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 Hill County, Montana
EPA puts Hill County in Zone 1, its highest radon zone, and only 27 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
Share at 4+ pCi/L
35.0%
12.4 pts below MT
- Hill
- 35.0%
- Montana
- 47.4%
120 tests, 2006 to 2015
Median result
3.2pCi/L
Below action level
- Hill
- 3.2 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2006 to 2015
Tests reported
120
11th of 24 by tests
- Hill
- 120
- Missoula
- 2,122
Reported to CDC before any fix, 2006 to 2015
EPA radon zone
Zone 1
Highest potential
- Zone 1
- 2
- 3
1 highest, 3 lowest
EPA predicts over 4 pCi/L indoors
Rank in Montana
24 of 24
Lowest quarter
- Hill
- 35.0%
- Sheridan
- 75.7%
By share, of 24 with 30+ tests
Read a result for Hill County
Starts at Hill County's median, 3.2 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 3.2 pCi/L
Between 2 and 4 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 4 and aboveEPA says fix it
This result is between 2 and 4 pCi/L. EPA recommends considering a fix when the level is between 2 and 4 pCi/L. Hill County's median reported result, 2006 to 2015.
The data
Hill County, At a glance
Hill County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Hill 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 Hill County, 2008 to 2017, laboratory
CDC holds 27 reported tests for Hill County over the 2008 to 2017 laboratory totals, with a median of 2.1 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Hill County beside the counties around it is how this page reads it.
What these figures count
Only 27 tests were reported to CDC for Hill 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).
Hill County, Compared
Hill County radon figures, compared
Calculated by Radon411In Hill County, about 4 in 10 reported tests over the 2006 to 2015 laboratory totals (42 of 120) were at or above EPA's action level. Against the national pool of 36.3%, the gap is 1.3 points lower. Across 52 Montana counties pooled together, 47.4% of tests reached that level, so Hill County runs 12.4 points below its state.
The newest figure, over the 2008 to 2017 laboratory totals, counts only 27 tests (14.8% at or above 4 pCi/L), too few to compare, so this reading uses the 120-test figure.
By share, Hill County is 24th of 24 Montana counties with 30 or more tests for the same period.
Half the tests came in under 3.2 pCi/L and half over it; the single highest reached 249.8 pCi/L. Below the action level, 38 tests (31.7%) came in under 2 pCi/L, against 27.8% statewide, and 40 tests (33.3%) fell between 2 and 4, against 24.8% statewide.
Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 35.0% share point the same way here. USGS geology rates 100% of the county's land high radon potential.
CDC's ten-year totals for Hill County went from 118 tests (2005 to 2014) to 27 (2008 to 2017), the share going from 34.7% to 14.8%.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Hill County, Geology
The ground under Hill County
PredictedUSGS's geologic map puts all of Hill County's mapped land in one class: high radon potential. The map puts 90.6% of Hill County in the area it calls Great Plains (Glaciated) and 9.4% 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 | 90.6% |
| Northern Rocky Mountains | Granitic, metaigneous, metasedimentary rocks, valley fill colluvium and alluvium. | High | 13 | 9.4% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Hill County beside the ground around it
Hill County has more high-potential ground than Montana as a whole: 100% of its land against 78.5%. Of the 3 counties that border it, none has as large a share of high-potential ground; Blaine County comes nearest at 100%.
The map rates the ground, not the air in any home.
Local help
Hill County, Local resources
Radon testing and mitigation in Hill 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
Hill County, Questions
Questions about radon in Hill County
Are radon levels high in Hill County?
Over the 2008 to 2017 laboratory totals, 14.8% of the radon tests reported to CDC for Hill County, Montana were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.1 pCi/L. Of 24 Montana counties with 30 or more tests for the same period, 23 reported a higher share; pooled, the state comes to 47.4%.
Which counties border Hill County?
Hill County borders 3 counties: Liberty County, Chouteau County and Blaine County.
Products
Hill County, Products
Testing a home in Hill County
In Hill County, 35.0% of 120 tests reported to CDC over the 2006 to 2015 laboratory totals reached 4 pCi/L, against 47.4% pooled across Montana. In Zone 1 the year-round level in Hill 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
MonitorForensics Detectors
FD-65-RADON rechargeable radon detector with a color screen
- C-NRPP 2024/25: Not included
- Battery
- Alarm
- Screen
Method: Semiconductor sensor
First reading: Within 6 hours
Short-term kitempowerDX
Standard Radon Test short-term mail-in radon test kit
- Lab fee included
Method: Passive sampler
In home: 48 to 96 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Hill County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Hill County
Explore
Hill County, Bordering counties
Counties bordering Hill County
Calculated by Radon411- Radon levels in Chouteau CountyEPA zone 1
58.3%at or above 4 pCi/L
Median 5.1 pCi/L · 12 tests · 23.3 points above Hill County
- Radon levels in Liberty CountyEPA zone 1
33.3%at or above 4 pCi/L
Median 3.8 pCi/L · 3 tests · 1.7 points below Hill County
- Radon levels in Blaine CountyEPA zone 1
5.9%at or above 4 pCi/L
Median 1.3 pCi/L · 17 tests · 29.1 points below Hill County
Hill County, Cities and towns
Cities and towns in Hill County
Hill County's population has barely moved since 2020: 16,167 residents on July 1, 2025 against 16,248 then, by the Census Bureau's estimates. Spread over its land, that is 5.6 people to the square mile. Havre alone is home to 9,264 of them, 57.3% of the total. Together its 2 incorporated places hold 58.1% of those residents; the other 41.9% live outside any of them. CDC's 120 reported tests for 2006 to 2015 work out to 7.4 per 1,000 residents (2025 estimate), close to Montana's 7.5.
From Havre to Hingham, CDC publishes no figure by town: each reads Hill County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Havre | 9,264 | −0.7% | 57.3% |
| Hingham | 127 | −2.3% | 0.8% |
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).
Hill County, Homes
Homes in Hill County
Of Hill County's 7,232 homes, 72% are detached houses, against 69% across Montana; 14% are mobile homes. The homes are older than Montana's as a whole: half were built before 1972 (1980 for Montana), and 36% date from before 1960. 67% 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 | Hill County | Montana |
|---|---|---|
| Housing units | 7,232 | 522,939 |
| Detached houses | 72% | 69% |
| In buildings of 5 or more | 5% | 9% |
| Mobile homes | 14% | 10% |
| Built before 1960 | 36% | 26% |
| Built since 2000 | 12% | 27% |
| Middle year built | 1972 | 1980 |
| Owner-occupied | 67% | 69% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.