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 Karnes County, Texas
EPA puts Karnes County in Zone 3, its lowest radon zone. Homes with elevated levels occur in all three zones, so only a test measures yours.
Data checked By Radon411Methodology
Nearest county
6.6%
Bexar County, 55 miles
- Bexar
- 6.6%
- Texas
- 10.4%
Share at 4+ pCi/L, 197 tests, 2007 to 2016
Ground above low
None
27.3 pts below Texas
- Karnes
- 0.0%
- Texas
- 27.3%
Share of land USGS rates moderate or high potential
Tests reported
0
None published
A home here needs its own test
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 Karnes 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
Karnes County, At a glance
Karnes 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
No CDC test figures here
CDC has published no radon test figures for Karnes County. Bexar County, 55 miles away, is the nearest county with a figure over the 2007 to 2016 laboratory totals.
Karnes County, Compared
Karnes County radon figures, compared
Calculated by Radon411Karnes County has no radon test figure of its own from CDC, whose counts over the 2007 to 2016 laboratory totals name 140 other Texas counties and leave it out. Pooled across 140 Texas counties, 10.4% of reported tests reached that level; across every county in the country with a figure, 35.8%.
The nearest counties with a figure are Bexar County (55 miles away) at 6.6%, Nueces County (83 miles away) at 0.0% and Travis County (99 miles away) at 9.3%. 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 Karnes 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.
Karnes County, Geology
The ground under Karnes County
PredictedUSGS's geologic map puts all of Karnes County's mapped land in one class: low radon potential. The map puts 76.7% of Karnes County in the area it calls Coastal Plain and 23.3% in East Texas Province. USGS gives the first a radon index of 7 and the second 6, both in the low band (5 to 8).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Coastal Plain | Cretaceous through Quaternary marine sandstone, shale, chalk, limestone, siltstone, clay, and lignite. | Low | 7 | 76.7% |
| East Texas Province | Cretaceous through Quaternary marine sandstone, shale, chalk, limestone, siltstone, clay, and lignite. | Low | 6 | 23.3% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Karnes County beside the ground around it
Across Texas 0.5% of the land is rated high; none of Karnes 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
Karnes County, Local resources
Radon testing and mitigation in Karnes 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
Karnes County, Questions
Questions about radon in Karnes County
Are radon levels high in Karnes County?
No CDC testing statistics are published here for Karnes County, Texas yet. Of the 8 nearest counties with a figure, within 153 miles, the share of tests at or above 4 pCi/L runs from 0.0% to 14.3%.
Which counties border Karnes County?
Karnes County borders 7 counties: Wilson County, DeWitt County, Goliad County, Bee County, Atascosa County, Live Oak County and Gonzales County.
Products
Karnes County, Products
Testing a home in Karnes County
No CDC figure names Karnes County; the nearest county with one, Bexar County (55 miles away), reported 6.6% 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 Karnes 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
Monitor
EcoQube Wi-Fi continuous radon monitor
- C-NRPP 2024/25: Approved
- Plug-in
- Wi-Fi
- App only
Method: Ion chamber
First reading: Within 10 minutes
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Karnes County, Bordering counties
Counties bordering Karnes County
Calculated by Radon411- Radon levels in Wilson CountyEPA zone 3
0.0%at or above 4 pCi/L
Median 0.1 pCi/L · 1 test
- Radon levels in DeWitt CountyEPA zone 3
0.0%at or above 4 pCi/L
Median 1.3 pCi/L · 2 tests
- Radon levels in Goliad CountyEPA zone 3
0.0%at or above 4 pCi/L
Median 0.6 pCi/L · 6 tests
- Radon levels in Atascosa CountyEPA zone 3
0.0%at or above 4 pCi/L
Median 1.1 pCi/L · 1 test
- Radon levels in Gonzales CountyEPA zone 3
0.0%at or above 4 pCi/L
Median 0.1 pCi/L · 6 tests
- Radon levels in Bee CountyEPA zone 3
No CDC figure for 2007 to 2016; its page reads it against its own neighbours.
- Radon levels in Live Oak CountyEPA zone 3
No CDC figure for 2007 to 2016; its page reads it against its own neighbours.
Karnes County, Cities and towns
Cities and towns in Karnes County
The Census Bureau estimates 15,018 residents in Karnes County for July 1, 2025, 207 more than in 2020 (+1.4%). That works out to 20 people per square mile of land. Its largest town, Karnes City, has 3,540 residents, 23.6% of the total. Together its 4 incorporated places hold 55.1% of those residents; the other 44.9% live outside any of them. CDC publishes no radon test count for Karnes County; across Texas its counts for 2007 to 2016 come to 0.1 tests for every 1,000 residents (2025 estimate).
From Karnes City to Falls City, CDC publishes no figure by town: each reads Karnes County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Karnes City | 3,540 | −1.6% | 23.6% |
| Kenedy | 3,305 | −5.5% | 22.0% |
| Runge | 952 | +5.9% | 6.3% |
| Falls City | 476 | −4.6% | 3.2% |
4 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).
Karnes County, Homes
Homes in Karnes County
Of Karnes County's 5,892 homes, 67% are detached houses, against 65% across Texas; 17% are mobile homes. The homes are older than Texas' as a whole: half were built before 1982 (1990 for Texas), and 23% date from before 1960. 65% 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 | Karnes County | Texas |
|---|---|---|
| Housing units | 5,892 | 11,890,808 |
| Detached houses | 67% | 65% |
| In buildings of 5 or more | 5% | 21% |
| Mobile homes | 17% | 7% |
| Built before 1960 | 23% | 13% |
| Built since 2000 | 27% | 37% |
| Middle year built | 1982 | 1990 |
| Owner-occupied | 65% | 63% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.