Short-term kitempowerDX
Standard Radon Test short-term mail-in radon test kit
- Lab fee included
Method: Passive sampler
In home: 48 to 96 hours
Locations and reports
Radon Levels in Webb County, Texas
EPA puts Webb 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
Nearest county
0.0%
Nueces County, 105 miles
- Nueces
- 0.0%
- Texas
- 10.4%
Share at 4+ pCi/L, 45 tests, 2007 to 2016
Ground above low
None
27.3 pts below Texas
- Webb
- 0.0%
- Texas
- 27.3%
Share of land USGS rates moderate or high potential
Tests reported
7
Too few for a share
- Webb
- 7
- Needed
- 30
2005 to 2014, laboratory
EPA radon zone
Zone 3
Lower potential
- 1
- 2
- Zone 3
1 highest, 3 lowest
EPA predicts under 2 pCi/L indoors
Read a result for Webb County
Starts at EPA's action level
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
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 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.
The data
Webb County, At a glance
Webb County at a glance
Predicted: EPA radon zone
EPA Zone 3: lower predicted potential
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 Webb County, 2008 to 2017, laboratory
CDC holds 6 reported tests for Webb County over the 2008 to 2017 laboratory totals, with a median of 0.6 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Webb County beside the counties around it is how this page reads it.
What these figures count
Only 6 tests were reported to CDC for Webb 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).
Webb County, Compared
Webb County radon figures, compared
Calculated by Radon411CDC's largest figure for Webb County rests on 7 tests over the 2005 to 2014 laboratory totals, 0 of them at or above 4 pCi/L, so each test moves its share by 14.3 points and no rank or comparison is drawn from it. Results reached as high as 1.6 pCi/L, with a middle value of 0.7 pCi/L.
The nearest counties with a figure are Nueces County (105 miles away) at 0.0%, Bexar County (126 miles away) at 6.6% and Travis County (201 miles away) at 9.3%. 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 Webb 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.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Webb County, Geology
The ground under Webb County
PredictedUSGS's geologic map puts all of Webb County's mapped land in one class: low radon potential. All of it lies in the area the map calls South Texas Plain, to which USGS gives a radon index of 7, in the low band (5 to 8).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| South Texas Plain | Cretaceous through Quaternary marine sandstone, shale, chalk, limestone, siltstone, clay, and lignite. | Low | 7 | 99.9% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Webb County beside the ground around it
Across Texas 0.5% of the land is rated high; none of Webb County's is. None of the 7 counties that border it has any moderate-potential ground either.
The map rates the ground, not the air in any home.
Local help
Webb County, Local resources
Radon testing and mitigation in Webb County
- Texas Radon GroupTexas Radon Group, run by Texas Tech University, does not license radon professionals and offers free or discounted test kits, and answers questions about testing and mitigation in Texas.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsThe program says:
The Texas Radon Group offers free radon test kits for Texas individuals who qualify.
- Compare kits
- Professionals in Texas7 professionals are listed in Texas.
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
Webb County, Questions
Questions about radon in Webb County
Are radon levels high in Webb County?
Over the 2008 to 2017 laboratory totals, 0.0% of the radon tests reported to CDC for Webb County, Texas were at or above 4 pCi/L, and the median reported pre-mitigation result was 0.6 pCi/L. Of the 8 nearest counties with a figure, within 271 miles, the share of tests at or above 4 pCi/L runs from 0.0% to 14.3%.
Which counties border Webb County?
Webb County borders 7 counties: Duval County, La Salle County, Zapata County, Dimmit County, Jim Hogg County, McMullen County and Maverick County.
Products
Webb County, Products
Testing a home in Webb County
No CDC figure names Webb County; the nearest county with one, Nueces County (105 miles away), reported 0.0% 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 Webb County.
Test kits and monitors3
See every kit and monitor
Long-term kit
RL416 long-term radon test kit, lab fee included
- Lab fee included
Method: Alpha track
In home: 90 days to 12 months
MonitorAEGTEST
HOUND-1011 rechargeable radon detector with a screen
- C-NRPP 2024/25: Not included
- Battery
- Alarm
- Screen
Method: Semiconductor sensor
First reading: Within 6 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Webb County, Bordering counties
Counties bordering Webb County
Calculated by Radon411- Radon levels in Zapata CountyEPA zone 3
0.0%at or above 4 pCi/L
Median 0.1 pCi/L · 2 tests
- Radon levels in Maverick CountyEPA zone 3
0.0%at or above 4 pCi/L
Median 0.1 pCi/L · 2 tests
- Radon levels in Duval CountyEPA zone 3
No CDC figure for 2007 to 2016; its page reads it against its own neighbours.
- Radon levels in La Salle CountyEPA zone 3
No CDC figure for 2007 to 2016; its page reads it against its own neighbours.
- Radon levels in Dimmit CountyEPA zone 3
No CDC figure for 2007 to 2016; its page reads it against its own neighbours.
- Radon levels in Jim Hogg CountyEPA zone 3
No CDC figure for 2007 to 2016; its page reads it against its own neighbours.
- Radon levels in McMullen CountyEPA zone 3
No CDC figure for 2007 to 2016; its page reads it against its own neighbours.
Webb County, Cities and towns
Cities and towns in Webb County
Webb County is growing: the Census Bureau puts it at 281,224 residents on July 1, 2025, up 5.2% from 267,336 in 2020. That works out to 84 people per square mile of land. Laredo alone is home to 269,515 of them, 95.8% of the total. Together its 3 incorporated places hold 98.3% of those residents; the other 1.7% live outside any of them. Reported testing is thin here: 7 tests over 2005 to 2014, or under 0.1 for every 1,000 residents (2025 estimate), where Texas as a whole comes to 0.1.
From Laredo to El Cenizo, CDC publishes no figure by town: each reads Webb County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Laredo | 269,515 | +5.5% | 95.8% |
| Rio Bravo | 4,523 | −1.2% | 1.6% |
| El Cenizo | 2,457 | −2.8% | 0.9% |
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).
Webb County, Homes
Homes in Webb County
Of Webb County's 86,727 homes, 68% are detached houses, against 65% across Texas; 15% are in buildings of five or more homes. Half of its homes were built before 1996, close to Texas' 1990: 10% date from before 1960 and 42% from 2000 or later. 64% 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 | Webb County | Texas |
|---|---|---|
| Housing units | 86,727 | 11,890,808 |
| Detached houses | 68% | 65% |
| In buildings of 5 or more | 15% | 21% |
| Mobile homes | 9% | 7% |
| Built before 1960 | 10% | 13% |
| Built since 2000 | 42% | 37% |
| Middle year built | 1996 | 1990 |
| Owner-occupied | 64% | 63% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.