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Radon Levels in Austin County, Texas

EPA puts Austin County in Zone 3, its lowest radon zone, and only 2 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

  • Highest bordering

    3.4%

    Fort Bend County

    Fort Bend
    3.4%

    1 of 6 neighbours have 30+ tests, 2007 to 2016

  • Nearest county

    3.4%

    Fort Bend County, 39 miles

    Fort Bend
    3.4%
    Texas
    10.4%

    Share at 4+ pCi/L, 117 tests, 2007 to 2016

  • Ground above low

    None

    27.3 pts below Texas

    Austin
    0.0%
    Texas
    27.3%

    Share of land USGS rates moderate or high potential

  • Tests reported

    3

    Too few for a share

    Austin
    3
    Needed
    30

    2006 to 2015, 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 Austin 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.

The data

Austin County, At a glance

Austin County at a glance

Predicted: EPA radon zone

EPA Zone 3: lower predicted potential

is EPA's lowest class, and its forecast for Austin 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 Austin County, 2008 to 2017, laboratory

CDC holds 2 reported tests for Austin County over the 2008 to 2017 laboratory totals, with a median of 0.1 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Austin County beside the counties around it is how this page reads it.

What these figures count

Only 2 tests were reported to CDC for Austin 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

Austin County, Compared

Austin County radon figures, compared

Calculated by Radon411

CDC's largest figure for Austin County rests on 3 tests over the 2006 to 2015 laboratory totals, 0 of them at or above 4 pCi/L, so each test moves its share by 33.3 points and no rank or comparison is drawn from it. Results reached as high as 0.5 pCi/L, with a middle value of 0.1 pCi/L.

Fort Bend County, the one bordering county with a figure over the 2007 to 2016 laboratory totals, reported 3.4% of its tests at or above 4 pCi/L. Farther out, Harris County (53 miles away) at 3.1%, Brazos County (53 miles away) at 0.0% and Montgomery County (54 miles away) at 7.1% 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 Austin 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.

Texas, the United States and the counties around Austin 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
Fort Bend County, TXborders it1173.4%0.2 pCi/L
Fayette County, TXborders it60.0%0.1 pCi/L
Wharton County, TXborders it90.0%0.5 pCi/L
Waller County, TXborders it70.0%0.1 pCi/L
Colorado County, TXborders it10.0%1.5 pCi/L
The nearest Texas counties to Austin County with 30 or more tests, 2007 to 2016, laboratory
CountyDistanceTestsAt or above 4 pCi/LMedian
Fort Bend County39 mi1173.4%0.2 pCi/L
Harris County53 mi7753.1%0.2 pCi/L
Brazos County53 mi490.0%0.2 pCi/L
Montgomery County54 mi857.1%0.6 pCi/L
Brazoria County69 mi326.3%0.3 pCi/L
Galveston County86 mi830.0%0.2 pCi/L
Williamson County95 mi982.0%0.7 pCi/L
Travis County95 mi4089.3%0.8 pCi/L
Austin County ten-year laboratory totals, against Texas' pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestTexas, pooledChange from the row before
2008 to 201720.0%0.1 pCi/L0.1 pCi/L10.2%Level
2007 to 201620.0%0.1 pCi/L0.1 pCi/L10.4%Level
2006 to 201530.0%0.1 pCi/L0.5 pCi/L11.0%Level
2005 to 201430.0%0.1 pCi/L0.5 pCi/L10.6%First on file

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

Austin County, Geology

The ground under Austin County

Predicted

USGS's geologic map puts all of Austin County's mapped land in one class: low radon potential. All of it lies in the area the map calls Coastal Plain, to which USGS gives a radon index of 7, in the low band (5 to 8).

USGS's geologic areas under Austin County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Coastal PlainCretaceous through Quaternary marine sandstone, shale, chalk, limestone, siltstone, clay, and lignite.Low7100%

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

Austin County beside the ground around it

Across Texas 0.5% of the land is rated high; none of Austin County's is. None of the 6 counties that border it has any moderate-potential ground either.

Share of land by USGS radon potential: Austin County, the 6 counties bordering it and Texas
AreaEPA zoneLow potentialModerate potentialHigh potential
Austin CountyZone 3100%NoneNone
Waller CountyZone 3100%NoneNone
Colorado CountyZone 3100%NoneNone
Washington CountyZone 3100%NoneNone
Fayette CountyZone 3100%NoneNone
Wharton CountyZone 3100%NoneNone
Fort Bend 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

Austin County, Local resources

Radon testing and mitigation in Austin County

What it means

Austin County, Questions

Questions about radon in Austin County

Are radon levels high in Austin County?

Over the 2008 to 2017 laboratory totals, 0.0% of the radon tests reported to CDC for Austin County, Texas were at or above 4 pCi/L, and the median reported pre-mitigation result was 0.1 pCi/L. Fort Bend County, the one bordering county with a figure over the 2007 to 2016 laboratory totals, reported 3.4% of its tests at or above 4 pCi/L.

Which counties border Austin County?

Austin County borders 6 counties: Waller County, Colorado County, Washington County, Fayette County, Wharton County and Fort Bend County.

Products

Austin County, Products

Testing a home in Austin County

No CDC figure names Austin County; the nearest county with one, Fort Bend County (39 miles away), reported 3.4% 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 Austin County.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Austin County homes, compared

Explore

Austin County, Bordering counties

Counties bordering Austin County

Calculated by Radon411

Austin County, Cities and towns

Cities and towns in Austin County

Austin County is growing: the Census Bureau puts it at 33,625 residents on July 1, 2025, up 11.6% from 30,133 in 2020. That works out to 52 people per square mile of land. Its largest town, Sealy, has 7,937 residents, 23.6% of the total. Together its 7 incorporated places hold 46.1% of those residents; the other 53.9% live outside any of them. CDC's 3 reported tests for 2006 to 2015 work out to 0.1 per 1,000 residents (2025 estimate), close to Texas' 0.1.

From Sealy to South Frydek, CDC publishes no figure by town: each reads Austin County's.

The cities and towns in Austin County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Sealy7,937+16.3%23.6%
Bellville4,379+4.1%13.0%
Wallis1,372+5.7%4.1%
San Felipe739+7.3%2.2%
Brazos Country537+4.5%1.6%
Industry298+11.6%0.9%
South Frydek237+9.7%0.7%

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).

Austin County, Homes

Homes in Austin County

Of Austin County's 14,086 homes, 71% are detached houses, against 65% across Texas; 22% are mobile homes. Half of its homes were built before 1991, close to Texas' 1990: 17% date from before 1960 and 36% from 2000 or later. Owners live in 77% of the occupied homes (Texas: 63%), so for most households a test and a fix are their own to order.

Homes in Austin County, Texas, 2019 to 2023
HomesAustin CountyTexas
Housing units14,08611,890,808
Detached houses71%65%
In buildings of 5 or more3%21%
Mobile homes22%7%
Built before 196017%13%
Built since 200036%37%
Middle year built19911990
Owner-occupied77%63%

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