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 Rosebud County, Montana
EPA puts Rosebud County in Zone 1, its highest radon zone, and only 5 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
43.1%
Yellowstone County
- Yellowstone
- 43.1%
1 of 8 neighbours have 30+ tests, 2006 to 2015
Nearest county
43.1%
Yellowstone County, 77 miles
- Yellowstone
- 43.1%
- Montana
- 47.4%
Share at 4+ pCi/L, 1,421 tests, 2006 to 2015
Ground above low
100.0%
Level with Montana
- Rosebud
- 100.0%
- Montana
- 100.0%
Share of land USGS rates moderate or high potential
Tests reported
9
Too few for a share
- Rosebud
- 9
- Needed
- 30
2005 to 2014, laboratory
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 Rosebud 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
Rosebud County, At a glance
Rosebud County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Rosebud County in
USGS geologic potential: High across 56% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Rosebud County, 2008 to 2017, laboratory
CDC holds 5 reported tests for Rosebud County over the 2008 to 2017 laboratory totals, with a median of 2.9 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Rosebud County beside the counties around it is how this page reads it.
What these figures count
Only 5 tests were reported to CDC for Rosebud 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).
Rosebud County, Compared
Rosebud County radon figures, compared
Calculated by Radon411CDC's largest figure for Rosebud County rests on 9 tests over the 2005 to 2014 laboratory totals, 5 of them at or above 4 pCi/L, so each test moves its share by 11.1 points and no rank or comparison is drawn from it. Results reached as high as 8.6 pCi/L, with a middle value of 5.9 pCi/L.
Yellowstone County, the one bordering county with a figure over the 2006 to 2015 laboratory totals, reported 43.1% of its tests at or above 4 pCi/L. Farther out, Dawson County (113 miles away) at 47.3%, Carbon County (131 miles away) at 52.5% and Stillwater County (134 miles away) at 61.8% have figures too. Pooled across 52 Montana counties, 47.4% of reported tests reached that level; across every county in the country with a figure, 36.3%.
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 Rosebud County in Zone 1, the map's highest label: a predicted county average above 4 pCi/L. USGS geology rates 56% of the county's land high radon potential.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Rosebud County, Geology
The ground under Rosebud County
PredictedUSGS's geologic map splits Rosebud County: 56.2% of its land is high radon potential and 43.8% moderate. The map puts 56.2% of Rosebud County in the area it calls Great Plains and 43.8% in Plains and Mountains. 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 | 56.2% |
| Plains and Mountains | Marine and continental shale, siltstone, and sandstone of Cretaceous and Tertiary ages, and volcanic rocks. | Moderate | 10 | 43.8% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Rosebud County beside the ground around it
Montana as a whole has more high-potential ground than Rosebud County: 78.5% of its land, against 56.2% here. Of the 8 counties that border it, 3 have more high-potential ground, Custer County the most at 95.0%.
The map rates the ground, not the air in any home.
Local help
Rosebud County, Local resources
Radon testing and mitigation in Rosebud 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
Rosebud County, Questions
Questions about radon in Rosebud County
Are radon levels high in Rosebud County?
Over the 2008 to 2017 laboratory totals, 40.0% of the radon tests reported to CDC for Rosebud County, Montana were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.9 pCi/L. Yellowstone County, the one bordering county with a figure over the 2006 to 2015 laboratory totals, reported 43.1% of its tests at or above 4 pCi/L.
Which counties border Rosebud County?
Rosebud County borders 8 counties: Treasure County, Big Horn County, Powder River County, Custer County, Yellowstone County, Musselshell County, Garfield County and Petroleum County.
Products
Rosebud County, Products
Testing a home in Rosebud County
No CDC figure names Rosebud County; the nearest county with one, Yellowstone County (77 miles away), reported 43.1% 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 Rosebud 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 monitorMonitorSafetySiren
Pro4 plug-in radon detector with a display and alarm
- C-NRPP 2024/25: Not included
- Plug-in
- Alarm
- Screen
First reading: Within 48 hours
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
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Rosebud County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Rosebud County
Explore
Rosebud County, Bordering counties
Counties bordering Rosebud County
Calculated by Radon411- Radon levels in Powder River CountyEPA zone 1
71.4%at or above 4 pCi/L
Median 4.5 pCi/L · 7 tests
- Radon levels in Yellowstone CountyEPA zone 2
43.1%at or above 4 pCi/L
Median 3.5 pCi/L · 1,421 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 Musselshell CountyEPA zone 2
28.6%at or above 4 pCi/L
Median 2.7 pCi/L · 14 tests
- Radon levels in Big Horn CountyEPA zone 1
25.0%at or above 4 pCi/L
Median 1.9 pCi/L · 20 tests
- Radon levels in Treasure CountyEPA zone 2
No CDC figure for 2006 to 2015; its page reads it against its own neighbours.
- Radon levels in Garfield CountyEPA zone 1
No CDC figure for 2006 to 2015; its page reads it against its own neighbours.
- Radon levels in Petroleum CountyEPA zone 2
No CDC figure for 2006 to 2015; its page reads it against its own neighbours.
Rosebud County, Cities and towns
Cities and towns in Rosebud County
About 8,253 people live in Rosebud County by the Census Bureau's estimate for July 1, 2025, 56 fewer than in 2020 (−0.7%). Spread over its land, that is 1.6 people to the square mile. Its largest town, Colstrip, has 2,091 residents, 25.3% of the total. Together its 2 incorporated places hold 45.4% of those residents; the other 54.6% live outside any of them. Reported testing is thin here: 9 tests over 2005 to 2014, or 1.1 for every 1,000 residents (2025 estimate), where Montana as a whole comes to 6.7.
From Colstrip to Forsyth, CDC publishes no figure by town: each reads Rosebud County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Colstrip | 2,091 | −0.2% | 25.3% |
| Forsyth | 1,652 | −1.2% | 20.0% |
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).
Rosebud County, Homes
Homes in Rosebud County
Of Rosebud County's 3,785 homes, 66% are detached houses, against 69% across Montana; 18% are mobile homes. Half of its homes were built before 1979, close to Montana's 1980: 21% date from before 1960 and 11% from 2000 or later. 66% 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 | Rosebud County | Montana |
|---|---|---|
| Housing units | 3,785 | 522,939 |
| Detached houses | 66% | 69% |
| In buildings of 5 or more | 6% | 9% |
| Mobile homes | 18% | 10% |
| Built before 1960 | 21% | 26% |
| Built since 2000 | 11% | 27% |
| Middle year built | 1979 | 1980 |
| Owner-occupied | 66% | 69% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.