Locations and reports
Radon Levels in Montana
What this means for you
- Your area: EPA rates 49 of Montana's 56 classified counties Zone 1, the highest of its three radon zones. Zones are predictions for whole counties, and homes with elevated levels occur in all three zones.
- Local tests: CDC publishes Montana's radon test results by county. Open your county below to see its figures.
- Your home: The only way to know your home’s level is to test it.
pCi/L (picocuries per liter) is the unit radon is measured in. EPA recommends fixing a home at 4 pCi/L or above, its action level.
For Montana, EPA's Map of Radon Zones places 49 of its 56 classified counties in Zone 1, highest predicted potential, a prediction for each county as a whole. Radon levels vary from home to home, so only a test measures the level in yours.
Predicted: EPA radon zone
56 of 56 counties classified
EPA classifies counties, not states. Of the 56 counties in Montana with a zone, 49 are in Zone 1 and 7 in Zone 2.
- Zone 1: Highest predicted potentialgreater than 4 pCi/L49 of 56 counties · 87.5%
- Zone 2: Moderate predicted potential2 to 4 pCi/L7 of 56 counties · 12.5%
An EPA radon zone describes predicted potential across a whole county. It is not intended to determine whether any individual home should be tested, and homes with elevated levels occur in all three zones. EPA recommends testing every home regardless of zone, and testing is the only way to know the radon level in a specific building.
This is a county-level geologic prediction. It is not a measurement of any address, and houses with elevated radon are found in all three zones.
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
CDC publishes Montana's radon test figures by county: 53 of its 56 counties have one. Each county's share is in the county list.
Montana, In figures
Montana in figures
What the published data says about Montana, in words. A zone and a share of tests describe an area, never the level in any one home.
Predicted
PredictedEPA places 49 of Montana's 56 counties in Zone 1 and 7 in Zone 2.
Zone 1 counties, A to Z, begin with Beaverhead County, Big Horn County and Blaine County; the county section below lists all 49.
Compared
Calculated by Radon41188% of Montana's counties with a zone on file are in Zone 1, a larger share than across all U.S. counties (34%). It is a share of counties, not of land, people or homes.
Reported tests
MeasuredCDC has no statewide testing figure for Montana on file here.
53 of the 56 counties have a published county figure; the most tests in each one's latest year were reported for Missoula County (1,441 in 2017), Gallatin County (1,295 in 2017) and Yellowstone County (1,243 in 2017).
Local record
Montana's radon program is the Radon Control Program, run by Montana DEQ; its contacts are under Local resources.
4 cities have a page setting the figures of the counties it lies in side by side: Kalispell, Bozeman, Billings and Helena.
Montana, Counties
Montana counties by EPA zone
PredictedAll 56 counties, by the zone EPA predicts for each. Every county has its own report.
Zone 1: highest predicted potential49
- Beaverhead County59.5% of reported tests at or above 4 pCi/L, 2017
- Big Horn County28.6% of reported tests at or above 4 pCi/L, 2017
- Blaine County6.7% of reported tests at or above 4 pCi/L, 2017
- Broadwater County56.0% of reported tests at or above 4 pCi/L, 2017
- Carbon County52.2% of reported tests at or above 4 pCi/L, 2017
- Carter CountyReported testing not yet available
- Cascade County29.4% of reported tests at or above 4 pCi/L, 2017
- Chouteau County54.5% of reported tests at or above 4 pCi/L, 2017
- Custer County40.7% of reported tests at or above 4 pCi/L, 2017
- Daniels County0.0% of reported tests at or above 4 pCi/L, 2017
- Dawson County47.5% of reported tests at or above 4 pCi/L, 2017
- Deer Lodge County30.8% of reported tests at or above 4 pCi/L, 2017
- Fallon County62.5% of reported tests at or above 4 pCi/L, 2017
- Fergus County72.4% of reported tests at or above 4 pCi/L, 2017
- Flathead County37.8% of reported tests at or above 4 pCi/L, 2017
- Gallatin County42.8% of reported tests at or above 4 pCi/L, 2017
- Garfield CountyReported testing not yet available
- Glacier County14.3% of reported tests at or above 4 pCi/L, 2017
- Granite County25.0% of reported tests at or above 4 pCi/L, 2017
- Hill County14.8% of reported tests at or above 4 pCi/L, 2017
- Jefferson County71.0% of reported tests at or above 4 pCi/L, 2017
- Judith Basin County64.3% of reported tests at or above 4 pCi/L, 2017
- Lake County40.3% of reported tests at or above 4 pCi/L, 2017
- Lewis and Clark County61.8% of reported tests at or above 4 pCi/L, 2017
- Liberty County33.3% of reported tests at or above 4 pCi/L, 2017
- Lincoln County51.4% of reported tests at or above 4 pCi/L, 2017
- Madison County50.0% of reported tests at or above 4 pCi/L, 2017
- McCone County0.0% of reported tests at or above 4 pCi/L, 2017
- Meagher County0.0% of reported tests at or above 4 pCi/L, 2017
- Mineral County56.7% of reported tests at or above 4 pCi/L, 2017
- Missoula County44.6% of reported tests at or above 4 pCi/L, 2017
- Park County60.0% of reported tests at or above 4 pCi/L, 2017
- Phillips County100.0% of reported tests at or above 4 pCi/L, 2015
- Pondera County0.0% of reported tests at or above 4 pCi/L, 2017
- Powder River County62.5% of reported tests at or above 4 pCi/L, 2017
- Powell County58.6% of reported tests at or above 4 pCi/L, 2017
- Prairie County66.7% of reported tests at or above 4 pCi/L, 2017
- Ravalli County44.6% of reported tests at or above 4 pCi/L, 2017
- Richland County78.6% of reported tests at or above 4 pCi/L, 2017
- Roosevelt County93.8% of reported tests at or above 4 pCi/L, 2017
- Rosebud County40.0% of reported tests at or above 4 pCi/L, 2017
- Sanders County50.0% of reported tests at or above 4 pCi/L, 2017
- Sheridan County75.7% of reported tests at or above 4 pCi/L, 2017
- Silver Bow County70.1% of reported tests at or above 4 pCi/L, 2017
- Stillwater County55.9% of reported tests at or above 4 pCi/L, 2017
- Teton County28.6% of reported tests at or above 4 pCi/L, 2017
- Toole County45.5% of reported tests at or above 4 pCi/L, 2017
- Valley County54.2% of reported tests at or above 4 pCi/L, 2017
- Wibaux County50.0% of reported tests at or above 4 pCi/L, 2017
Zone 2: moderate predicted potential7
- Golden Valley County100.0% of reported tests at or above 4 pCi/L, 2016
- Musselshell County29.4% of reported tests at or above 4 pCi/L, 2017
- Petroleum CountyReported testing not yet available
- Sweet Grass County88.9% of reported tests at or above 4 pCi/L, 2017
- Treasure County100.0% of reported tests at or above 4 pCi/L, 2017
- Wheatland County100.0% of reported tests at or above 4 pCi/L, 2017
- Yellowstone County42.4% of reported tests at or above 4 pCi/L, 2017
Montana, Cities
Cities in Montana with their own page
Radon data is published by county, not by city. Each city page sets the figures of the counties the city lies in side by side.
Montana, Local resources
Local resources in Montana
Who to ask in Montana: the state's radon program, test kits and professionals.
Radon Control Program
Montana DEQ
Montana’s radon program answers questions about testing, mitigation and the rules where you live.
- Phone
- 1-800-546-0483
- Licensing of radon professionals
Montana DEQ does not certify or require proof of certification for the contractors listed.
Test kits
The program says: Energy Bureau staff manage the radon information toll-free hotline and distribute subsidized radon test kits to Montana residents.
Radon professionals
No professionals are listed in Montana yet. The state program can point you to registered testers and mitigators.
See the Montana directoryMontana, Questions
Questions about radon in Montana
Common questions9 questions, answered from the figures above
Is radon a problem in Montana?
EPA's Map of Radon Zones places 49 of the 56 Montana counties it classifies in Zone 1, the highest predicted potential, 7 in Zone 2 and 0 in Zone 3. An EPA radon zone describes predicted potential across a whole county. It is not intended to determine whether any individual home should be tested, and homes with elevated levels occur in all three zones. EPA recommends testing every home regardless of zone, and testing is the only way to know the radon level in a specific building.
Which Montana counties are in EPA radon Zone 1?
49 counties are in Zone 1: Beaverhead County, Big Horn County, Blaine County, Broadwater County, Carbon County, Carter County, Cascade County, Chouteau County, and 41 more in the county table on this page. Zone 1 is EPA's class for highest predicted potential, a predicted average indoor screening level greater than 4 pCi/L. A zone is a prediction for a county, not a measurement of any home.
Radon in Beaverhead CountyRadon in Big Horn CountyRadon in Blaine County
How do I get a radon test in Montana?
EPA says you can test your home yourself or hire a qualified radon test company, and that either approach takes only a small amount of time and effort. The Montana radon program is the place to ask about certified testers and any test kit offer it runs.
How to test a homeFree and low-cost kits by stateMontana radon program
Who does radon mitigation in Montana?
Radon411 has no certified mitigators listed for Montana yet. EPA recommends having a qualified contractor fix a home with a radon problem, because lowering high radon levels takes technical knowledge and special skills, and some states require the work to be done by a licensed or certified professional.
How radon mitigation worksWhat mitigation costsRadon professionals in Montana
Which Montana counties have the highest radon?
56 of Montana's 56 counties have an EPA radon zone published here. Radon411 will not rank counties on data it does not hold, and a zone is a prediction for an area rather than a measurement of any building.
What share of radon tests in Montana are high?
CDC has published no statewide radon testing statistics for Montana, so we cannot give a figure. Where CDC does publish one, the percentage describes radon tests reported to CDC, not homes.
Which EPA region is Montana in?
Montana is in EPA Region 8: Mountains and Plains.
Do I need to test my home in Montana?
Yes, wherever you live in the state. Testing is the only way to know the radon level in a specific building. EPA recommends fixing a home when the radon level is 4 pCi/L or higher. EPA recommends considering a fix when the level is between 2 and 4 pCi/L.
Why does this page show coverage rather than one radon level for Montana?
A statewide figure averages counties with very different geology and very different numbers of reported tests, so it hides more than it shows. The county report is the level at which the EPA zone, the geologic potential and the reported testing statistics are actually published, which is why the county table above links to every one of them.
What these figures mean if you own, buy, sell or rent
The zone counts on this page describe counties across Montana. They are predictions for areas, and none of them measures your building.
- How to test a home
If you own your home
Test the lowest lived-in level; a short-term kit screens in days, a long-term kit reflects the year.
- Buying a house: radon guide
If you are buying
Ask for past results and any system's post-mitigation test, and test during the sale.
- Selling a house: radon guide
If you are selling
Testing before you list puts the timing in your hands; disclosure rules differ by state.
- Radon in rental homes
If you rent, or rent out a home
A tenant can test; a fix is the owner's to make, and duties differ by state.
How long a test has to run, under what conditions, and what EPA says a result means: the testing standard, in full.
Montana, Products
Testing and mitigation products
Whatever the figures for Montana show, only a test tells you about one home.
Testing
- Short-term test kitsPassive detectors exposed for a few days under closed-building conditions, then analyzed by a lab.
- Long-term test kitsDetectors exposed for more than 90 days, for a closer picture of the annual average.
- Continuous monitorsPowered devices that log radon on a repeating cycle, often used for transaction tests.
- Digital detectorsConsumer devices that display a running radon reading without a lab.
- Water radon testsKits for radon dissolved in well water, analyzed by a lab.
Mitigation
- Mitigation fansThe inline fan that keeps a soil depressurization system running, sized by the installer.
- System indicatorsU-tube manometers and fan alarms that show whether a mitigation system is still working.
- Sealing materialsCrack, joint and sump sealing used alongside a mitigation system, not instead of one.
Montana / Next steps
What to do next
Learn
Know what radon is
What radon is, how it gets indoors, and why a county zone is not a reading for your home.
Learn about radonTest
Test the building you live in
Short-term or long-term, where the device goes, and closed-house conditions.
How to testFix
Bring a high level down
How a mitigation system works, and the retest that confirms it.
How mitigation worksFind a pro
Hire a certified professional
Measurement and mitigation professionals by state, with their certifications.
Find a professional
Informational. Follow EPA guidance. EPA says all radon tests should be taken for a minimum of 48 hours, with windows and doors closed from 12 hours before a short-term test.