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
Locations and reports
Radon Levels in Garfield County, Montana
EPA puts Garfield County in Zone 1, its highest radon zone. Homes with elevated levels occur in all three zones, so only a test measures yours.
Data checked By Radon411Methodology
Highest bordering
50.0%
Valley County
- Valley
- 50.0%
1 of 7 neighbours have 30+ tests, 2006 to 2015
Nearest county
50.0%
Valley County, 77 miles
- Valley
- 50.0%
- Montana
- 47.4%
Share at 4+ pCi/L, 40 tests, 2006 to 2015
Ground above low
100.0%
Level with Montana
- Garfield
- 100.0%
- Montana
- 100.0%
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 1
Highest potential
- Zone 1
- 2
- 3
1 highest, 3 lowest
EPA predicts over 4 pCi/L indoors
Read a result for Garfield 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
Garfield County, At a glance
Garfield County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Garfield County in
USGS geologic potential: High across 69% 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 Garfield County. Valley County, the one bordering county with a figure over the 2006 to 2015 laboratory totals, reported 50.0% of its tests at or above 4 pCi/L.
Garfield County, Compared
Garfield County radon figures, compared
Calculated by Radon411CDC's county radon counts over the 2006 to 2015 laboratory totals cover 52 Montana counties, and Garfield County is not among them: no year's figure and no ten-year laboratory total names it. Pooled across 52 Montana counties, 47.4% of reported tests reached that level; across every county in the country with a figure, 36.3%.
Valley County, the one bordering county with a figure over the 2006 to 2015 laboratory totals, reported 50.0% of its tests at or above 4 pCi/L. Farther out, Dawson County (98 miles away) at 47.3%, Fergus County (105 miles away) at 72.2% and Yellowstone County (111 miles away) at 43.1% have figures too. Statewide for the same period, Sheridan County reported the highest share (75.7%) and Hill County the lowest (35.0%).
EPA's 1993 map puts Garfield County in Zone 1, the map's highest label: a predicted county average above 4 pCi/L. USGS geology rates 69% of the county's land high radon potential.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Garfield County, Geology
The ground under Garfield County
PredictedUSGS's geologic map splits Garfield County: 68.8% of its land is high radon potential and 31.2% moderate. The map puts 52.7% of Garfield County in the area it calls Great Plains and 31.2% in Plains and Mountains, with one smaller area beside them. USGS gives the first a radon index of 12, in the high band (12 to 17), and the second 10, in the moderate band (9 to 11).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Great Plains | Tertiary sandstone, siltstone, shale, coal. | High | 12 | 52.7% |
| Plains and Mountains | Marine and continental shale, siltstone, and sandstone of Cretaceous and Tertiary ages, and volcanic rocks. | Moderate | 10 | 31.2% |
| Great Plains (Glaciated) | Glacial deposits derived from Cretaceous shales containing higher than average amounts of uranium. | High | 13 | 16.1% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Garfield County beside the ground around it
On high-potential ground Garfield County is close to Montana as a whole: 68.8% of its land against 78.5%. Of the 7 counties that border it, 5 have more high-potential ground, Valley County the most at 100%.
The map rates the ground, not the air in any home.
Local help
Garfield County, Local resources
Radon testing and mitigation in Garfield County
- Radon Control ProgramRadon Control Program, run by Montana DEQ, does not license radon professionals and offers free or discounted test kits, and answers questions about testing and mitigation in Montana.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsThe program says:
Energy Bureau staff manage the radon information toll-free hotline and distribute subsidized radon test kits to Montana residents.
- Compare kits
- See the Montana directoryNo professionals are listed in Montana yet. The state program can point you to registered testers and mitigators.
What Montana's program says
- Phone
- 1-800-546-0483
- Licensing of radon professionals
Montana DEQ does not certify or require proof of certification for the contractors listed.
What it means
Garfield County, Questions
Questions about radon in Garfield County
Are radon levels high in Garfield County?
No CDC testing statistics are published here for Garfield County, Montana yet. Valley County, the one bordering county with a figure over the 2006 to 2015 laboratory totals, reported 50.0% of its tests at or above 4 pCi/L.
Which counties border Garfield County?
Garfield County borders 7 counties: Petroleum County, McCone County, Phillips County, Valley County, Prairie County, Rosebud County and Custer County.
Products
Garfield County, Products
Testing a home in Garfield County
No CDC figure names Garfield County; the nearest county with one, Valley County (77 miles away), reported 50.0% 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. In Zone 1 the year-round level in Garfield County is the one to know: a long-term test (more than 90 days) or a monitor, with a short-term kit for a first answer.
Test kits and monitors3
See every kit and monitor
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
Short-term kitFirst Alert
RD1 short-term charcoal radon test kit
- Lab fee included
Method: Charcoal
In home: 2 to 4 days
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Garfield County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Garfield County
Explore
Garfield County, Bordering counties
Counties bordering Garfield County
Calculated by Radon411- Radon levels in Phillips CountyEPA zone 1
100.0%at or above 4 pCi/L
Median 6.2 pCi/L · 2 tests
- Radon levels in Valley CountyEPA zone 1
50.0%at or above 4 pCi/L
Median 4.2 pCi/L · 40 tests
- Radon levels in Rosebud CountyEPA zone 1
50.0%at or above 4 pCi/L
Median 4.4 pCi/L · 6 tests
- Radon levels in Custer CountyEPA zone 1
37.9%at or above 4 pCi/L
Median 3.4 pCi/L · 29 tests
- Radon levels in Prairie CountyEPA zone 1
28.6%at or above 4 pCi/L
Median 3.3 pCi/L · 7 tests
- Radon levels in McCone CountyEPA zone 1
25.0%at or above 4 pCi/L
Median 2.5 pCi/L · 4 tests
- Radon levels in Petroleum CountyEPA zone 2
No CDC figure for 2006 to 2015; its page reads it against its own neighbours.
Garfield County, Cities and towns
Cities and towns in Garfield County
About 1,148 people live in Garfield County by the Census Bureau's estimate for July 1, 2025, 22 fewer than in 2020 (−1.9%). Spread over its land, that is 0.2 people to the square mile. Jordan, its one incorporated place, has 348 residents, 30.3% of the total. CDC publishes no radon test count for Garfield County; across Montana its counts for 2006 to 2015 come to 7.5 tests for every 1,000 residents (2025 estimate).
Jordan is the one incorporated place here; CDC publishes no figure by town, so it reads Garfield County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Jordan | 348 | −1.4% | 30.3% |
One incorporated place, 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).
Garfield County, Homes
Homes in Garfield County
Garfield County is a place of houses on their own lots: 76% of its 746 homes are detached single-family houses, against 69% across Montana. Half of its homes were built before 1976, close to Montana's 1980: 32% date from before 1960 and 23% from 2000 or later. 70% of occupied homes are lived in by their owner (Montana: 69%); in the rest a tenant can run a test, but a fix is the landlord's to make.
| Homes | Garfield County | Montana |
|---|---|---|
| Housing units | 746 | 522,939 |
| Detached houses | 76% | 69% |
| In buildings of 5 or more | 0% | 9% |
| Mobile homes | 19% | 10% |
| Built before 1960 | 32% | 26% |
| Built since 2000 | 23% | 27% |
| Middle year built | 1976 | 1980 |
| Owner-occupied | 70% | 69% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.