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Radon Levels in Hamilton County, Texas

EPA puts Hamilton County in Zone 3, its lowest radon zone, and only 1 radon test from it is 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

  • Nearest county

    17.1%

    McLennan County, 55 miles

    McLennan
    17.1%
    Texas
    10.4%

    Share at 4+ pCi/L, 41 tests, 2007 to 2016

  • Ground above low

    None

    27.3 pts below Texas

    Hamilton
    0.0%
    Texas
    27.3%

    Share of land USGS rates moderate or high potential

  • Tests reported

    1

    Too few for a share

    Hamilton
    1
    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 Hamilton 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

Hamilton County, At a glance

Hamilton County at a glance

Predicted: EPA radon zone

EPA Zone 3: lower predicted potential

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

CDC holds 1 reported test for Hamilton County over the 2008 to 2017 laboratory totals, a result of 0.1 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Hamilton County beside the counties around it is how this page reads it.

What these figures count

Only 1 test was reported to CDC for Hamilton 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

Hamilton County, Compared

Hamilton County radon figures, compared

Calculated by Radon411

CDC's largest figure for Hamilton County rests on 1 test over the 2008 to 2017 laboratory totals, 0 of them at or above 4 pCi/L, so each test moves its share by 100.0 points and no rank or comparison is drawn from it. Results reached as high as 0.1 pCi/L, with a middle value of 0.1 pCi/L.

The nearest counties with a figure are McLennan County (55 miles away) at 17.1%, Bell County (59 miles away) at 14.3% and Williamson County (79 miles away) at 2.0%. 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 Hamilton 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 Hamilton 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
Coryell County, TXborders it520.0%0.8 pCi/L
The nearest Texas counties to Hamilton County with 30 or more tests, 2007 to 2016, laboratory
CountyDistanceTestsAt or above 4 pCi/LMedian
McLennan County55 mi4117.1%1.0 pCi/L
Bell County59 mi3514.3%1.1 pCi/L
Williamson County79 mi982.0%0.7 pCi/L
Tarrant County88 mi31210.6%0.9 pCi/L
Travis County96 mi4089.3%0.8 pCi/L
Dallas County107 mi6998.7%1.0 pCi/L
Denton County119 mi1817.2%0.9 pCi/L
Brazos County129 mi490.0%0.2 pCi/L
Hamilton County ten-year laboratory totals, against Texas' pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestTexas, pooledChange from the row before
2008 to 201710.0%0.1 pCi/L0.1 pCi/L10.2%Level
2007 to 201610.0%0.1 pCi/L0.1 pCi/L10.4%Level
2006 to 201510.0%0.1 pCi/L0.1 pCi/L11.0%Level
2005 to 201410.0%0.1 pCi/L0.1 pCi/L10.6%First on file

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

Hamilton County, Geology

The ground under Hamilton County

Predicted

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

USGS's geologic areas under Hamilton County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Central Texas/Gulf Coast 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.

Hamilton County beside the ground around it

Across Texas 0.5% of the land is rated high; none of Hamilton County's is. Of the 6 counties that border it, 1 has more moderate-potential ground, Lampasas County the most at 1.7%.

Share of land by USGS radon potential: Hamilton County, the 6 counties bordering it and Texas
AreaEPA zoneLow potentialModerate potentialHigh potential
Hamilton CountyZone 3100%NoneNone
Bosque CountyZone 3100%NoneNone
Erath CountyZone 3100%NoneNone
Coryell CountyZone 3100%NoneNone
Lampasas CountyZone 398.3%1.7%None
Comanche CountyZone 3100%NoneNone
Mills 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

Hamilton County, Local resources

Radon testing and mitigation in Hamilton 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

Hamilton County, Questions

Questions about radon in Hamilton County

Are radon levels high in Hamilton County?

Over the 2008 to 2017 laboratory totals, 0.0% of the radon tests reported to CDC for Hamilton County, Texas were at or above 4 pCi/L, and the median reported pre-mitigation result was 0.1 pCi/L. Of the 8 nearest counties with a figure, within 129 miles, the share of tests at or above 4 pCi/L runs from 0.0% to 17.1%.

Which counties border Hamilton County?

Hamilton County borders 6 counties: Bosque County, Erath County, Coryell County, Lampasas County, Comanche County and Mills County.

Products

Hamilton County, Products

Testing a home in Hamilton County

No CDC figure names Hamilton County; the nearest county with one, McLennan County (55 miles away), reported 17.1% 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 Hamilton County.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Hamilton County homes, compared

Explore

Hamilton County, Bordering counties

Counties bordering Hamilton County

Calculated by Radon411

Hamilton County, Cities and towns

Cities and towns in Hamilton County

Hamilton County is growing: the Census Bureau puts it at 8,680 residents on July 1, 2025, up 5.2% from 8,252 in 2020. That works out to 10 people per square mile of land. Its largest town, Hamilton, has 3,016 residents, 34.7% of the total. CDC's 1 reported test for 2008 to 2017 work out to 0.1 per 1,000 residents (2025 estimate), close to Texas' 0.1.

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

The cities and towns in Hamilton County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Hamilton3,016+4.0%34.7%
Hicoextends beyond Hamilton County1,496+12.3%Counted whole
Evantextends beyond Hamilton County467+1.7%Counted whole

3 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). A place that extends beyond Hamilton County is counted whole, so it has no share.

Hamilton County, Homes

Homes in Hamilton County

Hamilton County is a place of houses on their own lots: 88% of its 4,356 homes are detached single-family houses, against 65% across Texas. The homes are older than Texas' as a whole: half were built before 1967 (1990 for Texas), and 42% date from before 1960. 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 Hamilton County, Texas, 2019 to 2023
HomesHamilton CountyTexas
Housing units4,35611,890,808
Detached houses88%65%
In buildings of 5 or more1%21%
Mobile homes8%7%
Built before 196042%13%
Built since 200016%37%
Middle year built19671990
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.