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 Castro County, Texas
EPA puts Castro County in Zone 2, its middle radon zone, and only 1 radon test from it is 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
71.4%
Randall County
- Randall
- 71.4%
1 of 6 neighbours have 30+ tests, 2007 to 2016
Nearest county
71.4%
Randall County, 37 miles
- Randall
- 71.4%
- Texas
- 10.4%
Share at 4+ pCi/L, 84 tests, 2007 to 2016
Ground above low
100.0%
72.7 pts above Texas
- Castro
- 100.0%
- Texas
- 27.3%
Share of land USGS rates moderate or high potential
Tests reported
1
Too few for a share
- Castro
- 1
- Needed
- 30
2008 to 2017, laboratory
EPA radon zone
Zone 2
Moderate potential
- 1
- Zone 2
- 3
1 highest, 3 lowest
EPA predicts 2 to 4 pCi/L indoors
Read a result for Castro 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
Castro County, At a glance
Castro County at a glance
Predicted: EPA radon zone
EPA Zone 2: moderate predicted potential
Castro County is a
USGS geologic potential: Moderate across 100% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Castro County, 2008 to 2017, laboratory
CDC holds 1 reported test for Castro County over the 2008 to 2017 laboratory totals, a result of 3.6 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Castro County beside the counties around it is how this page reads it.
What these figures count
Only 1 test was reported to CDC for Castro 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).
Castro County, Compared
Castro County radon figures, compared
Calculated by Radon411CDC's largest figure for Castro County rests on 1 test over the 2008 to 2017 laboratory totals, 0 of them at or above 4 pCi/L, so each test moves its share by 100.0 points and no rank or comparison is drawn from it. Results reached as high as 3.6 pCi/L, with a middle value of 3.6 pCi/L.
Randall County, the one bordering county with a figure over the 2007 to 2016 laboratory totals, reported 71.4% of its tests at or above 4 pCi/L. Farther out, Potter County (64 miles away) at 20.0%, Lubbock County (68 miles away) at 57.8% and Midland County (184 miles away) at 1.0% 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 Castro County in Zone 2, its middle label: a predicted county average between 2 and 4 pCi/L. USGS geology rates 100% of the county's land moderate radon potential.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Castro County, Geology
The ground under Castro County
PredictedUSGS's geologic map puts all of Castro County's mapped land in one class: moderate radon potential. All of it lies in the area the map calls Northern High Plains and Plateaus, to which USGS gives a radon index of 10, in the moderate band (9 to 11).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Northern High Plains and Plateaus | Tertiary sandstone, siltstone, shale. | Moderate | 10 | 100% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Castro County beside the ground around it
Across Texas 0.5% of the land is rated high; none of Castro County's is. Of the 6 counties that border it, none has as large a share of moderate-potential ground; Hale County comes nearest at 100%.
The map rates the ground, not the air in any home.
Local help
Castro County, Local resources
Radon testing and mitigation in Castro 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
Castro County, Questions
Questions about radon in Castro County
Are radon levels high in Castro County?
Over the 2008 to 2017 laboratory totals, 0.0% of the radon tests reported to CDC for Castro County, Texas were at or above 4 pCi/L, and the median reported pre-mitigation result was 3.6 pCi/L. Randall County, the one bordering county with a figure over the 2007 to 2016 laboratory totals, reported 71.4% of its tests at or above 4 pCi/L.
Which counties border Castro County?
Castro County borders 6 counties: Parmer County, Swisher County, Lamb County, Randall County, Hale County and Deaf Smith County.
Products
Castro County, Products
Testing a home in Castro County
No CDC figure names Castro County; the nearest county with one, Randall County (37 miles away), reported 71.4% 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. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Castro County; a long-term test tells the year-round average.
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
Corentium Home 2 battery digital radon monitor
- C-NRPP 2024/25: Not included
- Battery
- Bluetooth
- Screen, app
Method: Alpha spectrometry
Readings: Every 60 minutes
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Castro County, Bordering counties
Counties bordering Castro County
Calculated by Radon411- Radon levels in Parmer CountyEPA zone 2
100.0%at or above 4 pCi/L
Median 10.6 pCi/L · 1 test
- Radon levels in Swisher CountyEPA zone 2
100.0%at or above 4 pCi/L
Median 7.8 pCi/L · 6 tests
- Radon levels in Hale CountyEPA zone 2
83.3%at or above 4 pCi/L
Median 7.8 pCi/L · 12 tests
- Radon levels in Deaf Smith CountyEPA zone 2
75.0%at or above 4 pCi/L
Median 10.9 pCi/L · 4 tests
- Radon levels in Randall CountyEPA zone 2
71.4%at or above 4 pCi/L
Median 6.2 pCi/L · 84 tests
- Radon levels in Lamb CountyEPA zone 2
No CDC figure for 2007 to 2016; its page reads it against its own neighbours.
Castro County, Cities and towns
Cities and towns in Castro County
Castro County's population has barely moved since 2020: 7,295 residents on July 1, 2025 against 7,324 then, by the Census Bureau's estimates. Spread over its land, that is 8.2 people to the square mile. Dimmitt alone is home to 4,069 of them, 55.8% of the total. Together its 3 incorporated places hold 71.8% of those residents; the other 28.2% live outside any of them. CDC's 1 reported test for 2008 to 2017 work out to 0.1 per 1,000 residents (2025 estimate), close to Texas' 0.1.
From Dimmitt to Nazareth, CDC publishes no figure by town: each reads Castro County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Dimmitt | 4,069 | −1.2% | 55.8% |
| Hart | 865 | +0.1% | 11.9% |
| Nazareth | 307 | +0.3% | 4.2% |
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).
Castro County, Homes
Homes in Castro County
Castro County is a place of houses on their own lots: 77% of its 3,026 homes are detached single-family houses, against 65% across Texas. The homes are older than Texas' as a whole: half were built before 1966 (1990 for Texas), and 37% date from before 1960. 69% 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 | Castro County | Texas |
|---|---|---|
| Housing units | 3,026 | 11,890,808 |
| Detached houses | 77% | 65% |
| In buildings of 5 or more | 5% | 21% |
| Mobile homes | 14% | 7% |
| Built before 1960 | 37% | 13% |
| Built since 2000 | 10% | 37% |
| Middle year built | 1966 | 1990 |
| Owner-occupied | 69% | 63% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.