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Radon Levels in Travis County, Texas

EPA puts Travis County in Zone 3, its lowest radon zone, and most reported tests there come back low, though 9.2% of 426 (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

    9.2%

    1.0 pts below TX

    Travis
    9.2%
    Texas
    10.2%

    426 tests, 2008 to 2017

  • Median result

    0.9pCi/L

    Below action level

    Travis
    0.9 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    426

    3rd of 22 by tests

    Travis
    426
    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

    7 of 22

    Middle half

    Travis
    9.2%
    Randall
    69.0%

    By share, of 22 with 30+ tests

Read a result for Travis County

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

Interpret this reading

The data

Travis County, At a glance

Travis County at a glance

Predicted: EPA radon zone

EPA Zone 3: lower predicted potential

is EPA's lowest class, and its forecast for Travis 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 86% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

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

Reported results by concentration band, Travis County, 2008 to 2017, laboratory
Under 2 pCi/L: 77%2 to 4 pCi/L: 14%4 pCi/L and above: 9%

Of 426 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Travis County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L32676.5%
2 to 4 pCi/L6114.3%
4 pCi/L and above399.2%
What these figures count

These are the 426 tests reported to CDC for Travis 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

Travis County, Compared

Travis County radon figures, compared

Calculated by Radon411

Travis County reports fewer high tests than Texas overall. 9.2% of its 426 tests over the 2008 to 2017 laboratory totals were at or above 4 pCi/L. That is 1.0 points below the 10.2% pooled from 138 Texas counties.

Ordered from highest share down, it comes 7th 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%; Travis County sits 26.5 points below it.

Williamson County, the one bordering county with a figure for the same period, reported 1.9%. Zone 3 on EPA's map (predicted average under 2 pCi/L) and a 9.2% share point the same way here.

Half the tests came in under 0.9 pCi/L and half over it; the single highest reached 389.9 pCi/L. The rest split 76.5% under 2 pCi/L and 14.3% from 2 to 4 (Texas: 80.3% and 9.6%).

CDC's ten-year totals for Travis County went from 354 tests (2005 to 2014) to 426 (2008 to 2017), the share going from 10.2% to 9.2%.

Travis County against Texas, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Travis County
Travis County4269.2%0.9 pCi/LThis county
Texas, pooled138 counties, pooled4,61510.2%Not pooled+1.0 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled+26.5 points
Randall Countyhighest in the state8769.0%6.1 pCi/L+59.8 points
Nueces Countylowest in the state430.0%0.6 pCi/L−9.2 points
Burnet County, TXborders it771.4%27.4 pCi/L+62.2 points
Bastrop County, TXborders it1361.5%6.5 pCi/L+52.3 points
Hays County, TXborders it2317.4%0.5 pCi/L+8.2 points
Williamson County, TXborders it1031.9%0.7 pCi/L−7.3 points
Blanco County, TXborders it20.0%0.2 pCi/L−9.2 points
Caldwell County, TXborders it20.0%1.1 pCi/L−9.2 points
Where Travis County's reported results fell, 2008 to 2017, laboratory, beside Texas and the United States
ResultTravis County testsTravis County shareTexas shareU.S. shareAgainst Texas
Under 2 pCi/L32676.5%80.3%39.6%−3.8 points
2 to 4 pCi/L6114.3%9.6%24.7%+4.7 points
4 pCi/L and above399.2%10.2%35.7%−1.0 points
Travis 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
Lubbock County2 of 2212255.7%4.8 pCi/L
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
Travis County ten-year laboratory totals, against Texas' pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestTexas, pooledChange from the row before
2008 to 20174269.2%0.9 pCi/L389.9 pCi/L10.2%−0.1 points
2007 to 20164089.3%0.8 pCi/L389.9 pCi/L10.4%−0.5 points
2006 to 20153769.8%0.8 pCi/L389.9 pCi/L11.0%−0.4 points
2005 to 201435410.2%0.9 pCi/L389.9 pCi/L10.6%First on file

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

Travis County, Geology

The ground under Travis County

Predicted

Most of the ground under Travis County is one class on USGS's geologic map: 86.5% of its land is low radon potential, with 13.5% moderate. The map puts 42.4% of Travis County in the area it calls East Texas Province and 24.6% in Southern High Plains and Plateaus, with 2 smaller areas beside them. USGS gives the first a radon index of 6 and the second 7, both in the low band (5 to 8).

USGS's geologic areas under Travis County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
East Texas ProvinceCretaceous through Quaternary marine sandstone, shale, chalk, limestone, siltstone, clay, and lignite.Low642.4%
Southern High Plains and PlateausPaleozoic and Mesozoic sandstone, limestone, shale.Low724.6%
Central Texas/Gulf Coast PlainCretaceous through Quaternary marine sandstone, shale, chalk, limestone, siltstone, clay, and lignite.Low719.6%
Cretaceous Gulfian seriesCretaceous sandstone, shale, limestone, siltstone.Moderate1013.5%

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

Travis County beside the ground around it

Across Texas 0.5% of the land is rated high; none of Travis County's is. Of the 6 counties that border it, 3 have more moderate-potential ground, Blanco County the most at 35.3%.

Share of land by USGS radon potential: Travis County, the 6 counties bordering it and Texas
AreaEPA zoneLow potentialModerate potentialHigh potential
Travis CountyZone 386.5%13.5%None
Hays CountyZone 394.6%5.4%None
Williamson CountyZone 384.6%15.4%None
Bastrop CountyZone 3100%NoneNone
Caldwell CountyZone 3100%NoneNone
Blanco CountyZone 364.7%35.3%None
Burnet CountyZone 371.3%28.7%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

Travis County, Local resources

Radon testing and mitigation in Travis 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

Travis County, Questions

Questions about radon in Travis County

Are radon levels high in Travis County?

Over the 2008 to 2017 laboratory totals, 9.2% of the radon tests reported to CDC for Travis 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, 6 reported a higher share; pooled, the state comes to 10.2%.

Which counties border Travis County?

Travis County borders 6 counties: Hays County, Williamson County, Bastrop County, Caldwell County, Blanco County and Burnet County.

Products

Travis County, Products

Testing a home in Travis County

In Travis County, 9.2% of 426 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 Travis County.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Travis County homes, compared

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Travis County, Bordering counties

Counties bordering Travis County

Calculated by Radon411

Travis County, Cities and towns

Cities and towns in Travis County

Travis County is growing: the Census Bureau puts it at 1,389,670 residents on July 1, 2025, up 7.2% from 1,296,572 in 2020. Packed into its land, that is 1,398 people per square mile. Austin, the largest place on its list (1,002,632 residents in all), extends beyond Travis County, so no share of the total is worked out for it. Testing is reported here more often than across the state: CDC's 426 reported tests for 2008 to 2017 come to 0.3 for every 1,000 residents (2025 estimate), against 0.1 for Texas.

From Austin to Creedmoor, CDC publishes no figure by town: each reads Travis County's.

The 12 largest cities and towns in Travis County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Austinextends beyond Travis County1,002,632+4.2%Counted whole
Round Rockextends beyond Travis County141,282+17.2%Counted whole
Leanderextends beyond Travis County91,132+49.7%Counted whole
Cedar Parkextends beyond Travis County79,032+1.3%Counted whole
Pflugervilleextends beyond Travis County68,316+4.3%Counted whole
Manor23,070+63.4%1.7%
Lakeway19,027−1.2%1.4%
Elginextends beyond Travis County13,327+35.9%Counted whole
Lago Vista10,498+16.9%0.8%
Bee Cave8,464−7.6%0.6%
West Lake Hills3,229−6.6%0.2%
Jonestown2,687+11.6%0.2%
  • Briarcliff
  • The Hills
  • Rollingwood
  • Point Venture
  • Mustang Ridge (part)
  • Sunset Valley
  • San Leanna
  • Volente
  • Webberville
  • Creedmoor (part)

22 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 Travis County is counted whole, so it has no share.

Travis County, Homes

Homes in Travis County

Travis County has 594,638 homes, and many share a building: 34% are in buildings of five or more, 52% are detached houses, against 65% across Texas. Half of its homes were built before 1997, close to Texas' 1990: 7% date from before 1960 and 45% from 2000 or later. 53% 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 Travis County, Texas, 2019 to 2023
HomesTravis CountyTexas
Housing units594,63811,890,808
Detached houses52%65%
In buildings of 5 or more34%21%
Mobile homes3%7%
Built before 19607%13%
Built since 200045%37%
Middle year built19971990
Owner-occupied53%63%

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