Skip to content
RADON411

Locations and reports

Montana Radon Map and Levels by County

Montana's counties span EPA Zones 1 and 2. Homes with elevated levels occur in all three zones, so only a test measures yours.

Data checked By Radon411Methodology

Predicted
49 of 56counties in Zone 1, EPA's highest radon zone
Measured
By countyCDC publishes Montana's test figures by county: 53 of 56 counties have one.
Your home
Test to knowNo area figure here is a reading of your home.
How to test this homeFind a certified tester

The data

Montana, At a glance

Montana at a glance

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.

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

CDC test figures, county by county

CDC publishes Montana's radon test figures by county: 53 of its 56 counties have one. Each one's share is in the county list.

Montana, Counties

Montana counties by EPA zone

Predicted

Montana's radon map, then all 56 counties by the zone EPA predicts for each, highest reported share of tests at or above 4 pCi/L first. Each has its own report.

Montana radon map by county: EPA radon zones. Map of Montana's 56 counties shaded by EPA radon zone: Zone 1 in red-orange, Zone 2 in amber. 49 in Zone 1, 7 in Zone 2, 0 in Zone 3.
Montana radon map by countyEPA radon zones for Montana's counties: 49 counties in Zone 1, 7 counties in Zone 2, 0 counties in Zone 3.Predicted potential for each county, not a reading of any home. Homes with elevated levels of radon have been found in all three zones.

Zone 1: highest predicted potential49

Local help

Montana, Local resources

Local resources in Montana

Who to ask in Montana: its radon program, test kits and professionals.

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.

Radon Action Brief

National Radon Action MonthPre-sale

The radon brief for your Montana county, in one dated file.

  • Your area's radon record, explained.
  • Your plan to test this week.
  • Fix costs and pros near you.

Save 64%Sale price: $8.99Price after the sale: $25Ends Jan 31Then $25

Get your Montana county's BriefSee a free sample

Area data, not a test of the building.

What it means

Montana, Questions

Questions about radon in Montana

Common questions

9 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.

Montana on the radon mapRadon levels by state

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's Montana directory lists 1 radon business for testing, mitigation or both, each with the licensing list it was read from. 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.

If you own, buy, sell or rent

What these figures mean for each reader, with the guide that covers it

The zone counts on this page describe counties across Montana. They are predictions for areas, and none of them measures your building.

Montana in figures

The figures above, said in words

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

      Predicted

      EPA 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 Radon411

      88% 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

    Measured

    CDC 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 (2,613 tests over 2008 to 2017, laboratory), Gallatin County (1,600 tests over 2008 to 2017, laboratory) and Yellowstone County (1,520 tests over 2008 to 2017, laboratory).

  • 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: Bozeman, Kalispell, Billings and Helena.

Products

Montana, Products

Testing and mitigation products

Whatever the figures for Montana show, only a test tells you about one home.

Test kits and monitors42

See all products

As an Amazon Associate, Radon411 earns from qualifying purchases.

Best radon monitors for Montana homes, compared

Testing

5

Mitigation

3

Explore

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, Next steps

What to do next

  1. LearnKnow what radon isWhat radon is, how it gets indoors, and why a county zone is not a reading for your home.Learn about radon
  2. TestTest the building you live inShort-term or long-term, where the device goes, and closed-house conditions.How to test
  3. FixBring a high level downHow a mitigation system works, and the retest that confirms it.How mitigation works
  4. Find a proHire a certified professionalMeasurement 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.