Short-term kitKidde
442020 short-term charcoal radon test kit
- Lab fee included
Method: Charcoal
In home: 3 days
Locations and reports
Radon Levels in Guadalupe County, Texas
EPA puts Guadalupe County in Zone 3, its lowest radon zone, and only 3 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
- Guadalupe
- 0.0%
- Texas
- 27.3%
Share of land USGS rates moderate or high potential
Tests reported
6
Too few for a share
- Guadalupe
- 6
- 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 Guadalupe 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
Guadalupe County, At a glance
Guadalupe 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 Guadalupe County, 2008 to 2017, laboratory
CDC holds 3 reported tests for Guadalupe 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). Guadalupe County beside the counties around it is how this page reads it.
What these figures count
Only 3 tests were reported to CDC for Guadalupe 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).
Guadalupe County, Compared
Guadalupe County radon figures, compared
Calculated by Radon411CDC's largest figure for Guadalupe County rests on 6 tests over the 2005 to 2014 laboratory totals, 0 of them at or above 4 pCi/L, so each test moves its share by 16.7 points and no rank or comparison is drawn from it. Results reached as high as 0.8 pCi/L, with a middle value of 0.4 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 (53 miles away) at 9.3%, Williamson County (76 miles away) at 2.0% and Bell County (104 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 Guadalupe 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.
Guadalupe County, Geology
The ground under Guadalupe County
PredictedUSGS's geologic map puts all of Guadalupe County's mapped land in one class: low radon potential. All of it lies in the area the map calls East Texas Province, to which USGS gives a radon index of 6, in the low band (5 to 8).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| East Texas Province | Cretaceous through Quaternary marine sandstone, shale, chalk, limestone, siltstone, clay, and lignite. | Low | 6 | 100% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Guadalupe County beside the ground around it
Across Texas 0.5% of the land is rated high; none of Guadalupe County's is. Of the 6 counties that border it, 1 has more moderate-potential ground, Hays County the most at 5.4%.
The map rates the ground, not the air in any home.
Local help
Guadalupe County, Local resources
Radon testing and mitigation in Guadalupe 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
Guadalupe County, Questions
Questions about radon in Guadalupe County
Are radon levels high in Guadalupe County?
Over the 2008 to 2017 laboratory totals, 0.0% of the radon tests reported to CDC for Guadalupe County, Texas were at or above 4 pCi/L, and the median reported pre-mitigation result was 0.6 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 Guadalupe County?
Guadalupe County borders 6 counties: Comal County, Caldwell County, Gonzales County, Wilson County, Bexar County and Hays County.
Products
Guadalupe County, Products
Testing a home in Guadalupe County
No CDC figure names Guadalupe 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 Guadalupe 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
RadonEye RD200 plug-in continuous radon monitor
- C-NRPP 2024/25: Approved
- Plug-in
- Bluetooth
- Alarm
- Screen, app
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
Guadalupe County, Bordering counties
Counties bordering Guadalupe County
Calculated by Radon411- Radon levels in Hays CountyEPA zone 3
14.8%at or above 4 pCi/L
Median 0.6 pCi/L · 27 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 Caldwell CountyEPA zone 3
0.0%at or above 4 pCi/L
Median 1.1 pCi/L · 2 tests
- 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 Wilson CountyEPA zone 3
0.0%at or above 4 pCi/L
Median 0.1 pCi/L · 1 test
Guadalupe County, Cities and towns
Cities and towns in Guadalupe County
Guadalupe County is growing: the Census Bureau puts it at 201,111 residents on July 1, 2025, up 15.8% from 173,722 in 2020. That works out to 283 people per square mile of land. New Braunfels, the largest place on its list (122,492 residents in all), extends beyond Guadalupe County, so no share of the total is worked out for it. Reported testing is thin here: 6 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 New Braunfels to Kingsbury, CDC publishes no figure by town: each reads Guadalupe County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| New Braunfelsextends beyond Guadalupe County | 122,492 | +33.7% | Counted whole |
| San Marcosextends beyond Guadalupe County | 77,830 | +14.1% | Counted whole |
| Schertzextends beyond Guadalupe County | 45,978 | +8.8% | Counted whole |
| Seguin | 41,048 | +39.2% | 20.4% |
| Ciboloextends beyond Guadalupe County | 39,019 | +18.9% | Counted whole |
| Selmaextends beyond Guadalupe County | 11,955 | +4.6% | Counted whole |
| Lulingextends beyond Guadalupe County | 5,920 | +5.7% | Counted whole |
| Marion | 1,101 | +5.2% | 0.5% |
| Santa Clara | 745 | +0.3% | 0.4% |
| New Berlin | 718 | +21.5% | 0.4% |
| Staples | 185 | −2.1% | Under 0.1% |
| Kingsbury | 143 | +5.1% | Under 0.1% |
12 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 Guadalupe County is counted whole, so it has no share.
Guadalupe County, Homes
Homes in Guadalupe County
Guadalupe County is a place of houses on their own lots: 79% of its 67,366 homes are detached single-family houses, against 65% across Texas. Much of Guadalupe County is recent building: 53% of its homes have gone up since 2000 and the middle year built is 2001, 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 | Guadalupe County | Texas |
|---|---|---|
| Housing units | 67,366 | 11,890,808 |
| Detached houses | 79% | 65% |
| In buildings of 5 or more | 5% | 21% |
| Mobile homes | 13% | 7% |
| Built before 1960 | 8% | 13% |
| Built since 2000 | 53% | 37% |
| Middle year built | 2001 | 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.