Short-term kit
RA400 short-term liquid scintillation radon test kit, lab fee included
- Lab fee included
Method: Liquid scintillation
In home: 48 to 96 hours
Locations and reports
Radon Levels in Frio County, Texas
EPA puts Frio 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, 54 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
- Frio
- 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 Frio 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
Frio County, At a glance
Frio 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 Frio County. Bexar County, 54 miles away, is the nearest county with a figure over the 2007 to 2016 laboratory totals.
Frio County, Compared
Frio County radon figures, compared
Calculated by Radon411No CDC figure names Frio County, in any year or ten-year total; over the 2007 to 2016 laboratory totals, the agency's counts reach 140 Texas counties without it. 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 (54 miles away) at 6.6%, Nueces County (120 miles away) at 0.0% and Travis County (129 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 Frio 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.
Frio County, Geology
The ground under Frio County
PredictedUSGS's geologic map puts all of Frio 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 | 100% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Frio County beside the ground around it
Across Texas 0.5% of the land is rated high; none of Frio County's is. None of the 6 counties that border it has any moderate-potential ground either.
The map rates the ground, not the air in any home.
Local help
Frio County, Local resources
Radon testing and mitigation in Frio 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
Frio County, Questions
Questions about radon in Frio County
Are radon levels high in Frio County?
No CDC testing statistics are published here for Frio County, Texas yet. Of the 8 nearest counties with a figure, within 217 miles, the share of tests at or above 4 pCi/L runs from 0.0% to 17.1%.
Which counties border Frio County?
Frio County borders 6 counties: La Salle County, Atascosa County, Medina County, Zavala County, Dimmit County and Uvalde County.
Products
Frio County, Products
Testing a home in Frio County
No CDC figure names Frio County; the nearest county with one, Bexar County (54 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 Frio 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-3786 rechargeable radon monitor with a 3.5-inch color screen
- C-NRPP 2024/25: Not included
- Battery
- Alarm
- Screen
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
Frio County, Bordering counties
Counties bordering Frio County
Calculated by Radon411- 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 Medina CountyEPA zone 3
0.0%at or above 4 pCi/L
Median 0.5 pCi/L · 2 tests
- 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 Zavala 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 Uvalde CountyEPA zone 3
No CDC figure for 2007 to 2016; its page reads it against its own neighbours.
Frio County, Cities and towns
Cities and towns in Frio County
The Census Bureau estimates 18,823 residents in Frio County for July 1, 2025, 417 more than in 2020 (+2.3%). That works out to 17 people per square mile of land. Its largest town, Pearsall, has 9,170 residents, 48.7% of the total. Together its 2 incorporated places hold 69.0% of those residents; the other 31.0% live outside any of them. CDC publishes no radon test count for Frio County; across Texas its counts for 2007 to 2016 come to 0.1 tests for every 1,000 residents (2025 estimate).
From Pearsall to Dilley, CDC publishes no figure by town: each reads Frio County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Pearsall | 9,170 | +4.4% | 48.7% |
| Dilley | 3,809 | +4.3% | 20.2% |
2 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).
Frio County, Homes
Homes in Frio County
Of Frio County's 6,378 homes, 65% are detached houses, against 65% across Texas; 19% are mobile homes. Half of its homes were built before 1984, close to Texas' 1990: 15% date from before 1960 and 27% from 2000 or later. 63% 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 | Frio County | Texas |
|---|---|---|
| Housing units | 6,378 | 11,890,808 |
| Detached houses | 65% | 65% |
| In buildings of 5 or more | 5% | 21% |
| Mobile homes | 19% | 7% |
| Built before 1960 | 15% | 13% |
| Built since 2000 | 27% | 37% |
| Middle year built | 1984 | 1990 |
| Owner-occupied | 63% | 63% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.