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Radon Levels in Lamar County, Texas

EPA puts Lamar 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

    7.7%

    Collin County, 67 miles

    Collin
    7.7%
    Texas
    10.4%

    Share at 4+ pCi/L, 284 tests, 2007 to 2016

  • Ground above low

    72.8%

    45.5 pts above Texas

    Lamar
    72.8%
    Texas
    27.3%

    Share of land USGS rates moderate or high potential

  • Tests reported

    6

    Too few for a share

    Lamar
    6
    Needed
    30

    2007 to 2016, 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 Lamar 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

Lamar County, At a glance

Lamar County at a glance

Predicted: EPA radon zone

EPA Zone 3: lower predicted potential

is EPA's lowest class, and its forecast for Lamar 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: Moderate across 73% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

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

CDC holds 1 reported test for Lamar County over the 2008 to 2017 laboratory totals, a result of 2.2 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Lamar County beside the counties around it is how this page reads it.

What these figures count

Only 1 test was reported to CDC for Lamar 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

Lamar County, Compared

Lamar County radon figures, compared

Calculated by Radon411

CDC's largest figure for Lamar County rests on 6 tests over the 2007 to 2016 laboratory totals, 0 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 2.2 pCi/L, with a middle value of 0.3 pCi/L.

The nearest counties with a figure are Collin County (67 miles away) at 7.7%, Smith County (91 miles away) at 9.1% and Dallas County (93 miles away) at 8.7%. 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 Lamar County in Zone 3, its lowest label: a predicted county average under 2 pCi/L. USGS geology rates 73% of the county's land moderate radon potential.

Texas, the United States and the counties around Lamar 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
Choctaw County, OKborders it2100.0%4.8 pCi/L
Bryan County, OKborders it10.0%0.6 pCi/L
Fannin County, TXborders it10.0%0.9 pCi/L
The nearest Texas counties to Lamar County with 30 or more tests, 2007 to 2016, laboratory
CountyDistanceTestsAt or above 4 pCi/LMedian
Collin County67 mi2847.7%1.0 pCi/L
Smith County91 mi339.1%0.8 pCi/L
Dallas County93 mi6998.7%1.0 pCi/L
Denton County95 mi1817.2%0.9 pCi/L
Tarrant County117 mi31210.6%0.9 pCi/L
McLennan County174 mi4117.1%1.0 pCi/L
Brazos County212 mi490.0%0.2 pCi/L
Bell County213 mi3514.3%1.1 pCi/L
Lamar County ten-year laboratory totals, against Texas' pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestTexas, pooledChange from the row before
2008 to 201710.0%2.2 pCi/L2.2 pCi/L10.2%Level
2007 to 201660.0%0.3 pCi/L2.2 pCi/L10.4%Level
2006 to 201560.0%0.3 pCi/L2.2 pCi/L11.0%Level
2005 to 201460.0%0.3 pCi/L2.2 pCi/L10.6%First on file

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

Lamar County, Geology

The ground under Lamar County

Predicted

USGS's geologic map splits Lamar County: 72.8% of its land is moderate radon potential and 27.2% low. The map puts 72.8% of Lamar County in the area it calls Cretaceous Gulfian series and 27.2% in East Texas Province. USGS gives the first a radon index of 10, in the moderate band (9 to 11), and the second 6, in the low band (5 to 8).

USGS's geologic areas under Lamar County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Cretaceous Gulfian seriesCretaceous sandstone, shale, limestone, siltstone.Moderate1072.8%
East Texas ProvinceCretaceous through Quaternary marine sandstone, shale, chalk, limestone, siltstone, clay, and lignite.Low627.2%

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

Lamar County beside the ground around it

Across Texas 0.5% of the land is rated high; none of Lamar County's is. Of the 5 counties that border it, 1 has more moderate-potential ground, Fannin County the most at 82.5%.

Share of land by USGS radon potential: Lamar County, the 5 counties bordering it and Texas
AreaEPA zoneLow potentialModerate potentialHigh potential
Lamar CountyZone 327.2%72.8%None
Delta CountyZone 3100%NoneNone
Choctaw County, OKZone 376.8%23.2%None
Fannin CountyZone 317.5%82.5%None
Red River CountyZone 379.4%20.6%None
Bryan County, OKZone 345.8%54.3%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

Lamar County, Local resources

Radon testing and mitigation in Lamar 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

Lamar County, Questions

Questions about radon in Lamar County

Are radon levels high in Lamar County?

Over the 2008 to 2017 laboratory totals, 0.0% of the radon tests reported to CDC for Lamar County, Texas were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.2 pCi/L. Of the 8 nearest counties with a figure, within 213 miles, the share of tests at or above 4 pCi/L runs from 0.0% to 17.1%.

Which counties border Lamar County?

Lamar County borders 5 counties: Delta County, TX, Choctaw County, OK, Fannin County, TX, Red River County, TX and Bryan County, OK.

Products

Lamar County, Products

Testing a home in Lamar County

No CDC figure names Lamar County; the nearest county with one, Collin County (67 miles away), reported 7.7% 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 Lamar County.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Lamar County homes, compared

Explore

Lamar County, Bordering counties

Counties bordering Lamar County

Calculated by Radon411

Lamar County, Cities and towns

Cities and towns in Lamar County

The Census Bureau estimates 51,503 residents in Lamar County for July 1, 2025, 1,372 more than in 2020 (+2.7%). That works out to 57 people per square mile of land. Its largest town, Paris, has 25,205 residents, 48.9% of the total. CDC's 6 reported tests for 2007 to 2016 work out to 0.1 per 1,000 residents (2025 estimate), close to Texas' 0.1.

From Paris to Sun Valley, CDC publishes no figure by town: each reads Lamar County's.

The cities and towns in Lamar County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Paris25,205+2.9%48.9%
Reno3,575+3.2%6.9%
Blossom1,493+5.8%2.9%
Roxton556+1.3%1.1%
Deportextends beyond Lamar County552LevelCounted whole
Toco92+1.1%0.2%
Sun Valley77+8.5%0.1%

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

Lamar County, Homes

Homes in Lamar County

Of Lamar County's 22,744 homes, 75% are detached houses, against 65% across Texas; 9% are in buildings of five or more homes. Half of its homes were built before 1985, close to Texas' 1990: 14% date from before 1960 and 27% from 2000 or later. 66% 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 Lamar County, Texas, 2019 to 2023
HomesLamar CountyTexas
Housing units22,74411,890,808
Detached houses75%65%
In buildings of 5 or more9%21%
Mobile homes7%7%
Built before 196014%13%
Built since 200027%37%
Middle year built19851990
Owner-occupied66%63%

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