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Radon in Texas: radon map by county

EPA's Map of Radon Zones puts 0 of Texas's 254 counties in Zone 1 (predicted average indoor radon above 4 pCi/L), 39 in Zone 2 and 215 in Zone 3. Of 2,382 building tests that radon laboratories reported for 2008 to 2017, 11.3% were at or above EPA's 4 pCi/L action level, against 36.5% nationally (number 40 of 42 states with 1,000+ tests). The highest county share is Randall County (69% of 58 tests).

0
counties in Zone 1 (above 4 pCi/L predicted)
39
counties in Zone 2 (2 to 4)
215
counties in Zone 3 (below 2)
11.3%
of 2,382 lab tests at or above 4 pCi/L

Radon by county in Texas

EPA radon zone and radon test results for each county in Texas
CountyEPA zoneLab testsMedian4+ pCi/L
Anderson County Zone 3n/an/an/a
Andrews County Zone 3n/an/an/a
Angelina County Zone 330.10%
Aransas County Zone 321.50%
Archer County Zone 3n/an/an/a
Armstrong County Zone 2n/an/an/a
Atascosa County Zone 311.10%
Austin County Zone 320.10%
Bailey County Zone 2n/an/an/a
Bandera County Zone 3n/an/an/a
Bastrop County Zone 356.561.5%
Baylor County Zone 3n/an/an/a
Bee County Zone 3n/an/an/a
Bell County Zone 3201.316.7%
Bexar County Zone 3890.66.5%
Blanco County Zone 320.20%
Borden County Zone 3n/an/an/a
Bosque County Zone 3n/an/an/a
Bowie County Zone 3n/an/an/a
Brazoria County Zone 3220.36.3%
Brazos County Zone 3120.50%
Brewster County Zone 243.050%
Briscoe County Zone 3n/an/an/a
Brooks County Zone 3n/an/an/a
Brown County Zone 321.00%
Burleson County Zone 3n/an/an/a
Burnet County Zone 3427.471.4%
Caldwell County Zone 321.10%
Calhoun County Zone 3n/an/an/a
Callahan County Zone 3n/an/an/a
Cameron County Zone 360.70%
Camp County Zone 3n/an/an/a
Carson County Zone 2136.2100%
Cass County Zone 311.60%
Castro County Zone 213.60%
Chambers County Zone 330.10%
Cherokee County Zone 310.10%
Childress County Zone 311.10%
Clay County Zone 3n/an/an/a
Cochran County Zone 3n/an/an/a
Coke County Zone 3n/an/an/a
Coleman County Zone 3n/an/an/a
Collin County Zone 31731.07.6%
Collingsworth County Zone 3112.6100%
Colorado County Zone 311.50%
Comal County Zone 3100.94.5%
Comanche County Zone 3n/an/an/a
Concho County Zone 3n/an/an/a
Cooke County Zone 311.60%
Coryell County Zone 320.80%
Cottle County Zone 3n/an/an/a
Crane County Zone 3n/an/an/a
Crockett County Zone 3n/an/an/a
Crosby County Zone 2n/an/an/a
Culberson County Zone 2n/an/an/a
Dallam County Zone 214.2100%
Dallas County Zone 33810.98.4%
Dawson County Zone 313.025%
Deaf Smith County Zone 248.283.3%
Delta County Zone 3n/an/an/a
Denton County Zone 31030.96.8%
DeWitt County Zone 310.20%
Dickens County Zone 3n/an/an/a
Dimmit County Zone 3n/an/an/a
Donley County Zone 214.0100%
Duval County Zone 3n/an/an/a
Eastland County Zone 321.40%
Ector County Zone 380.70%
Edwards County Zone 3n/an/an/a
El Paso County Zone 3260.70%
Ellis County Zone 3413.566.7%
Erath County Zone 3n/an/an/a
Falls County Zone 3n/an/an/a
Fannin County Zone 310.90%
Fayette County Zone 330.10%
Fisher County Zone 3n/an/an/a
Floyd County Zone 2n/an/an/a
Foard County Zone 3n/an/an/a
Fort Bend County Zone 3680.22.9%
Franklin County Zone 3n/an/an/a
Freestone County Zone 350.90%
Frio County Zone 3n/an/an/a
Gaines County Zone 3n/an/an/a
Galveston County Zone 3370.20%
Garza County Zone 2n/an/an/a
Gillespie County Zone 350.616.7%
Glasscock County Zone 3n/an/an/a
Goliad County Zone 3n/an/an/a
Gonzales County Zone 310.10%
Gray County Zone 221.90%
Grayson County Zone 3121.15%
Gregg County Zone 390.90%
Grimes County Zone 310.10%
Guadalupe County Zone 320.60%
Hale County Zone 287.881.8%
Hall County Zone 3n/an/an/a
Hamilton County Zone 310.10%
Hansford County Zone 2n/an/an/a
Hardeman County Zone 3n/an/an/a
Hardin County Zone 330.80%
Harris County Zone 33000.42.9%
Harrison County Zone 320.20%
Hartley County Zone 226.150%
Haskell County Zone 3n/an/an/a
Hays County Zone 370.517.4%
Hemphill County Zone 213.90%
Henderson County Zone 310.80%
Hidalgo County Zone 370.80%
Hill County Zone 340.10%
Hockley County Zone 2n/an/an/a
Hood County Zone 350.70%
Hopkins County Zone 315.0100%
Houston County Zone 312.20%
Howard County Zone 311.50%
Hudspeth County Zone 2n/an/an/a
Hunt County Zone 332.025%
Hutchinson County Zone 242.720%
Irion County Zone 3n/an/an/a
Jack County Zone 3n/an/an/a
Jackson County Zone 310.10%
Jasper County Zone 310.10%
Jeff Davis County Zone 241.128.6%
Jefferson County Zone 3110.14.3%
Jim Hogg County Zone 3n/an/an/a
Jim Wells County Zone 310.10%
Johnson County Zone 3140.80%
Jones County Zone 310.70%
Karnes County Zone 3n/an/an/a
Kaufman County Zone 350.50%
Kendall County Zone 345.771.4%
Kenedy County Zone 3n/an/an/a
Kent County Zone 3n/an/an/a
Kerr County Zone 340.90%
Kimble County Zone 312.10%
King County Zone 3n/an/an/a
Kinney County Zone 3n/an/an/a
Kleberg County Zone 3n/an/an/a
Knox County Zone 3n/an/an/a
La Salle County Zone 3n/an/an/a
Lamar County Zone 312.20%
Lamb County Zone 2n/an/an/a
Lampasas County Zone 3n/an/an/a
Lavaca County Zone 320.10%
Lee County Zone 3n/an/an/a
Leon County Zone 3n/an/an/a
Liberty County Zone 311.20%
Limestone County Zone 3n/an/an/a
Lipscomb County Zone 217.3100%
Live Oak County Zone 3n/an/an/a
Llano County Zone 251.50%
Loving County Zone 3n/an/an/a
Lubbock County Zone 2774.855.7%
Lynn County Zone 2n/an/an/a
Madison County Zone 311.50%
Marion County Zone 3n/an/an/a
Martin County Zone 3n/an/an/a
Mason County Zone 2n/an/an/a
Matagorda County Zone 330.133.3%
Maverick County Zone 310.10%
McCulloch County Zone 3n/an/an/a
McLennan County Zone 3141.123.3%
McMullen County Zone 3n/an/an/a
Medina County Zone 320.50%
Menard County Zone 3n/an/an/a
Midland County Zone 3270.71%
Milam County Zone 3n/an/an/a
Mills County Zone 3n/an/an/a
Mitchell County Zone 3n/an/an/a
Montague County Zone 350.112.5%
Montgomery County Zone 3640.83.2%
Moore County Zone 224.7100%
Morris County Zone 310.90%
Motley County Zone 3n/an/an/a
Nacogdoches County Zone 311.00%
Navarro County Zone 340.80%
Newton County Zone 3n/an/an/a
Nolan County Zone 320.90%
Nueces County Zone 3160.60%
Ochiltree County Zone 2112.1100%
Oldham County Zone 2n/an/an/a
Orange County Zone 390.80%
Palo Pinto County Zone 3n/an/an/a
Panola County Zone 310.60%
Parker County Zone 3171.111.1%
Parmer County Zone 2110.6100%
Pecos County Zone 3n/an/an/a
Polk County Zone 3125.5100%
Potter County Zone 2321.423%
Presidio County Zone 2n/an/an/a
Rains County Zone 3n/an/an/a
Randall County Zone 2586.169%
Reagan County Zone 3n/an/an/a
Real County Zone 3n/an/an/a
Red River County Zone 3n/an/an/a
Reeves County Zone 2n/an/an/a
Refugio County Zone 311.20%
Roberts County Zone 2n/an/an/a
Robertson County Zone 320.80%
Rockwall County Zone 381.218.8%
Runnels County Zone 310.70%
Rusk County Zone 320.40%
Sabine County Zone 3n/an/an/a
San Augustine County Zone 3n/an/an/a
San Jacinto County Zone 311.733.3%
San Patricio County Zone 3n/an/an/a
San Saba County Zone 3n/an/an/a
Schleicher County Zone 3n/an/an/a
Scurry County Zone 3111.1100%
Shackelford County Zone 311.00%
Shelby County Zone 3n/an/an/a
Sherman County Zone 211.30%
Smith County Zone 3420.85.8%
Somervell County Zone 3n/an/an/a
Starr County Zone 311.20%
Stephens County Zone 316.3100%
Sterling County Zone 3n/an/an/a
Stonewall County Zone 3n/an/an/a
Sutton County Zone 3n/an/an/a
Swisher County Zone 227.8100%
Tarrant County Zone 31930.913%
Taylor County Zone 3100.87.1%
Terrell County Zone 2n/an/an/a
Terry County Zone 3n/an/an/a
Throckmorton County Zone 3n/an/an/a
Titus County Zone 3n/an/an/a
Tom Green County Zone 352.033.3%
Travis County Zone 31940.99.2%
Trinity County Zone 3n/an/an/a
Tyler County Zone 3n/an/an/a
Upshur County Zone 350.90%
Upton County Zone 3n/an/an/a
Uvalde County Zone 3n/an/an/a
Val Verde County Zone 3n/an/an/a
Van Zandt County Zone 330.10%
Victoria County Zone 330.60%
Walker County Zone 330.50%
Waller County Zone 330.10%
Ward County Zone 3n/an/an/a
Washington County Zone 31n/an/a
Webb County Zone 350.60%
Wharton County Zone 310.50%
Wheeler County Zone 321.40%
Wichita County Zone 350.70%
Wilbarger County Zone 312.60%
Willacy County Zone 3n/an/an/a
Williamson County Zone 3820.71.9%
Wilson County Zone 310.10%
Winkler County Zone 3n/an/an/a
Wise County Zone 320.90%
Wood County Zone 3n/an/an/a
Yoakum County Zone 311.10%
Young County Zone 3n/an/an/a
Zapata County Zone 310.10%
Zavala County Zone 3n/an/an/a

Lab tests: buildings tested by radon laboratories, 2008 to 2017; median in pCi/L; “4+ pCi/L” is the share of tests at or above EPA's action level. n/a: no value on file (no tests, or too few to report).

What the zones mean

Zone 1 counties have a predicted average indoor radon screening level above 4 pCi/L, Zone 2 from 2 to 4 pCi/L and Zone 3 below 2 pCi/L. The prediction is from 1993 indoor measurements, geology, aerial radioactivity, soils and foundation types. EPA: “This map should not be used to determine if individual homes need to be tested.” EPA recommends fixing a home at 4 pCi/L or more and considering a fix between 2 and 4 pCi/L, because there is no known safe level of exposure.

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Radon in Texas: questions

What radon zone is Texas?

EPA's 1993 map does not give states one zone; it zones each county. In Texas, 0 counties are Zone 1, 39 Zone 2 and 215 Zone 3. EPA says the map "should not be used to determine if individual homes need to be tested".

Which Texas counties have the highest radon levels?

By the share of laboratory tests at or above 4 pCi/L for 2008 to 2017 (counties with 20 or more tests): Randall County 69% (median 6.1 pCi/L, 58 tests); Lubbock County 55.7% (median 4.8 pCi/L, 77 tests); Potter County 23% (median 1.4 pCi/L, 32 tests); Bell County 16.7% (median 1.3 pCi/L, 20 tests); Tarrant County 13% (median 0.9 pCi/L, 193 tests).

How common is high radon in Texas?

11.3% of the 2,382 tests in the laboratory data for Texas (2008 to 2017) were at or above 4 pCi/L; the national share was 36.5%. Buildings are tested by choice, often because of a sale or a concern, so the share describes the tests on file, not every home.

Should I test for radon in Texas?

Yes. EPA recommends testing every home no matter where it is, fixing it at 4 pCi/L or more and considering a fix between 2 and 4 pCi/L, because there is no known safe level of radon exposure.

States bordering Texas

Radon in Arkansas (0 of 75 in Zone 1)Radon in Louisiana (0 of 64 in Zone 1)Radon in New Mexico (7 of 33 in Zone 1)Radon in Oklahoma (0 of 77 in Zone 1)

Other free hazard lookups

All of these, plus wetlands, FEMA hazard ratings and the federal contamination lists, are in the Environmental Records Report for any US address ($29).

Superfund sites in Texas · Radon map of every state

Data compiled 2026-10-20. County-level screening information, not a radon measurement of any building.