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Radon Levels in Ellis County, Texas

EPA puts Ellis County in Zone 3, its lowest radon zone, and only 12 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

How to test this homeFind a certified tester

  • Highest bordering

    10.6%

    Tarrant County

    Tarrant
    10.6%
    Dallas
    8.7%

    2 of 7 neighbours have 30+ tests, 2007 to 2016

  • Nearest county

    8.7%

    Dallas County, 29 miles

    Dallas
    8.7%
    Texas
    10.4%

    Share at 4+ pCi/L, 699 tests, 2007 to 2016

  • Ground above low

    41.3%

    14.0 pts above Texas

    Ellis
    41.3%
    Texas
    27.3%

    Share of land USGS rates moderate or high potential

  • Tests reported

    14

    Too few for a share

    Ellis
    14
    Needed
    30

    2007 to 2016, 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 Ellis 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

Ellis County, At a glance

Ellis County at a glance

Predicted: EPA radon zone

EPA Zone 3: lower predicted potential

is EPA's lowest class, and its forecast for Ellis 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 59% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

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

CDC holds 12 reported tests for Ellis County over the 2008 to 2017 laboratory totals, with a median of 13.5 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Ellis County beside the counties around it is how this page reads it.

What these figures count

Only 12 tests were reported to CDC for Ellis 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

Ellis County, Compared

Ellis County radon figures, compared

Calculated by Radon411

CDC's largest figure for Ellis County rests on 14 tests over the 2007 to 2016 laboratory totals, 8 of them at or above 4 pCi/L, so each test moves its share by 7.1 points and no rank or comparison is drawn from it. Results reached as high as 30.2 pCi/L, with a middle value of 11.0 pCi/L.

Of the counties bordering it, 2 have a figure over the 2007 to 2016 laboratory totals: Tarrant County reported the largest share at or above 4 pCi/L, 10.6%, and Dallas County the smallest, 8.7%. Farther out, Collin County (59 miles away) at 7.7%, McLennan County (60 miles away) at 17.1% and Denton County (62 miles away) at 7.2% have figures too. Pooled across 140 Texas counties, 10.4% of reported tests reached that level; across every county in the country with a figure, 35.8%.

Statewide for the same period, Randall County reported the highest share (71.4%) and Nueces County the lowest (0.0%). EPA's 1993 map puts Ellis County in Zone 3, its lowest label: a predicted county average under 2 pCi/L. USGS geology rates 59% of the county's land low radon potential.

Texas, the United States and the counties around Ellis County, 2007 to 2016, laboratory
AreaTestsAt or above 4 pCi/LMedian
Texas, pooled140 counties, pooled4,54810.4%Not pooled
United States, pooled2,666 counties, pooled1,939,02535.8%Not pooled
Randall Countyhighest in the state8471.4%6.2 pCi/L
Nueces Countylowest in the state450.0%0.6 pCi/L
Tarrant County, TXborders it31210.6%0.9 pCi/L
Dallas County, TXborders it6998.7%1.0 pCi/L
Hill County, TXborders it50.0%0.1 pCi/L
Kaufman County, TXborders it40.0%0.3 pCi/L
Navarro County, TXborders it60.0%0.8 pCi/L
Henderson County, TXborders it10.0%0.8 pCi/L
Johnson County, TXborders it140.0%0.8 pCi/L
The nearest Texas counties to Ellis County with 30 or more tests, 2007 to 2016, laboratory
CountyDistanceTestsAt or above 4 pCi/LMedian
Dallas County29 mi6998.7%1.0 pCi/L
Tarrant County41 mi31210.6%0.9 pCi/L
Collin County59 mi2847.7%1.0 pCi/L
McLennan County60 mi4117.1%1.0 pCi/L
Denton County62 mi1817.2%0.9 pCi/L
Smith County89 mi339.1%0.8 pCi/L
Bell County99 mi3514.3%1.1 pCi/L
Brazos County120 mi490.0%0.2 pCi/L
Ellis County ten-year laboratory totals, against Texas' pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestTexas, pooledChange from the row before
2008 to 20171266.7%13.5 pCi/L30.2 pCi/L10.2%+9.6 points
2007 to 20161457.1%11.0 pCi/L30.2 pCi/L10.4%+57.1 points
2006 to 201560.0%0.9 pCi/L1.3 pCi/L11.0%Level
2005 to 201480.0%0.9 pCi/L1.3 pCi/L10.6%First on file

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

Ellis County, Geology

The ground under Ellis County

Predicted

USGS's geologic map splits Ellis County: 58.7% of its land is low radon potential and 41.3% moderate. The map puts 58.7% of Ellis County in the area it calls East Texas Province and 41.3% in Cretaceous Gulfian series. USGS gives the first a radon index of 6, in the low band (5 to 8), and the second 10, in the moderate band (9 to 11).

USGS's geologic areas under Ellis County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
East Texas ProvinceCretaceous through Quaternary marine sandstone, shale, chalk, limestone, siltstone, clay, and lignite.Low658.7%
Cretaceous Gulfian seriesCretaceous sandstone, shale, limestone, siltstone.Moderate1041.3%

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

Ellis County beside the ground around it

Across Texas 0.5% of the land is rated high; none of Ellis County's is. Of the 7 counties that border it, 4 have more moderate-potential ground, Dallas County the most at 64.8%.

Share of land by USGS radon potential: Ellis County, the 7 counties bordering it and Texas
AreaEPA zoneLow potentialModerate potentialHigh potential
Ellis CountyZone 358.7%41.3%None
Navarro CountyZone 3100%NoneNone
Dallas CountyZone 335.2%64.8%None
Hill CountyZone 345.1%54.9%None
Johnson CountyZone 346.0%54.0%None
Kaufman CountyZone 3100%NoneNone
Tarrant CountyZone 357.5%42.5%None
Henderson CountyZone 3100%NoneNone
Texas254 counties, pooled by land areaVaries72.4%26.8%0.5%

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

Local help

Ellis County, Local resources

Radon testing and mitigation in Ellis County

What Texas's program says
Licensing of radon professionals
There are no radon certification requirements for the State of Texas at this time, but the National Radon Proficiency Program lists radon testers and mitigators within Texas that have passed a rigorous national certification program.

What it means

Ellis County, Questions

Questions about radon in Ellis County

Are radon levels high in Ellis County?

Over the 2008 to 2017 laboratory totals, 66.7% of the radon tests reported to CDC for Ellis County, Texas were at or above 4 pCi/L, and the median reported pre-mitigation result was 13.5 pCi/L. Of the counties bordering it, 2 have a figure over the 2007 to 2016 laboratory totals: Tarrant County reported the largest share at or above 4 pCi/L, 10.6%, and Dallas County the smallest, 8.7%.

Which counties border Ellis County?

Ellis County borders 7 counties: Navarro County, Dallas County, Hill County, Johnson County, Kaufman County, Tarrant County and Henderson County.

Products

Ellis County, Products

Testing a home in Ellis County

No CDC figure names Ellis County; the nearest county with one, Dallas County (29 miles away), reported 8.7% 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 Ellis County.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Ellis County homes, compared

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Ellis County, Bordering counties

Counties bordering Ellis County

Calculated by Radon411

Ellis County, Cities and towns

Cities and towns in Ellis County

Ellis County is growing: the Census Bureau puts it at 240,867 residents on July 1, 2025, up 24.0% from 194,322 in 2020. That works out to 257 people per square mile of land. Grand Prairie, the largest place on its list (209,434 residents in all), extends beyond Ellis County, so no share of the total is worked out for it. Reported testing is thin here: 14 tests over 2007 to 2016, or 0.1 for every 1,000 residents (2025 estimate), where Texas as a whole comes to 0.1.

From Grand Prairie to Alma, CDC publishes no figure by town: each reads Ellis County's.

The 12 largest cities and towns in Ellis County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Grand Prairieextends beyond Ellis County209,434+6.8%Counted whole
Mansfieldextends beyond Ellis County84,444+16.0%Counted whole
Waxahachie50,090+20.4%20.8%
Cedar Hillextends beyond Ellis County49,801+1.4%Counted whole
Midlothian46,683+31.6%19.4%
Ennis25,694+27.1%10.7%
Red Oak20,394+41.2%8.5%
Glenn Heightsextends beyond Ellis County20,327+26.3%Counted whole
Venusextends beyond Ellis County8,870+93.3%Counted whole
Ovillaextends beyond Ellis County4,808+12.8%Counted whole
Ferrisextends beyond Ellis County4,291+52.6%Counted whole
Palmer2,644+9.3%1.1%
  • Italy
  • Oak Leaf
  • Maypearl
  • Garrett
  • Milford
  • Pecan Hill
  • Bardwell
  • Alma

20 incorporated places, as listed in the U.S. Census Bureau’s 2020 place reference files. “(part)” marks a place that extends into another county. Residents: U.S. Census Bureau population estimates for July 1, 2025 (Vintage 2025). A place that extends beyond Ellis County is counted whole, so it has no share.

Ellis County, Homes

Homes in Ellis County

Ellis County is a place of houses on their own lots: 79% of its 72,541 homes are detached single-family houses, against 65% across Texas. Much of Ellis County is recent building: 50% of its homes have gone up since 2000 and the middle year built is 2000, against 1990 for Texas. Owners live in 76% of the occupied homes (Texas: 63%), so for most households a test and a fix are their own to order.

Homes in Ellis County, Texas, 2019 to 2023
HomesEllis CountyTexas
Housing units72,54111,890,808
Detached houses79%65%
In buildings of 5 or more9%21%
Mobile homes8%7%
Built before 19609%13%
Built since 200050%37%
Middle year built20001990
Owner-occupied76%63%

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