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 Harmon County, Oklahoma
EPA puts Harmon 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
8.9%
Oklahoma County, 149 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
- Harmon
- 0.0%
- Oklahoma
- 15.2%
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 Harmon 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
Harmon County, At a glance
Harmon 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 Harmon County. Oklahoma County, 149 miles away, is the nearest county with a figure over the 2006 to 2015 laboratory totals.
Harmon County, Compared
Harmon County radon figures, compared
Calculated by Radon411Harmon County has no radon test figure of its own from CDC, whose counts over the 2006 to 2015 laboratory totals name 53 other Oklahoma counties and leave it out. Pooled across 53 Oklahoma counties, 12.6% of reported tests reached that level; across every county in the country with a figure, 36.3%.
The nearest counties with a figure are Oklahoma County (149 miles away) at 8.9%, Tulsa County (240 miles away) at 6.0% and Washington County (260 miles away) at 11.3%. 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 Harmon 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.
Harmon County, Geology
The ground under Harmon County
PredictedUSGS's geologic map puts all of Harmon 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 | 99.8% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Harmon County beside the ground around it
Across Oklahoma 0.6% of the land is rated high; none of Harmon County's is. Of the 6 counties that border it, 2 have more moderate-potential ground, Collingsworth County, TX the most at 1.3%.
The map rates the ground, not the air in any home.
Local help
Harmon County, Local resources
Radon testing and mitigation in Harmon 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
Harmon County, Questions
Questions about radon in Harmon County
Are radon levels high in Harmon County?
No CDC testing statistics are published here for Harmon County, Oklahoma yet. Of the 5 nearest counties with a figure, within 306 miles, the share of tests at or above 4 pCi/L runs from 6.0% to 44.7%.
Which counties border Harmon County?
Harmon County borders 6 counties: Greer County, OK, Collingsworth County, TX, Jackson County, OK, Childress County, TX, Hardeman County, TX and Beckham County, OK.
Products
Harmon County, Products
Testing a home in Harmon County
No CDC figure names Harmon County; the nearest county with one, Oklahoma County (149 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 Harmon 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
Hello Radon C battery radon monitor with an e-ink screen
- C-NRPP 2024/25: Not included
- Battery
- Screen
Method: Alpha spectrometry
First reading: Within 24 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Harmon County, Bordering counties
Counties bordering Harmon County
Calculated by Radon411- Radon levels in Collingsworth County, TXEPA zone 3
100.0%at or above 4 pCi/L
Median 12.6 pCi/L · 1 test
- Radon levels in Jackson County, OKEPA zone 3
0.0%at or above 4 pCi/L
Median 0.1 pCi/L · 3 tests
- Radon levels in Childress County, TXEPA zone 3
0.0%at or above 4 pCi/L
Median 1.1 pCi/L · 1 test
- Radon levels in Beckham County, OKEPA zone 3
0.0%at or above 4 pCi/L
Median 1.5 pCi/L · 5 tests
- Radon levels in Greer County, OKEPA zone 3
No CDC figure for 2006 to 2015; its page reads it against its own neighbours.
- Radon levels in Hardeman County, TXEPA zone 3
No CDC figure for 2006 to 2015; its page reads it against its own neighbours.
Harmon County, Cities and towns
Cities and towns in Harmon County
Harmon County has been losing residents: from 2,476 in 2020 to 2,327 on July 1, 2025, a fall of 6.0% by the Census Bureau's estimates. Spread over its land, that is 4.3 people to the square mile. Hollis alone is home to 1,673 of them, 71.9% of the total. Together its 2 incorporated places hold 76.0% of those residents; the other 24.0% live outside any of them. CDC publishes no radon test count for Harmon County; across Oklahoma its counts for 2006 to 2015 come to 0.2 tests for every 1,000 residents (2025 estimate).
From Hollis to Gould, CDC publishes no figure by town: each reads Harmon County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Hollis | 1,673 | −6.2% | 71.9% |
| Gould | 95 | −5.9% | 4.1% |
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).
Harmon County, Homes
Homes in Harmon County
Harmon County is a place of houses on their own lots: 87% of its 1,358 homes are detached single-family houses, against 73% across Oklahoma. The homes are older than Oklahoma's as a whole: half were built before 1965 (1980 for Oklahoma), and 40% date from before 1960. 72% 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 | Harmon County | Oklahoma |
|---|---|---|
| Housing units | 1,358 | 1,763,036 |
| Detached houses | 87% | 73% |
| In buildings of 5 or more | 3% | 12% |
| Mobile homes | 6% | 9% |
| Built before 1960 | 40% | 21% |
| Built since 2000 | 7% | 25% |
| Middle year built | 1965 | 1980 |
| Owner-occupied | 72% | 66% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.