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 Phillips County, Montana
EPA puts Phillips County in Zone 1, its highest radon zone, and only 2 radon tests from it are on file with CDC (2006 to 2015, 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%
- Valley
- 50.0%
2 of 5 neighbours have 30+ tests, 2006 to 2015
Nearest county
50.0%
Valley County, 58 miles
- Valley
- 50.0%
- Montana
- 47.4%
Share at 4+ pCi/L, 40 tests, 2006 to 2015
Ground above low
100.0%
Level with Montana
- Phillips
- 100.0%
- Montana
- 100.0%
Share of land USGS rates moderate or high potential
Tests reported
2
Too few for a share
- Phillips
- 2
- 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 Phillips 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
Phillips County, At a glance
Phillips County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Phillips 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 Phillips County, 2006 to 2015, laboratory
CDC holds 2 reported tests for Phillips County over the 2006 to 2015 laboratory totals, with a median of 6.2 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Phillips County beside the counties around it is how this page reads it.
What these figures count
Only 2 tests were reported to CDC for Phillips County over 2006 to 2015 (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: 2006 to 2015, laboratory. Measured data period: 2005 to 2015 (every CDC figure on file).
Phillips County, Compared
Phillips County radon figures, compared
Calculated by Radon411CDC's largest figure for Phillips County rests on 2 tests over the 2006 to 2015 laboratory totals, 2 of them at or above 4 pCi/L, so each test moves its share by 50.0 points and no rank or comparison is drawn from it. Results reached as high as 8.2 pCi/L, with a middle value of 6.2 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 Valley County the smallest, 50.0%. Farther out, Hill County (104 miles away) at 35.0%, Judith Basin County (138 miles away) at 64.3% and Dawson County (156 miles away) at 47.3% 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 Phillips 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.
Phillips County, Geology
The ground under Phillips County
PredictedUSGS's geologic map puts all of Phillips County's mapped land in one class: high radon potential. 96.1% of it lies in the area the map calls Great Plains (Glaciated), to which USGS gives 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 | 96.1% |
| Northern Rocky Mountains | Granitic, metaigneous, metasedimentary rocks, valley fill colluvium and alluvium. | High | 13 | 3.9% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Phillips County beside the ground around it
Phillips County has more high-potential ground than Montana as a whole: 100% of its land against 78.5%. Of the 5 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
Phillips County, Local resources
Radon testing and mitigation in Phillips 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
Phillips County, Questions
Questions about radon in Phillips County
Are radon levels high in Phillips County?
Over the 2006 to 2015 laboratory totals, 100.0% of the radon tests reported to CDC for Phillips County, Montana were at or above 4 pCi/L, and the median reported pre-mitigation result was 6.2 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 Valley County the smallest, 50.0%.
Which counties border Phillips County?
Phillips County borders 5 counties: Blaine County, Valley County, Garfield County, Petroleum County and Fergus County.
Products
Phillips County, Products
Testing a home in Phillips County
No CDC figure names Phillips County; the nearest county with one, Valley County (58 miles away), reported 50.0% 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 Phillips 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-3699 radon monitor with a 2.1-inch touchscreen
- C-NRPP 2024/25: Not included
- Battery
- Alarm
- Screen
First reading: Within 1 hour
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
Phillips County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Phillips County
Explore
Phillips County, Bordering counties
Counties bordering Phillips County
Calculated by Radon411- 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 Valley CountyEPA zone 1
50.0%at or above 4 pCi/L
Median 4.2 pCi/L · 40 tests
- Radon levels in Blaine CountyEPA zone 1
5.9%at or above 4 pCi/L
Median 1.3 pCi/L · 17 tests
- 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.
Phillips County, Cities and towns
Cities and towns in Phillips County
Phillips County's population has barely moved since 2020: 4,203 residents on July 1, 2025 against 4,208 then, by the Census Bureau's estimates. Spread over its land, that is 0.8 people to the square mile. Its largest town, Malta, has 1,846 residents, 43.9% of the total. Together its 3 incorporated places hold 50.6% of those residents; the other 49.4% live outside any of them. Reported testing is thin here: 2 tests over 2006 to 2015, or 0.5 for every 1,000 residents (2025 estimate), where Montana as a whole comes to 7.5.
From Malta to Dodson, CDC publishes no figure by town: each reads Phillips County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Malta | 1,846 | −0.2% | 43.9% |
| Saco | 159 | −0.6% | 3.8% |
| Dodson | 123 | −0.8% | 2.9% |
3 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).
Phillips County, Homes
Homes in Phillips County
Phillips County is a place of houses on their own lots: 78% of its 2,235 homes are detached single-family houses, against 69% across Montana. The homes are older than Montana's as a whole: half were built before 1971 (1980 for Montana), and 37% date from before 1960. 75% 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 | Phillips County | Montana |
|---|---|---|
| Housing units | 2,235 | 522,939 |
| Detached houses | 78% | 69% |
| In buildings of 5 or more | 2% | 9% |
| Mobile homes | 15% | 10% |
| Built before 1960 | 37% | 26% |
| Built since 2000 | 14% | 27% |
| Middle year built | 1971 | 1980 |
| Owner-occupied | 75% | 69% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.