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Radon Levels in Clark County, Arkansas

EPA puts Clark County in Zone 3, its lowest radon zone, and only 4 radon tests from it are on file with CDC (2008 to 2017, laboratory totals). Homes with elevated levels occur in all three zones, so only a test measures yours.

Data checked By Radon411Methodology

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  • Nearest county

    45.8%

    Garland County, 36 miles

    Garland
    45.8%
    Arkansas
    22.7%

    Share at 4+ pCi/L, 48 tests, 2007 to 2016

  • Ground above low

    0.2%

    21.1 pts below Arkansas

    Clark
    0.2%
    Arkansas
    21.3%

    Share of land USGS rates moderate or high potential

  • Tests reported

    6

    Too few for a share

    Clark
    6
    Needed
    30

    2005 to 2014, laboratory

  • 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

Read a result for Clark County

Starts at EPA's action level

4.0pCi/L

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

EPA’s reading of 4.0 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.

Interpret this readingWhat a fix costs

The data

Clark County, At a glance

Clark County at a glance

Predicted: EPA radon zone

EPA Zone 3: lower predicted potential

is EPA's lowest class, and its forecast for Clark 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 100% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

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

CDC holds 4 reported tests for Clark County over the 2008 to 2017 laboratory totals, with a median of 1.3 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Clark County beside the counties around it is how this page reads it.

What these figures count

Only 4 tests were reported to CDC for Clark County over 2008 to 2017 (laboratory totals), 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: 2008 to 2017, laboratory. Measured data period: 2005 to 2017 (every CDC figure on file).

How to read these figures

Clark County, Compared

Clark County radon figures, compared

Calculated by Radon411

CDC's largest figure for Clark County rests on 6 tests over the 2005 to 2014 laboratory totals, 0 of them at or above 4 pCi/L, so each test moves its share by 16.7 points and no rank or comparison is drawn from it. Results reached as high as 3.5 pCi/L, with a middle value of 1.3 pCi/L.

The nearest counties with a figure are Garland County (36 miles away) at 45.8%, Saline County (50 miles away) at 31.9% and Pulaski County (70 miles away) at 6.8%. Pooled across 60 Arkansas counties, 22.7% of reported tests reached that level; across every county in the country with a figure, 35.8%.

Statewide for the same period, Garland County reported the highest share (45.8%) and Pulaski County the lowest (6.8%). EPA's 1993 map puts Clark County in Zone 3, its lowest label: a predicted county average under 2 pCi/L. USGS geology rates 100% of the county's land low radon potential.

Arkansas, the United States and the counties around Clark County, 2007 to 2016, laboratory
AreaTestsAt or above 4 pCi/LMedian
Arkansas, pooled60 counties, pooled68722.7%Not pooled
United States, pooled2,666 counties, pooled1,939,02535.8%Not pooled
Garland Countyhighest in the state4845.8%2.9 pCi/L
Pulaski Countylowest in the state1036.8%0.9 pCi/L
Montgomery County, ARborders it10.0%0.6 pCi/L
Hot Spring County, ARborders it10.0%2.1 pCi/L
Dallas County, ARborders it10.0%1.2 pCi/L
The nearest Arkansas counties to Clark County with 30 or more tests, 2007 to 2016, laboratory
CountyDistanceTestsAt or above 4 pCi/LMedian
Garland County36 mi4845.8%2.9 pCi/L
Saline County50 mi4731.9%2.2 pCi/L
Pulaski County70 mi1036.8%0.9 pCi/L
Washington County145 mi5614.3%2.2 pCi/L
Benton County169 mi14531.0%1.8 pCi/L
Clark County ten-year laboratory totals, against Arkansas' pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestArkansas, pooledChange from the row before
2008 to 201740.0%1.3 pCi/L1.8 pCi/L23.2%Level
2007 to 201640.0%1.3 pCi/L1.8 pCi/L22.7%Level
2006 to 201540.0%1.3 pCi/L1.8 pCi/L22.5%Level
2005 to 201460.0%1.3 pCi/L3.5 pCi/L24.3%First on file

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

Clark County, Geology

The ground under Clark County

Predicted

Most of the ground under Clark County is one class on USGS's geologic map: 99.8% of its land is low radon potential, with 0.2% moderate. The map puts 73.0% of Clark County in the area it calls West Gulf Coastal Plain and 26.8% in Athens Plateau/Fourche Mountains. USGS gives the first a radon index of 7 and the second 8, both in the low band (5 to 8).

USGS's geologic areas under Clark County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
West Gulf Coastal PlainGlauconitic, phosphatic, and carbonaceous sediments.Low773.0%
Athens Plateau/Fourche MountainsMississippian and Pennsylvanian sandstones and shales.Low826.8%

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

Clark County beside the ground around it

Arkansas as a whole has more moderate-potential ground than Clark County: 21.3% of its land, against 0.2% here. Of the 6 counties that border it, 3 have more moderate-potential ground, Montgomery County the most at 72.4%.

Share of land by USGS radon potential: Clark County, the 6 counties bordering it and Arkansas
AreaEPA zoneLow potentialModerate potentialHigh potential
Clark CountyZone 399.8%0.2%None
Hot Spring CountyZone 375.1%24.9%None
Dallas CountyZone 3100%NoneNone
Pike CountyZone 392.0%8.0%None
Nevada CountyZone 3100%NoneNone
Ouachita CountyZone 3100%NoneNone
Montgomery CountyZone 227.6%72.4%None
Arkansas75 counties, pooled by land areaVaries78.7%21.3%None

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

Local help

Clark County, Local resources

Radon testing and mitigation in Clark County

What Arkansas's program says
Phone
501-661-2621
Email
ADH.EPI.Radon@arkansas.gov

What it means

Clark County, Questions

Questions about radon in Clark County

Are radon levels high in Clark County?

Over the 2008 to 2017 laboratory totals, 0.0% of the radon tests reported to CDC for Clark County, Arkansas were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.3 pCi/L. Of the 5 nearest counties with a figure, within 169 miles, the share of tests at or above 4 pCi/L runs from 6.8% to 45.8%.

Which counties border Clark County?

Clark County borders 6 counties: Hot Spring County, Dallas County, Pike County, Nevada County, Ouachita County and Montgomery County.

Products

Clark County, Products

Testing a home in Clark County

No CDC figure names Clark County; the nearest county with one, Garland County (36 miles away), reported 45.8% of its tests at or above 4 pCi/L over the 2007 to 2016 laboratory totals, the only reading nearby until a test of this home. 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 Clark County.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Clark County homes, compared

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Clark County, Bordering counties

Counties bordering Clark County

Calculated by Radon411

Clark County, Cities and towns

Cities and towns in Clark County

About 20,938 people live in Clark County by the Census Bureau's estimate for July 1, 2025, 466 fewer than in 2020 (−2.2%). That works out to 24 people per square mile of land. Its largest town, Arkadelphia, has 9,916 residents, 47.4% of the total. Together its 7 incorporated places hold 63.2% of those residents; the other 36.8% live outside any of them. CDC's 6 reported tests for 2005 to 2014 work out to 0.3 per 1,000 residents (2025 estimate), close to Arkansas' 0.2.

From Arkadelphia to Whelen Springs, CDC publishes no figure by town: each reads Clark County's.

The cities and towns in Clark County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Arkadelphia9,916−4.3%47.4%
Gurdon1,817−1.3%8.7%
Amity674−0.1%3.2%
Caddo Valley588−0.3%2.8%
Okolona98+1.0%0.5%
Gum Springs91Level0.4%
Whelen Springs47+2.2%0.2%

7 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).

Clark County, Homes

Homes in Clark County

Of Clark County's 10,012 homes, 64% are detached houses, against 70% across Arkansas; 14% are mobile homes. Half of its homes were built before 1986, close to Arkansas' 1987: 16% date from before 1960 and 25% from 2000 or later. 62% of occupied homes are lived in by their owner (Arkansas: 66%); in the rest a tenant can run a test, but a fix is the landlord's to make.

Homes in Clark County, Arkansas, 2019 to 2023
HomesClark CountyArkansas
Housing units10,0121,382,664
Detached houses64%70%
In buildings of 5 or more14%10%
Mobile homes14%11%
Built before 196016%14%
Built since 200025%28%
Middle year built19861987
Owner-occupied62%66%

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