Short-term kit
Radon Short Term Test Kit short-term charcoal radon test kit, lab fee included
- Lab fee included
Method: Charcoal
In home: 2 to 7 days
Locations and reports
Radon Levels in Kendall County, Texas
EPA puts Kendall County in Zone 3, its lowest radon zone, and only 7 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
Highest bordering
6.6%
Bexar County
- Bexar
- 6.6%
1 of 6 neighbours have 30+ tests, 2007 to 2016
Nearest county
6.6%
Bexar County, 36 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
- Kendall
- 0.0%
- Texas
- 27.3%
Share of land USGS rates moderate or high potential
Tests reported
7
Too few for a share
- Kendall
- 7
- Needed
- 30
2008 to 2017, 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 Kendall 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
Kendall County, At a glance
Kendall 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 Kendall County, 2008 to 2017, laboratory
CDC holds 7 reported tests for Kendall County over the 2008 to 2017 laboratory totals, with a median of 5.7 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Kendall County beside the counties around it is how this page reads it.
What these figures count
Only 7 tests were reported to CDC for Kendall 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).
Kendall County, Compared
Kendall County radon figures, compared
Calculated by Radon411CDC's largest figure for Kendall County rests on 7 tests over the 2008 to 2017 laboratory totals, 5 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 15.9 pCi/L, with a middle value of 5.7 pCi/L.
Bexar County, the one bordering county with a figure over the 2007 to 2016 laboratory totals, reported 6.6% of its tests at or above 4 pCi/L. Farther out, Travis County (62 miles away) at 9.3%, Williamson County (82 miles away) at 2.0% and Bell County (105 miles away) at 14.3% have figures too. 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 Kendall 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.
Kendall County, Geology
The ground under Kendall County
PredictedUSGS's geologic map puts all of Kendall County's mapped land in one class: low radon potential. All of it lies in the area the map calls Southern High Plains and Plateaus, 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 |
|---|---|---|---|---|
| Southern High Plains and Plateaus | Paleozoic and Mesozoic sandstone, limestone, shale. | 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.
Kendall County beside the ground around it
Across Texas 0.5% of the land is rated high; none of Kendall County's is. Of the 6 counties that border it, 2 have more moderate-potential ground, Blanco County the most at 35.3%.
The map rates the ground, not the air in any home.
Local help
Kendall County, Local resources
Radon testing and mitigation in Kendall 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
Kendall County, Questions
Questions about radon in Kendall County
Are radon levels high in Kendall County?
Over the 2008 to 2017 laboratory totals, 71.4% of the radon tests reported to CDC for Kendall County, Texas were at or above 4 pCi/L, and the median reported pre-mitigation result was 5.7 pCi/L. Bexar County, the one bordering county with a figure over the 2007 to 2016 laboratory totals, reported 6.6% of its tests at or above 4 pCi/L.
Which counties border Kendall County?
Kendall County borders 6 counties: Comal County, Bandera County, Blanco County, Kerr County, Bexar County and Gillespie County.
Products
Kendall County, Products
Testing a home in Kendall County
No CDC figure names Kendall County; the nearest county with one, Bexar County (36 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 Kendall County.
Test kits and monitors3
See every kit and monitor
Long-term kit
RL116 long-term radon test kit
- Lab fee extra
Method: Alpha track
In home: 90 days to 12 months
Monitor
Corentium Home battery digital radon detector
- C-NRPP 2024/25: Approved
- Battery
- Screen
Method: Alpha spectrometry
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Kendall County, Bordering counties
Counties bordering Kendall County
Calculated by Radon411- Radon levels in Gillespie CountyEPA zone 3
20.0%at or above 4 pCi/L
Median 0.8 pCi/L · 10 tests
- Radon levels in Kerr CountyEPA zone 3
12.5%at or above 4 pCi/L
Median 1.1 pCi/L · 16 tests
- Radon levels in Bexar CountyEPA zone 3
6.6%at or above 4 pCi/L
Median 0.6 pCi/L · 197 tests
- Radon levels in Comal CountyEPA zone 3
4.5%at or above 4 pCi/L
Median 0.9 pCi/L · 22 tests
- Radon levels in Blanco CountyEPA zone 3
0.0%at or above 4 pCi/L
Median 0.2 pCi/L · 2 tests
- Radon levels in Bandera CountyEPA zone 3
No CDC figure for 2007 to 2016; its page reads it against its own neighbours.
Kendall County, Cities and towns
Cities and towns in Kendall County
Kendall County is growing: the Census Bureau puts it at 53,289 residents on July 1, 2025, up 19.6% from 44,568 in 2020. That works out to 80 people per square mile of land. Its largest town, Boerne, has 24,047 residents, 45.1% of the total. CDC's 7 reported tests for 2008 to 2017 work out to 0.1 per 1,000 residents (2025 estimate), close to Texas' 0.1.
From Boerne to Fair Oaks Ranch, CDC publishes no figure by town: each reads Kendall County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Boerne | 24,047 | +33.0% | 45.1% |
| Fair Oaks Ranchextends beyond Kendall County | 12,025 | +21.0% | Counted whole |
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). A place that extends beyond Kendall County is counted whole, so it has no share.
Kendall County, Homes
Homes in Kendall County
Kendall County is a place of houses on their own lots: 80% of its 18,797 homes are detached single-family houses, against 65% across Texas. Much of Kendall County is recent building: 55% of its homes have gone up since 2000 and the middle year built is 2002, against 1990 for Texas. Owners live in 78% of the occupied homes (Texas: 63%), so for most households a test and a fix are their own to order.
| Homes | Kendall County | Texas |
|---|---|---|
| Housing units | 18,797 | 11,890,808 |
| Detached houses | 80% | 65% |
| In buildings of 5 or more | 9% | 21% |
| Mobile homes | 6% | 7% |
| Built before 1960 | 6% | 13% |
| Built since 2000 | 55% | 37% |
| Middle year built | 2002 | 1990 |
| Owner-occupied | 78% | 63% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.