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 Prairie County, Montana
EPA puts Prairie County in Zone 1, its highest radon zone, and only 3 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
47.3%
Dawson County
- Dawson
- 47.3%
1 of 6 neighbours have 30+ tests, 2006 to 2015
Nearest county
47.3%
Dawson County, 36 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
- Prairie
- 100.0%
- Montana
- 100.0%
Share of land USGS rates moderate or high potential
Tests reported
7
Too few for a share
- Prairie
- 7
- Needed
- 30
2007 to 2016, 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 Prairie 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
Prairie County, At a glance
Prairie County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Prairie County in
USGS geologic potential: High across 99% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Prairie County, 2008 to 2017, laboratory
CDC holds 3 reported tests for Prairie County over the 2008 to 2017 laboratory totals, with a median of 7.6 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Prairie County beside the counties around it is how this page reads it.
What these figures count
Only 3 tests were reported to CDC for Prairie 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).
Prairie County, Compared
Prairie County radon figures, compared
Calculated by Radon411CDC's largest figure for Prairie County rests on 7 tests over the 2007 to 2016 laboratory totals, 2 of them at or above 4 pCi/L, so each test moves its share by 14.3 points and no rank or comparison is drawn from it. Results reached as high as 14.4 pCi/L, with a middle value of 3.3 pCi/L.
Dawson County, the one bordering county with a figure over the 2006 to 2015 laboratory totals, reported 47.3% of its tests at or above 4 pCi/L. Farther out, Richland County (75 miles away) at 75.0%, Valley County (120 miles away) at 50.0% and Sheridan County (135 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 Prairie County in Zone 1, the map's highest label: a predicted county average above 4 pCi/L. USGS geology rates 99% of the county's land high radon potential.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Prairie County, Geology
The ground under Prairie County
PredictedMost of the ground under Prairie County is one class on USGS's geologic map: 98.7% of its land is high radon potential, with 1.3% moderate. 98.7% of it lies in the area the map calls Great Plains, to which USGS gives a radon index of 12, in the high band (12 to 17).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Great Plains | Tertiary sandstone, siltstone, shale, coal. | High | 12 | 98.7% |
| Eastern Great Plains | Cretaceous marine shale and marine and nearshore sandstone, siltstone. | Moderate | 11 | 1.3% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Prairie County beside the ground around it
Prairie County has more high-potential ground than Montana as a whole: 98.7% of its land against 78.5%. Of the 6 counties that border it, 1 has more high-potential ground, McCone County the most at 100%.
The map rates the ground, not the air in any home.
Local help
Prairie County, Local resources
Radon testing and mitigation in Prairie 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
Prairie County, Questions
Questions about radon in Prairie County
Are radon levels high in Prairie County?
Over the 2008 to 2017 laboratory totals, 66.7% of the radon tests reported to CDC for Prairie County, Montana were at or above 4 pCi/L, and the median reported pre-mitigation result was 7.6 pCi/L. Dawson County, the one bordering county with a figure over the 2006 to 2015 laboratory totals, reported 47.3% of its tests at or above 4 pCi/L.
Which counties border Prairie County?
Prairie County borders 6 counties: Custer County, Dawson County, McCone County, Wibaux County, Fallon County and Garfield County.
Products
Prairie County, Products
Testing a home in Prairie County
No CDC figure names Prairie County; the nearest county with one, Dawson County (36 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 Prairie 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
MonitorAEGTEST
HOUND-3786 rechargeable radon monitor with a 3.5-inch color screen
- C-NRPP 2024/25: Not included
- Battery
- Alarm
- Screen
Method: Ion chamber
First reading: Within 10 minutes
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
Prairie County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Prairie County
Explore
Prairie County, Bordering counties
Counties bordering Prairie County
Calculated by Radon411- Radon levels in Fallon CountyEPA zone 1
71.4%at or above 4 pCi/L
Median 5.2 pCi/L · 7 tests
- Radon levels in Wibaux CountyEPA zone 1
50.0%at or above 4 pCi/L
Median 3.0 pCi/L · 4 tests
- Radon levels in Dawson CountyEPA zone 1
47.3%at or above 4 pCi/L
Median 3.5 pCi/L · 55 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 McCone CountyEPA zone 1
25.0%at or above 4 pCi/L
Median 2.5 pCi/L · 4 tests
- Radon levels in Garfield CountyEPA zone 1
No CDC figure for 2006 to 2015; its page reads it against its own neighbours.
Prairie County, Cities and towns
Cities and towns in Prairie County
The Census Bureau estimates 1,112 residents in Prairie County for July 1, 2025, 18 more than in 2020 (+1.6%). Spread over its land, that is 0.6 people to the square mile. Terry, its one incorporated place, has 574 residents, 51.6% of the total. CDC's 7 reported tests for 2007 to 2016 work out to 6.3 per 1,000 residents (2025 estimate), close to Montana's 8.1.
Terry is the one incorporated place here; CDC publishes no figure by town, so it reads Prairie County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Terry | 574 | +2.0% | 51.6% |
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).
Prairie County, Homes
Homes in Prairie County
Prairie County is a place of houses on their own lots: 83% of its 667 homes are detached single-family houses, against 69% across Montana. The homes are older than Montana's as a whole: half were built before 1958 (1980 for Montana), and 52% date from before 1960. Owners live in 76% of the occupied homes (Montana: 69%), so for most households a test and a fix are their own to order.
| Homes | Prairie County | Montana |
|---|---|---|
| Housing units | 667 | 522,939 |
| Detached houses | 83% | 69% |
| In buildings of 5 or more | 1% | 9% |
| Mobile homes | 15% | 10% |
| Built before 1960 | 52% | 26% |
| Built since 2000 | 12% | 27% |
| Middle year built | 1958 | 1980 |
| Owner-occupied | 76% | 69% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.