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Radon Levels in McLennan County, Texas

EPA puts McLennan County in Zone 3, its lowest radon zone, and 23.3% of its 30 reported radon tests (2008 to 2017, laboratory totals) were at or above 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

    23.3%

    13.1 pts above TX

    McLennan
    23.3%
    Texas
    10.2%

    30 tests, 2008 to 2017

  • Median result

    1.1pCi/L

    Below action level

    McLennan
    1.1 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    30

    21st of 22 by tests

    McLennan
    30
    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

    3 of 22

    Top quarter

    McLennan
    23.3%
    Randall
    69.0%

    By share, of 22 with 30+ tests

Read a result for McLennan County

Starts at McLennan County's median, 1.1 pCi/L

1.1pCi/L

EPA’s own thresholds; the figures are the area’s, never this home’s.

EPA’s reading of 1.1 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. McLennan County's median reported result, 2008 to 2017.

Interpret this reading

The data

McLennan County, At a glance

McLennan County at a glance

Predicted: EPA radon zone

EPA Zone 3: lower predicted potential

is EPA's lowest class, and its forecast for McLennan 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 72% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

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

Reported results by concentration band, McLennan County, 2008 to 2017, laboratory
Under 2 pCi/L: 74%2 to 4 pCi/L: 3%4 pCi/L and above: 23%

Of 30 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, McLennan County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L2273.3%
2 to 4 pCi/L13.3%
4 pCi/L and above723.3%
What these figures count

These are the 30 tests reported to CDC for McLennan 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

McLennan County, Compared

McLennan County radon figures, compared

Calculated by Radon411

McLennan County's 30 reported tests over the 2008 to 2017 laboratory totals had a middle value of 1.1 pCi/L and a maximum of 13.8 pCi/L, and 23.3% reached 4 pCi/L. Texas as a whole (138 Texas counties, pooled) comes to 10.2%: 13.1 points lower than here.

Among its state's counties it ranks 3rd of 22 Texas counties with 30 or more tests for the same period. Statewide for the same period, Randall County reported the highest share (69.0%) and Nueces County the lowest (0.0%).

Below the action level, 22 tests (73.3%) came in under 2 pCi/L, against 80.3% statewide, and 1 tests (3.3%) fell between 2 and 4, against 9.6% statewide. CDC's ten-year totals for McLennan County went from 36 tests (2005 to 2014) to 30 (2008 to 2017), the share going from 16.7% to 23.3%.

EPA's 1993 zone map puts McLennan County in Zone 3, a predicted county average under 2 pCi/L. USGS geology rates 72% of the county's land low radon potential.

Bell County, the one bordering county with a figure for the same period, reported 16.7%.

McLennan County against Texas, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from McLennan County
McLennan County3023.3%1.1 pCi/LThis county
Texas, pooled138 counties, pooled4,61510.2%Not pooled−13.1 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled+12.4 points
Randall Countyhighest in the state8769.0%6.1 pCi/L+45.7 points
Nueces Countylowest in the state430.0%0.6 pCi/L−23.3 points
Bell County, TXborders it3016.7%1.3 pCi/L−6.6 points
Coryell County, TXborders it40.0%0.8 pCi/L−23.3 points
Hill County, TXborders it50.0%0.1 pCi/L−23.3 points
Where McLennan County's reported results fell, 2008 to 2017, laboratory, beside Texas and the United States
ResultMcLennan County testsMcLennan County shareTexas shareU.S. shareAgainst Texas
Under 2 pCi/L2273.3%80.3%39.6%−7.0 points
2 to 4 pCi/L13.3%9.6%24.7%−6.3 points
4 pCi/L and above723.3%10.2%35.7%+13.1 points
McLennan 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
Randall County1 of 228769.0%6.1 pCi/L
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
McLennan County ten-year laboratory totals, against Texas' pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestTexas, pooledChange from the row before
2008 to 20173023.3%1.1 pCi/L13.8 pCi/L10.2%+6.2 points
2007 to 20164117.1%1.0 pCi/L13.8 pCi/L10.4%Level
2006 to 20154117.1%1.0 pCi/L13.8 pCi/L11.0%+0.4 points
2005 to 20143616.7%0.9 pCi/L13.8 pCi/L10.6%First on file

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

McLennan County, Geology

The ground under McLennan County

Predicted

USGS's geologic map splits McLennan County: 72.0% of its land is low radon potential and 28.0% moderate. The map puts 42.1% of McLennan County in the area it calls East Texas Province and 29.8% in Central Texas/Gulf Coast Plain, with one smaller area 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 McLennan County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
East Texas ProvinceCretaceous through Quaternary marine sandstone, shale, chalk, limestone, siltstone, clay, and lignite.Low642.1%
Central Texas/Gulf Coast PlainCretaceous through Quaternary marine sandstone, shale, chalk, limestone, siltstone, clay, and lignite.Low729.8%
Cretaceous Gulfian seriesCretaceous sandstone, shale, limestone, siltstone.Moderate1028.0%

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

McLennan County beside the ground around it

Across Texas 0.5% of the land is rated high; none of McLennan County's is. Of the 6 counties that border it, 1 has more moderate-potential ground, Hill County the most at 54.9%.

Share of land by USGS radon potential: McLennan County, the 6 counties bordering it and Texas
AreaEPA zoneLow potentialModerate potentialHigh potential
McLennan CountyZone 372.0%28.0%None
Falls CountyZone 399.6%0.4%None
Hill CountyZone 345.1%54.9%None
Bosque CountyZone 3100%NoneNone
Coryell CountyZone 3100%NoneNone
Bell CountyZone 382.2%17.8%None
Limestone 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

McLennan County, Local resources

Radon testing and mitigation in McLennan 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

McLennan County, Questions

Questions about radon in McLennan County

Are radon levels high in McLennan County?

Over the 2008 to 2017 laboratory totals, 23.3% of the radon tests reported to CDC for McLennan County, Texas were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.1 pCi/L. Of 22 Texas counties with 30 or more tests for the same period, 2 reported a higher share; pooled, the state comes to 10.2%.

Which counties border McLennan County?

McLennan County borders 6 counties: Falls County, Hill County, Bosque County, Coryell County, Bell County and Limestone County.

Products

McLennan County, Products

Testing a home in McLennan County

In McLennan County, 23.3% of 30 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 McLennan County.

Test kits and monitors3

See every kit and monitor

Best radon monitors for McLennan County homes, compared

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McLennan County, Bordering counties

Counties bordering McLennan County

Calculated by Radon411

McLennan County, Cities and towns

Cities and towns in McLennan County

The Census Bureau estimates 272,020 residents in McLennan County for July 1, 2025, 10,831 more than in 2020 (+4.1%). That works out to 262 people per square mile of land. Waco alone is home to 147,788 of them, 54.3% of the total. CDC's 30 reported tests for 2008 to 2017 work out to 0.1 per 1,000 residents (2025 estimate), close to Texas' 0.1.

From Waco to Ross, CDC publishes no figure by town: each reads McLennan County's.

The 12 largest cities and towns in McLennan County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Waco147,788+5.2%54.3%
Hewitt16,754+4.3%6.2%
Robinson13,028+4.5%4.8%
Bellmead10,592+0.9%3.9%
Woodway9,753+3.5%3.6%
Lacy-Lakeview7,240+0.7%2.7%
McGregorextends beyond McLennan County6,405+18.1%Counted whole
West2,629+2.7%1.0%
Martextends beyond McLennan County1,847+3.4%Counted whole
Beverly Hills1,835−2.0%0.7%
Lorena1,817+2.1%0.7%
Moody1,650+6.5%0.6%
  • Bruceville-Eddy (part)
  • Valley Mills (part)
  • Gholson
  • Riesel
  • Crawford
  • Golinda (part)
  • Hallsburg
  • Leroy
  • Ross

21 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 McLennan County is counted whole, so it has no share.

McLennan County, Homes

Homes in McLennan County

Of McLennan County's 107,194 homes, 67% are detached houses, against 65% across Texas; 18% are in buildings of five or more homes. The homes are older than Texas' as a whole: half were built before 1982 (1990 for Texas), and 21% date from before 1960. 61% 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 McLennan County, Texas, 2019 to 2023
HomesMcLennan CountyTexas
Housing units107,19411,890,808
Detached houses67%65%
In buildings of 5 or more18%21%
Mobile homes6%7%
Built before 196021%13%
Built since 200027%37%
Middle year built19821990
Owner-occupied61%63%

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