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 Stephens County, Oklahoma
EPA puts Stephens County in Zone 3, its lowest radon zone, and only 2 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
Nearest county
8.9%
Oklahoma County, 78 miles
- Oklahoma
- 8.9%
- Oklahoma
- 12.6%
Share at 4+ pCi/L, 135 tests, 2006 to 2015
Ground above low
None
15.2 pts below Oklahoma
- Stephens
- 0.0%
- Oklahoma
- 15.2%
Share of land USGS rates moderate or high potential
Tests reported
4
Too few for a share
- Stephens
- 4
- 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 Stephens 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
Stephens County, At a glance
Stephens 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 Stephens County, 2008 to 2017, laboratory
CDC holds 2 reported tests for Stephens County over the 2008 to 2017 laboratory totals, with a median of 0.8 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Stephens County beside the counties around it is how this page reads it.
What these figures count
Only 2 tests were reported to CDC for Stephens 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).
Stephens County, Compared
Stephens County radon figures, compared
Calculated by Radon411CDC's largest figure for Stephens County rests on 4 tests over the 2005 to 2014 laboratory totals, 0 of them at or above 4 pCi/L, so each test moves its share by 25.0 points and no rank or comparison is drawn from it. Results reached as high as 0.8 pCi/L, with a middle value of 0.8 pCi/L.
The nearest counties with a figure are Oklahoma County (78 miles away) at 8.9%, Tulsa County (156 miles away) at 6.0% and Cherokee County (189 miles away) at 32.0%. Pooled across 53 Oklahoma counties, 12.6% of reported tests reached that level; across every county in the country with a figure, 36.3%.
Statewide for the same period, Delaware County reported the highest share (44.7%) and Tulsa County the lowest (6.0%). EPA's 1993 map puts Stephens 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.
Stephens County, Geology
The ground under Stephens County
PredictedUSGS's geologic map puts all of Stephens County's mapped land in one class: low radon potential. All of it lies in the area the map calls Central Oklahoma Plains and Hills, 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 |
|---|---|---|---|---|
| Central Oklahoma Plains and Hills | Nonmarine Permian and Tertiary rocks, including shale, sandstone, and conglomerate in the western part, and Mississippian and Pennsylvanian rocks in the eastern part. | 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.
Stephens County beside the ground around it
Across Oklahoma 0.6% of the land is rated high; none of Stephens 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
Stephens County, Local resources
Radon testing and mitigation in Stephens County
- Oklahoma's radon programDepartment of Environmental QualityOklahoma's radon program answers questions about testing, mitigation and the rules in Oklahoma.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsAsk the program whether it has free or discounted kits, or compare kits you can buy.
- Compare kits
- See the Oklahoma directoryNo professionals are listed in Oklahoma yet. The state program can point you to registered testers and mitigators.
What it means
Stephens County, Questions
Questions about radon in Stephens County
Are radon levels high in Stephens County?
Over the 2008 to 2017 laboratory totals, 0.0% of the radon tests reported to CDC for Stephens County, Oklahoma were at or above 4 pCi/L, and the median reported pre-mitigation result was 0.8 pCi/L. Of the 5 nearest counties with a figure, within 217 miles, the share of tests at or above 4 pCi/L runs from 6.0% to 44.7%.
Which counties border Stephens County?
Stephens County borders 6 counties: Jefferson County, Cotton County, Carter County, Garvin County, Comanche County and Grady County.
Products
Stephens County, Products
Testing a home in Stephens County
No CDC figure names Stephens County; the nearest county with one, Oklahoma County (78 miles away), reported 8.9% of its tests at or above 4 pCi/L over the 2006 to 2015 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 Stephens 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
MonitorINKBIRD
INK-RD3 battery radon monitor with an e-ink screen
- C-NRPP 2024/25: Not included
- Battery
- Screen
First reading: Within 24 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Stephens County, Bordering counties
Counties bordering Stephens County
Calculated by Radon411- Radon levels in Carter CountyEPA zone 3
25.0%at or above 4 pCi/L
Median 1.5 pCi/L · 8 tests
- Radon levels in Comanche CountyEPA zone 3
9.1%at or above 4 pCi/L
Median 0.6 pCi/L · 11 tests
- Radon levels in Jefferson CountyEPA zone 3
0.0%at or above 4 pCi/L
Median 0.1 pCi/L · 1 test
- Radon levels in Garvin CountyEPA zone 3
0.0%at or above 4 pCi/L
Median 1.9 pCi/L · 1 test
- Radon levels in Grady CountyEPA zone 3
0.0%at or above 4 pCi/L
Median 0.6 pCi/L · 2 tests
- Radon levels in Cotton CountyEPA zone 3
No CDC figure for 2006 to 2015; its page reads it against its own neighbours.
Stephens County, Cities and towns
Cities and towns in Stephens County
The Census Bureau estimates 44,310 residents in Stephens County for July 1, 2025, 1,475 more than in 2020 (+3.4%). That works out to 51 people per square mile of land. Duncan alone is home to 23,238 of them, 52.4% of the total. Together its 8 incorporated places hold 74.0% of those residents; the other 26.0% live outside any of them. Reported testing is thin here: 4 tests over 2005 to 2014, or 0.1 for every 1,000 residents (2025 estimate), where Oklahoma as a whole comes to 0.2.
From Duncan to Loco, CDC publishes no figure by town: each reads Stephens County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Duncan | 23,238 | +2.7% | 52.4% |
| Marlow | 4,514 | +3.2% | 10.2% |
| Comanche | 1,393 | +2.2% | 3.1% |
| Central High | 1,229 | +4.9% | 2.8% |
| Bray | 988 | +4.9% | 2.2% |
| Empire City | 741 | +5.0% | 1.7% |
| Velma | 570 | +3.4% | 1.3% |
| Loco | 110 | +4.8% | 0.2% |
8 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).
Stephens County, Homes
Homes in Stephens County
Stephens County is a place of houses on their own lots: 82% of its 20,311 homes are detached single-family houses, against 73% across Oklahoma. Half of its homes were built before 1975, close to Oklahoma's 1980: 27% date from before 1960 and 14% from 2000 or later. 74% of occupied homes are lived in by their owner (Oklahoma: 66%); in the rest a tenant can run a test, but a fix is the landlord's to make.
| Homes | Stephens County | Oklahoma |
|---|---|---|
| Housing units | 20,311 | 1,763,036 |
| Detached houses | 82% | 73% |
| In buildings of 5 or more | 4% | 12% |
| Mobile homes | 8% | 9% |
| Built before 1960 | 27% | 21% |
| Built since 2000 | 14% | 25% |
| Middle year built | 1975 | 1980 |
| Owner-occupied | 74% | 66% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.