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 Fallon County, Montana
EPA puts Fallon County in Zone 1, its highest radon zone, and only 8 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
69.6%
Bowman County
- Bowman
- 69.6%
1 of 8 neighbours have 30+ tests, 2006 to 2015
Nearest county
47.3%
Dawson County, 68 miles
- Dawson
- 47.3%
- Montana
- 47.4%
Share at 4+ pCi/L, 55 tests, 2006 to 2015
Ground above low
100.0%
Level with Montana
- Fallon
- 100.0%
- Montana
- 100.0%
Share of land USGS rates moderate or high potential
Tests reported
8
Too few for a share
- Fallon
- 8
- Needed
- 30
2008 to 2017, 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 Fallon 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
Fallon County, At a glance
Fallon County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Fallon County in
USGS geologic potential: High across 69% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Fallon County, 2008 to 2017, laboratory
CDC holds 8 reported tests for Fallon County over the 2008 to 2017 laboratory totals, with a median of 4.7 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Fallon County beside the counties around it is how this page reads it.
What these figures count
Only 8 tests were reported to CDC for Fallon 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).
Fallon County, Compared
Fallon County radon figures, compared
Calculated by Radon411CDC's largest figure for Fallon County rests on 8 tests over the 2008 to 2017 laboratory totals, 5 of them at or above 4 pCi/L, so each test moves its share by 12.5 points and no rank or comparison is drawn from it. Results reached as high as 143.9 pCi/L, with a middle value of 4.7 pCi/L.
Bowman County, ND, the one bordering county with a figure over the 2006 to 2015 laboratory totals, reported 69.6% of its tests at or above 4 pCi/L. Farther out, Dawson County (68 miles away) at 47.3%, Richland County (101 miles away) at 75.0% and Sheridan County (165 miles away) at 75.7% 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 Fallon 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.
Fallon County, Geology
The ground under Fallon County
PredictedUSGS's geologic map splits Fallon County: 68.9% of its land is high radon potential and 31.1% moderate. The map puts 68.9% of Fallon County in the area it calls Great Plains and 31.1% in Eastern Great Plains. USGS gives the first a radon index of 12, in the high band (12 to 17), and the second 11, 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 | 68.9% |
| Eastern Great Plains | Cretaceous marine shale and marine and nearshore sandstone, siltstone. | Moderate | 11 | 31.1% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Fallon County beside the ground around it
On high-potential ground Fallon County is close to Montana as a whole: 68.9% of its land against 78.5%. Of the 8 counties that border it, 6 have more high-potential ground, Golden Valley County, ND the most at 100%.
The map rates the ground, not the air in any home.
Local help
Fallon County, Local resources
Radon testing and mitigation in Fallon 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
Fallon County, Questions
Questions about radon in Fallon County
Are radon levels high in Fallon County?
Over the 2008 to 2017 laboratory totals, 62.5% of the radon tests reported to CDC for Fallon County, Montana were at or above 4 pCi/L, and the median reported pre-mitigation result was 4.7 pCi/L. Bowman County, ND, the one bordering county with a figure over the 2006 to 2015 laboratory totals, reported 69.6% of its tests at or above 4 pCi/L.
Which counties border Fallon County?
Fallon County borders 8 counties: Bowman County, ND, Golden Valley County, ND, Slope County, ND, Wibaux County, MT, Custer County, MT, Carter County, MT, Prairie County, MT and Harding County, SD.
Products
Fallon County, Products
Testing a home in Fallon County
No CDC figure names Fallon County; the nearest county with one, Dawson County (68 miles away), reported 47.3% 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 Fallon 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-65 rechargeable radon detector with a color screen and alarm
- C-NRPP 2024/25: Not included
- Battery
- Alarm
- Screen
Method: Semiconductor sensor
First reading: Within 6 hours
Short-term kit
RA100 short-term liquid scintillation radon test kit
- Lab fee extra
Method: Liquid scintillation
In home: 48 to 96 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Fallon County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Fallon County
Explore
Fallon County, Bordering counties
Counties bordering Fallon County
Calculated by Radon411- Radon levels in Harding County, SDEPA zone 2
100.0%at or above 4 pCi/L
Median 7.9 pCi/L · 2 tests
- Radon levels in Slope County, NDEPA zone 1
75.0%at or above 4 pCi/L
Median 15.0 pCi/L · 16 tests
- Radon levels in Bowman County, NDEPA zone 1
69.6%at or above 4 pCi/L
Median 5.8 pCi/L · 46 tests
- Radon levels in Wibaux County, MTEPA zone 1
50.0%at or above 4 pCi/L
Median 3.0 pCi/L · 4 tests
- Radon levels in Custer County, MTEPA zone 1
37.9%at or above 4 pCi/L
Median 3.4 pCi/L · 29 tests
- Radon levels in Golden Valley County, NDEPA zone 1
29.4%at or above 4 pCi/L
Median 2.7 pCi/L · 17 tests
- Radon levels in Prairie County, MTEPA zone 1
28.6%at or above 4 pCi/L
Median 3.3 pCi/L · 7 tests
- Radon levels in Carter County, MTEPA zone 1
No CDC figure for 2006 to 2015; its page reads it against its own neighbours.
Fallon County, Cities and towns
Cities and towns in Fallon County
About 2,959 people live in Fallon County by the Census Bureau's estimate for July 1, 2025, 70 fewer than in 2020 (−2.3%). Spread over its land, that is 1.8 people to the square mile. Baker alone is home to 1,776 of them, 60.0% of the total. Together its 2 incorporated places hold 65.8% of those residents; the other 34.2% live outside any of them. Reported testing is thin here: 8 tests over 2008 to 2017, or 2.7 for every 1,000 residents (2025 estimate), where Montana as a whole comes to 8.6.
From Baker to Plevna, CDC publishes no figure by town: each reads Fallon County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Baker | 1,776 | −0.9% | 60.0% |
| Plevna | 171 | −3.4% | 5.8% |
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).
Fallon County, Homes
Homes in Fallon County
Of Fallon County's 1,451 homes, 70% are detached houses, against 69% across Montana; 18% are mobile homes. Half of its homes were built before 1978, close to Montana's 1980: 28% date from before 1960 and 24% 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 | Fallon County | Montana |
|---|---|---|
| Housing units | 1,451 | 522,939 |
| Detached houses | 70% | 69% |
| In buildings of 5 or more | 6% | 9% |
| Mobile homes | 18% | 10% |
| Built before 1960 | 28% | 26% |
| Built since 2000 | 24% | 27% |
| Middle year built | 1978 | 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.