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Radon Levels in Matagorda County, Texas

EPA puts Matagorda County in Zone 3, its lowest radon zone, and only 6 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

    6.3%

    Brazoria County

    Brazoria
    6.3%

    1 of 4 neighbours have 30+ tests, 2007 to 2016

  • Nearest county

    6.3%

    Brazoria County, 42 miles

    Brazoria
    6.3%
    Texas
    10.4%

    Share at 4+ pCi/L, 32 tests, 2007 to 2016

  • Ground above low

    None

    27.3 pts below Texas

    Matagorda
    0.0%
    Texas
    27.3%

    Share of land USGS rates moderate or high potential

  • Tests reported

    6

    Too few for a share

    Matagorda
    6
    Needed
    30

    2008 to 2017, 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 Matagorda 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

Matagorda County, At a glance

Matagorda County at a glance

Predicted: EPA radon zone

EPA Zone 3: lower predicted potential

is EPA's lowest class, and its forecast for Matagorda 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 85% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

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

CDC holds 6 reported tests for Matagorda 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). Matagorda County beside the counties around it is how this page reads it.

What these figures count

Only 6 tests were reported to CDC for Matagorda 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

Matagorda County, Compared

Matagorda County radon figures, compared

Calculated by Radon411

CDC's largest figure for Matagorda County rests on 6 tests over the 2008 to 2017 laboratory totals, 2 of them at or above 4 pCi/L, so each test moves its share by 16.7 points and no rank or comparison is drawn from it. Results reached as high as 10.8 pCi/L, with a middle value of 0.1 pCi/L.

Brazoria County, the one bordering county with a figure over the 2007 to 2016 laboratory totals, reported 6.3% of its tests at or above 4 pCi/L. Farther out, Fort Bend County (51 miles away) at 3.4%, Galveston County (75 miles away) at 0.0% and Harris County (81 miles away) at 3.1% 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 Matagorda County in Zone 3, its lowest label: a predicted county average under 2 pCi/L. USGS geology rates 85% of the county's land low radon potential.

Texas, the United States and the counties around Matagorda 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
Brazoria County, TXborders it326.3%0.3 pCi/L
Wharton County, TXborders it90.0%0.5 pCi/L
Jackson County, TXborders it10.0%0.1 pCi/L
The nearest Texas counties to Matagorda County with 30 or more tests, 2007 to 2016, laboratory
CountyDistanceTestsAt or above 4 pCi/LMedian
Brazoria County42 mi326.3%0.3 pCi/L
Fort Bend County51 mi1173.4%0.2 pCi/L
Galveston County75 mi830.0%0.2 pCi/L
Harris County81 mi7753.1%0.2 pCi/L
Montgomery County106 mi857.1%0.6 pCi/L
Nueces County123 mi450.0%0.6 pCi/L
Brazos County128 mi490.0%0.2 pCi/L
Travis County149 mi4089.3%0.8 pCi/L
Matagorda County ten-year laboratory totals, against Texas' pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestTexas, pooledChange from the row before
2008 to 2017633.3%0.1 pCi/L10.8 pCi/L10.2%Level
2007 to 2016633.3%0.1 pCi/L10.8 pCi/L10.4%Level
2006 to 2015633.3%0.1 pCi/L10.8 pCi/L11.0%Level
2005 to 2014633.3%0.1 pCi/L10.8 pCi/L10.6%First on file

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

Matagorda County, Geology

The ground under Matagorda County

Predicted

USGS's geologic map puts all of Matagorda County's mapped land in one class: low radon potential. 84.5% 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 Matagorda County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Coastal PlainCretaceous through Quaternary marine sandstone, shale, chalk, limestone, siltstone, clay, and lignite.Low784.5%

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

Matagorda County beside the ground around it

Across Texas 0.5% of the land is rated high; none of Matagorda County's is. None of the 4 counties that border it has any moderate-potential ground either.

Share of land by USGS radon potential: Matagorda County, the 4 counties bordering it and Texas
AreaEPA zoneLow potentialModerate potentialHigh potential
Matagorda CountyZone 384.5%NoneNone
Wharton CountyZone 3100%NoneNone
Jackson CountyZone 3100%NoneNone
Brazoria CountyZone 398.0%NoneNone
Calhoun CountyZone 375.2%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

Matagorda County, Local resources

Radon testing and mitigation in Matagorda 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

Matagorda County, Questions

Questions about radon in Matagorda County

Are radon levels high in Matagorda County?

Over the 2008 to 2017 laboratory totals, 33.3% of the radon tests reported to CDC for Matagorda County, Texas were at or above 4 pCi/L, and the median reported pre-mitigation result was 0.1 pCi/L. Brazoria County, the one bordering county with a figure over the 2007 to 2016 laboratory totals, reported 6.3% of its tests at or above 4 pCi/L.

Which counties border Matagorda County?

Matagorda County borders 4 counties: Wharton County, Jackson County, Brazoria County and Calhoun County.

Products

Matagorda County, Products

Testing a home in Matagorda County

No CDC figure names Matagorda County; the nearest county with one, Brazoria County (42 miles away), reported 6.3% 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 Matagorda County.

Test kits and monitors3

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Best radon monitors for Matagorda County homes, compared

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Matagorda County, Bordering counties

Counties bordering Matagorda County

Calculated by Radon411

Matagorda County, Cities and towns

Cities and towns in Matagorda County

Matagorda County's population has barely moved since 2020: 36,463 residents on July 1, 2025 against 36,287 then, by the Census Bureau's estimates. That works out to 33 people per square mile of land. Its largest town, Bay City, has 17,488 residents, 48.0% of the total. Together its 2 incorporated places hold 59.9% of those residents; the other 40.1% live outside any of them. CDC's 6 reported tests for 2008 to 2017 work out to 0.2 per 1,000 residents (2025 estimate), close to Texas' 0.1.

From Bay City to Palacios, CDC publishes no figure by town: each reads Matagorda County's.

The cities and towns in Matagorda County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Bay City17,488−3.1%48.0%
Palacios4,370−0.5%12.0%

2 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).

Matagorda County, Homes

Homes in Matagorda County

Of Matagorda County's 18,871 homes, 71% are detached houses, against 65% across Texas; 13% are mobile homes. The homes are older than Texas' as a whole: half were built before 1978 (1990 for Texas), and 18% date from before 1960. 69% 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 Matagorda County, Texas, 2019 to 2023
HomesMatagorda CountyTexas
Housing units18,87111,890,808
Detached houses71%65%
In buildings of 5 or more9%21%
Mobile homes13%7%
Built before 196018%13%
Built since 200022%37%
Middle year built19781990
Owner-occupied69%63%

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