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Radon Levels in Dallas County, Texas

EPA puts Dallas County in Zone 3, its lowest radon zone, and most reported tests there come back low, though 8.4% of 728 (2008 to 2017, laboratory totals) reached 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

    8.4%

    1.8 pts below TX

    Dallas
    8.4%
    Texas
    10.2%

    728 tests, 2008 to 2017

  • Median result

    0.9pCi/L

    Below action level

    Dallas
    0.9 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    728

    2nd of 22 by tests

    Dallas
    728
    Harris
    733

    Reported to CDC before any fix, 2008 to 2017

  • 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

  • Rank in Texas

    8 of 22

    Middle half

    Dallas
    8.4%
    Randall
    69.0%

    By share, of 22 with 30+ tests

Read a result for Dallas County

Starts at Dallas County's median, 0.9 pCi/L

0.9pCi/L

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

EPA’s reading of 0.9 pCi/L

Below 2 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 below 2 pCi/L, the level at which EPA says a fix should be considered. Dallas County's median reported result, 2008 to 2017.

Interpret this reading

The data

Dallas County, At a glance

Dallas County at a glance

Predicted: EPA radon zone

EPA Zone 3: lower predicted potential

is EPA's lowest class, and its forecast for Dallas 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: Moderate across 65% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

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

Reported results by concentration band, Dallas County, 2008 to 2017, laboratory
Under 2 pCi/L: 76%2 to 4 pCi/L: 15%4 pCi/L and above: 9%

Of 728 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Dallas County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L55576.2%
2 to 4 pCi/L11215.4%
4 pCi/L and above618.4%
What these figures count

These are the 728 tests reported to CDC for Dallas 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

Dallas County, Compared

Dallas County radon figures, compared

Calculated by Radon411

Dallas County reports fewer high tests than Texas overall. 8.4% of its 728 tests over the 2008 to 2017 laboratory totals were at or above 4 pCi/L. That is 1.8 points below the 10.2% pooled from 138 Texas counties.

Ordered from highest share down, it comes 8th of 22 Texas counties with 30 or more tests for the same period. Nationally, every county with a figure for the same period pools to 35.7%; Dallas County sits 27.3 points below it.

Next door, the shares run from 6.8% in Denton County to 13.0% in Tarrant County, with Collin County and Denton County below Dallas County. Zone 3 on EPA's map (predicted average under 2 pCi/L) and a 8.4% share point the same way here.

Half the tests came in under 0.9 pCi/L and half over it; the single highest reached 7879.3 pCi/L. The rest split 76.2% under 2 pCi/L and 15.4% from 2 to 4 (Texas: 80.3% and 9.6%).

CDC's ten-year totals for Dallas County went from 401 tests (2005 to 2014) to 728 (2008 to 2017), the share going from 11.0% to 8.4%.

Dallas County against Texas, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Dallas County
Dallas County7288.4%0.9 pCi/LThis county
Texas, pooled138 counties, pooled4,61510.2%Not pooled+1.8 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled+27.3 points
Randall Countyhighest in the state8769.0%6.1 pCi/L+60.6 points
Nueces Countylowest in the state430.0%0.6 pCi/L−8.4 points
Ellis County, TXborders it1266.7%13.5 pCi/L+58.3 points
Rockwall County, TXborders it1618.8%1.2 pCi/L+10.4 points
Tarrant County, TXborders it28413.0%0.9 pCi/L+4.6 points
Collin County, TXborders it2897.6%1.0 pCi/L−0.8 points
Denton County, TXborders it1926.8%0.9 pCi/L−1.6 points
Kaufman County, TXborders it60.0%0.5 pCi/L−8.4 points
Where Dallas County's reported results fell, 2008 to 2017, laboratory, beside Texas and the United States
ResultDallas County testsDallas County shareTexas shareU.S. shareAgainst Texas
Under 2 pCi/L55576.2%80.3%39.6%−4.1 points
2 to 4 pCi/L11215.4%9.6%24.7%+5.8 points
4 pCi/L and above618.4%10.2%35.7%−1.8 points
Dallas County ranked among the 22 Texas counties with 30 or more tests, by share at or above 4 pCi/L, 2008 to 2017, laboratory
CountyRankTestsAt or above 4 pCi/LMedian
McLennan County3 of 223023.3%1.1 pCi/L
Potter County4 of 227423.0%1.4 pCi/L
Bell County5 of 223016.7%1.3 pCi/L
Tarrant County6 of 2228413.0%0.9 pCi/L
Travis County7 of 224269.2%0.9 pCi/L
Dallas County8 of 227288.4%0.9 pCi/L
Collin County9 of 222897.6%1.0 pCi/L
Denton County10 of 221926.8%0.9 pCi/L
Bexar County11 of 222016.5%0.6 pCi/L
Brazoria County12 of 22326.3%0.3 pCi/L
Smith County13 of 22525.8%0.8 pCi/L
Dallas County ten-year laboratory totals, against Texas' pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestTexas, pooledChange from the row before
2008 to 20177288.4%0.9 pCi/L7879.3 pCi/L10.2%−0.3 points
2007 to 20166998.7%1.0 pCi/L47.5 pCi/L10.4%−3.3 points
2006 to 201551012.0%1.1 pCi/L47.5 pCi/L11.0%+1.0 points
2005 to 201440111.0%1.1 pCi/L29.3 pCi/L10.6%First on file

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

Dallas County, Geology

The ground under Dallas County

Predicted

USGS's geologic map splits Dallas County: 64.8% of its land is moderate radon potential and 35.2% low. The map puts 64.8% of Dallas County in the area it calls Cretaceous Gulfian series and 35.2% in East Texas Province. USGS gives the first a radon index of 10, in the moderate band (9 to 11), and the second 6, in the low band (5 to 8).

USGS's geologic areas under Dallas County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Cretaceous Gulfian seriesCretaceous sandstone, shale, limestone, siltstone.Moderate1064.8%
East Texas ProvinceCretaceous through Quaternary marine sandstone, shale, chalk, limestone, siltstone, clay, and lignite.Low635.2%

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

Dallas County beside the ground around it

Across Texas 0.5% of the land is rated high; none of Dallas County's is. Of the 6 counties that border it, none has as large a share of moderate-potential ground; Collin County comes nearest at 59.3%.

Share of land by USGS radon potential: Dallas County, the 6 counties bordering it and Texas
AreaEPA zoneLow potentialModerate potentialHigh potential
Dallas CountyZone 335.2%64.8%None
Ellis CountyZone 358.7%41.3%None
Rockwall CountyZone 3100%NoneNone
Kaufman CountyZone 3100%NoneNone
Tarrant CountyZone 357.5%42.5%None
Collin CountyZone 340.7%59.3%None
Denton CountyZone 349.0%51.0%None
Texas254 counties, pooled by land areaVaries72.4%26.8%0.5%

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

Local help

Dallas County, Local resources

Radon testing and mitigation in Dallas County

Listed radon businesses with an address in Dallas County:

Listed radon professionals by town: Dallas, Carrollton, Richardson

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

Dallas County, Questions

Questions about radon in Dallas County

Are radon levels high in Dallas County?

Over the 2008 to 2017 laboratory totals, 8.4% of the radon tests reported to CDC for Dallas County, Texas were at or above 4 pCi/L, and the median reported pre-mitigation result was 0.9 pCi/L. Of 22 Texas counties with 30 or more tests for the same period, 7 reported a higher share; pooled, the state comes to 10.2%.

Which counties border Dallas County?

Dallas County borders 6 counties: Ellis County, Rockwall County, Kaufman County, Tarrant County, Collin County and Denton County.

Products

Dallas County, Products

Testing a home in Dallas County

In Dallas County, 8.4% of 728 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 10.2% pooled across Texas. 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 Dallas County.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Dallas County homes, compared

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Dallas County, Bordering counties

Counties bordering Dallas County

Calculated by Radon411

Dallas County, Cities and towns

Cities and towns in Dallas County

The Census Bureau estimates 2,661,397 residents in Dallas County for July 1, 2025, 50,595 more than in 2020 (+1.9%). Packed into its land, that is 3,048 people per square mile. Dallas, the largest place on its list (1,329,491 residents in all), extends beyond Dallas County, so no share of the total is worked out for it. Testing is reported here more often than across the state: CDC's 728 reported tests for 2008 to 2017 come to 0.3 for every 1,000 residents (2025 estimate), against 0.1 for Texas.

From Dallas to Combine, CDC publishes no figure by town: each reads Dallas County's.

The 12 largest cities and towns in Dallas County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Dallasextends beyond Dallas County1,329,491+2.0%Counted whole
Irving257,076+0.1%9.7%
Garlandextends beyond Dallas County249,625+1.3%Counted whole
Grand Prairieextends beyond Dallas County209,434+6.8%Counted whole
Mesquiteextends beyond Dallas County150,693+0.7%Counted whole
Lewisvilleextends beyond Dallas County139,006+10.0%Counted whole
Carrolltonextends beyond Dallas County134,562+0.7%Counted whole
Richardsonextends beyond Dallas County118,542−0.7%Counted whole
Rowlettextends beyond Dallas County67,890+8.2%Counted whole
Wylieextends beyond Dallas County63,842+10.3%Counted whole
DeSoto56,681+1.2%2.1%
Grapevineextends beyond Dallas County50,714−0.1%Counted whole
  • Cedar Hill (part)
  • Coppell (part)
  • Lancaster
  • Duncanville
  • Farmers Branch
  • Sachse (part)
  • Balch Springs
  • University Park
  • Seagoville (part)
  • Glenn Heights (part)
  • Addison
  • Sunnyvale
  • Highland Park
  • Hutchins
  • Wilmer
  • Ovilla (part)
  • Ferris (part)
  • Cockrell Hill
  • Combine (part)

31 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 Dallas County is counted whole, so it has no share.

Dallas County, Homes

Homes in Dallas County

Dallas County has 1,053,471 homes, and many share a building: 37% are in buildings of five or more, 52% are detached houses, against 65% across Texas. The homes are older than Texas' as a whole: half were built before 1982 (1990 for Texas), and 18% date from before 1960. 51% of occupied homes are lived in by their owner (Texas: 63%); in the rest a tenant can run a test, but a fix is the landlord's to make.

Homes in Dallas County, Texas, 2019 to 2023
HomesDallas CountyTexas
Housing units1,053,47111,890,808
Detached houses52%65%
In buildings of 5 or more37%21%
Mobile homes2%7%
Built before 196018%13%
Built since 200025%37%
Middle year built19821990
Owner-occupied51%63%

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