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Radon Levels in Denton County, Texas

EPA puts Denton County in Zone 3, its lowest radon zone, and most reported tests there come back low, though 6.8% of 192 (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

How to test this homeFind a certified tester

  • Share at 4+ pCi/L

    6.8%

    3.4 pts below TX

    Denton
    6.8%
    Texas
    10.2%

    192 tests, 2008 to 2017

  • Median result

    0.9pCi/L

    Below action level

    Denton
    0.9 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    192

    7th of 22 by tests

    Denton
    192
    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

    10 of 22

    Middle half

    Denton
    6.8%
    Randall
    69.0%

    By share, of 22 with 30+ tests

Read a result for Denton County

Starts at Denton 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. Denton County's median reported result, 2008 to 2017.

Interpret this reading

The data

Denton County, At a glance

Denton County at a glance

Predicted: EPA radon zone

EPA Zone 3: lower predicted potential

is EPA's lowest class, and its forecast for Denton 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 51% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

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

Reported results by concentration band, Denton County, 2008 to 2017, laboratory
Under 2 pCi/L: 82%2 to 4 pCi/L: 11%4 pCi/L and above: 7%

Of 192 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Denton County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L15781.8%
2 to 4 pCi/L2211.5%
4 pCi/L and above136.8%
What these figures count

These are the 192 tests reported to CDC for Denton 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

Denton County, Compared

Denton County radon figures, compared

Calculated by Radon411

Denton County reports fewer high tests than Texas overall. 6.8% of its 192 tests over the 2008 to 2017 laboratory totals were at or above 4 pCi/L. That is 3.4 points below the 10.2% pooled from 138 Texas counties.

Ordered from highest share down, it comes 10th 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%; Denton County sits 28.9 points below it.

Next door, the shares run from 7.6% in Collin County to 13.0% in Tarrant County. Zone 3 on EPA's map (predicted average under 2 pCi/L) and a 6.8% share point the same way here.

Half the tests came in under 0.9 pCi/L and half over it; the single highest reached 98.8 pCi/L. The rest split 81.8% under 2 pCi/L and 11.5% from 2 to 4 (Texas: 80.3% and 9.6%).

CDC's ten-year totals for Denton County went from 135 tests (2005 to 2014) to 192 (2008 to 2017), the share going from 10.4% to 6.8%.

Denton County against Texas, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Denton County
Denton County1926.8%0.9 pCi/LThis county
Texas, pooled138 counties, pooled4,61510.2%Not pooled+3.4 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled+28.9 points
Randall Countyhighest in the state8769.0%6.1 pCi/L+62.2 points
Nueces Countylowest in the state430.0%0.6 pCi/L−6.8 points
Tarrant County, TXborders it28413.0%0.9 pCi/L+6.2 points
Dallas County, TXborders it7288.4%0.9 pCi/L+1.6 points
Collin County, TXborders it2897.6%1.0 pCi/L+0.8 points
Grayson County, TXborders it205.0%1.1 pCi/L−1.8 points
Wise County, TXborders it40.0%0.9 pCi/L−6.8 points
Cooke County, TXborders it10.0%1.6 pCi/L−6.8 points
Where Denton County's reported results fell, 2008 to 2017, laboratory, beside Texas and the United States
ResultDenton County testsDenton County shareTexas shareU.S. shareAgainst Texas
Under 2 pCi/L15781.8%80.3%39.6%+1.5 points
2 to 4 pCi/L2211.5%9.6%24.7%+1.9 points
4 pCi/L and above136.8%10.2%35.7%−3.4 points
Denton 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
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
Montgomery County14 of 221883.2%0.8 pCi/L
Harris County15 of 227332.9%0.4 pCi/L
Denton County ten-year laboratory totals, against Texas' pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestTexas, pooledChange from the row before
2008 to 20171926.8%0.9 pCi/L98.8 pCi/L10.2%−0.4 points
2007 to 20161817.2%0.9 pCi/L98.8 pCi/L10.4%−2.3 points
2006 to 20151489.5%0.9 pCi/L98.8 pCi/L11.0%−0.9 points
2005 to 201413510.4%0.9 pCi/L98.8 pCi/L10.6%First on file

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

Denton County, Geology

The ground under Denton County

Predicted

USGS's geologic map splits Denton County: 51.0% of its land is moderate radon potential and 49.0% low. The map puts 51.0% of Denton County in the area it calls Cretaceous Gulfian series and 49.0% in Central Texas/Gulf Coast Plain. USGS gives the first a radon index of 10, in the moderate band (9 to 11), and the second 7, in the low band (5 to 8).

USGS's geologic areas under Denton County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Cretaceous Gulfian seriesCretaceous sandstone, shale, limestone, siltstone.Moderate1051.0%
Central Texas/Gulf Coast PlainCretaceous through Quaternary marine sandstone, shale, chalk, limestone, siltstone, clay, and lignite.Low749.0%

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

Denton County beside the ground around it

Across Texas 0.5% of the land is rated high; none of Denton County's is. Of the 6 counties that border it, 3 have more moderate-potential ground, Grayson County the most at 85.4%.

Share of land by USGS radon potential: Denton County, the 6 counties bordering it and Texas
AreaEPA zoneLow potentialModerate potentialHigh potential
Denton CountyZone 349.0%51.0%None
Cooke CountyZone 375.6%24.4%None
Wise CountyZone 3100%NoneNone
Grayson CountyZone 314.6%85.4%None
Collin CountyZone 340.7%59.3%None
Tarrant CountyZone 357.5%42.5%None
Dallas CountyZone 335.2%64.8%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

Denton County, Local resources

Radon testing and mitigation in Denton County

Listed radon professionals by town: Dallas, Carrollton

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

Denton County, Questions

Questions about radon in Denton County

Are radon levels high in Denton County?

Over the 2008 to 2017 laboratory totals, 6.8% of the radon tests reported to CDC for Denton 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, 9 reported a higher share; pooled, the state comes to 10.2%.

Which counties border Denton County?

Denton County borders 6 counties: Cooke County, Wise County, Grayson County, Collin County, Tarrant County and Dallas County.

Products

Denton County, Products

Testing a home in Denton County

In Denton County, 6.8% of 192 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 Denton County.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Denton County homes, compared

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Denton County, Bordering counties

Counties bordering Denton County

Calculated by Radon411

Denton County, Cities and towns

Cities and towns in Denton County

Denton County is growing: the Census Bureau puts it at 1,069,346 residents on July 1, 2025, up 16.9% from 914,517 in 2020. Packed into its land, that is 1,217 people per square mile. Dallas, the largest place on its list (1,329,491 residents in all), extends beyond Denton County, so no share of the total is worked out for it. CDC's 192 reported tests for 2008 to 2017 work out to 0.2 per 1,000 residents (2025 estimate), close to Texas' 0.1.

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

The 12 largest cities and towns in Denton County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Dallasextends beyond Denton County1,329,491+2.0%Counted whole
Fort Worthextends beyond Denton County1,028,117+11.3%Counted whole
Planoextends beyond Denton County293,028+2.3%Counted whole
Friscoextends beyond Denton County236,955+16.9%Counted whole
Denton169,431+20.0%15.8%
Lewisvilleextends beyond Denton County139,006+10.0%Counted whole
Carrolltonextends beyond Denton County134,562+0.7%Counted whole
Flower Moundextends beyond Denton County79,540+4.0%Counted whole
Celinaextends beyond Denton County64,427+257.3%Counted whole
Little Elm62,727+34.1%5.9%
Grapevineextends beyond Denton County50,714−0.1%Counted whole
The Colony46,196+3.2%4.3%
  • Prosper (part)
  • Coppell (part)
  • Southlake (part)
  • Corinth
  • Highland Village
  • Trophy Club (part)
  • Providence Village
  • Northlake
  • Roanoke (part)
  • Sanger (part)
  • Aubrey
  • Pilot Point (part)
  • Lake Dallas
  • Justin
  • Oak Point
  • Hickory Creek
  • Krum
  • Argyle
  • Haslet (part)
  • Double Oak
  • Shady Shores
  • Hackberry
  • Ponder
  • Copper Canyon
The other 9 places in Denton County
  • Westlake (part)
  • Krugerville
  • Cross Roads
  • Bartonville
  • New Fairview (part)
  • Lakewood Village
  • DISH
  • Hebron (part)
  • Draper

45 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 Denton County is counted whole, so it has no share.

Denton County, Homes

Homes in Denton County

Of Denton County's 364,120 homes, 68% are detached houses, against 65% across Texas; 22% are in buildings of five or more homes. Much of Denton County is recent building: 55% of its homes have gone up since 2000 and the middle year built is 2002, against 1990 for Texas. 65% 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 Denton County, Texas, 2019 to 2023
HomesDenton CountyTexas
Housing units364,12011,890,808
Detached houses68%65%
In buildings of 5 or more22%21%
Mobile homes3%7%
Built before 19603%13%
Built since 200055%37%
Middle year built20021990
Owner-occupied65%63%

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