% of its 16,645 homes are detached single-family houses, against 61% across Virginia. Half of its homes were built before 1981, close to Virginia's 1984: 24% date from before 1960 and 22% from 2000 or later. Owners live in 78% of the occupied homes (Virginia: 67%), so for most households a test and a fix are their own to order.

Homes in Carroll County, Virginia, 2019 to 2023
HomesCarroll CountyVirginia
Housing units16,6453,654,784
Detached houses76%61%
In buildings of 5 or more2%19%
Mobile homes21%4%
Built before 196024%19%
Built since 200022%25%
Middle year built19811984
Owner-occupied78%67%

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