Long-term kit
RL116 long-term radon test kit
- Lab fee extra
Method: Alpha track
In home: 90 days to 12 months
Locations and reports
Radon Levels in Blaine County, Montana
EPA puts Blaine County in Zone 1, its highest radon zone, and only 15 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
72.2%
Fergus County
- Fergus
- 72.2%
- Hill
- 35.0%
2 of 4 neighbours have 30+ tests, 2006 to 2015
Nearest county
35.0%
Hill County, 55 miles
- Hill
- 35.0%
- Montana
- 47.4%
Share at 4+ pCi/L, 120 tests, 2006 to 2015
Ground above low
100.0%
Level with Montana
- Blaine
- 100.0%
- Montana
- 100.0%
Share of land USGS rates moderate or high potential
Tests reported
17
Too few for a share
- Blaine
- 17
- Needed
- 30
2006 to 2015, 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 Blaine 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
Blaine County, At a glance
Blaine County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Blaine County in
USGS geologic potential: High across 100% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Blaine County, 2008 to 2017, laboratory
CDC holds 15 reported tests for Blaine County over the 2008 to 2017 laboratory totals, with a median of 1.2 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Blaine County beside the counties around it is how this page reads it.
What these figures count
Only 15 tests were reported to CDC for Blaine 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).
Blaine County, Compared
Blaine County radon figures, compared
Calculated by Radon411CDC's largest figure for Blaine County rests on 17 tests over the 2006 to 2015 laboratory totals, 1 of them at or above 4 pCi/L, so each test moves its share by 5.9 points and no rank or comparison is drawn from it. Results reached as high as 4.5 pCi/L, with a middle value of 1.3 pCi/L.
Of the counties bordering it, 2 have a figure over the 2006 to 2015 laboratory totals: Fergus County reported the largest share at or above 4 pCi/L, 72.2%, and Hill County the smallest, 35.0%. Farther out, Valley County (106 miles away) at 50.0%, Judith Basin County (114 miles away) at 64.3% and Cascade County (136 miles away) at 35.9% 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 Blaine County in Zone 1, the map's highest label: a predicted county average above 4 pCi/L. USGS geology rates 100% of the county's land high radon potential.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Blaine County, Geology
The ground under Blaine County
PredictedUSGS's geologic map puts all of Blaine County's mapped land in one class: high radon potential. The map puts 84.7% of Blaine County in the area it calls Great Plains (Glaciated) and 15.3% in Northern Rocky Mountains. USGS gives both a radon index of 13, in the high band (12 to 17).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Great Plains (Glaciated) | Glacial deposits derived from Cretaceous shales containing higher than average amounts of uranium. | High | 13 | 84.7% |
| Northern Rocky Mountains | Granitic, metaigneous, metasedimentary rocks, valley fill colluvium and alluvium. | High | 13 | 15.3% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Blaine County beside the ground around it
Blaine County has more high-potential ground than Montana as a whole: 100% of its land against 78.5%. Of the 4 counties that border it, none has as large a share of high-potential ground; Hill County comes nearest at 100%.
The map rates the ground, not the air in any home.
Local help
Blaine County, Local resources
Radon testing and mitigation in Blaine 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
Blaine County, Questions
Questions about radon in Blaine County
Are radon levels high in Blaine County?
Over the 2008 to 2017 laboratory totals, 6.7% of the radon tests reported to CDC for Blaine County, Montana were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.2 pCi/L. Of the counties bordering it, 2 have a figure over the 2006 to 2015 laboratory totals: Fergus County reported the largest share at or above 4 pCi/L, 72.2%, and Hill County the smallest, 35.0%.
Which counties border Blaine County?
Blaine County borders 4 counties: Phillips County, Hill County, Chouteau County and Fergus County.
Products
Blaine County, Products
Testing a home in Blaine County
No CDC figure names Blaine County; the nearest county with one, Hill County (55 miles away), reported 35.0% 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 Blaine 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
RM-63Pro rechargeable radon monitor with a touchscreen
- C-NRPP 2024/25: Not included
- Battery
- Alarm
- Screen
Method: Semiconductor sensor
Short-term kitKidde
442020 short-term charcoal radon test kit
- Lab fee included
Method: Charcoal
In home: 3 days
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Blaine County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Blaine County
Explore
Blaine County, Bordering counties
Counties bordering Blaine 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 Fergus CountyEPA zone 1
72.2%at or above 4 pCi/L
Median 7.0 pCi/L · 72 tests
- Radon levels in Chouteau CountyEPA zone 1
58.3%at or above 4 pCi/L
Median 5.1 pCi/L · 12 tests
- Radon levels in Hill CountyEPA zone 1
35.0%at or above 4 pCi/L
Median 3.2 pCi/L · 120 tests
Blaine County, Cities and towns
Cities and towns in Blaine County
About 6,860 people live in Blaine County by the Census Bureau's estimate for July 1, 2025, 149 fewer than in 2020 (−2.1%). Spread over its land, that is 1.6 people to the square mile. No town dominates: Chinook, the largest, has 1,155 residents, 16.8% of the total. Together its 2 incorporated places hold 27.8% of those residents; the other 72.2% live outside any of them. Reported testing is thin here: 17 tests over 2006 to 2015, or 2.5 for every 1,000 residents (2025 estimate), where Montana as a whole comes to 7.5.
From Chinook to Harlem, CDC publishes no figure by town: each reads Blaine County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Chinook | 1,155 | −2.0% | 16.8% |
| Harlem | 750 | −2.6% | 10.9% |
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).
Blaine County, Homes
Homes in Blaine County
Blaine County is a place of houses on their own lots: 81% of its 2,824 homes are detached single-family houses, against 69% across Montana. The homes are older than Montana's as a whole: half were built before 1972 (1980 for Montana), and 37% date from before 1960. 63% 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 | Blaine County | Montana |
|---|---|---|
| Housing units | 2,824 | 522,939 |
| Detached houses | 81% | 69% |
| In buildings of 5 or more | 3% | 9% |
| Mobile homes | 7% | 10% |
| Built before 1960 | 37% | 26% |
| Built since 2000 | 14% | 27% |
| Middle year built | 1972 | 1980 |
| Owner-occupied | 63% | 69% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.