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Radon in Billings, Montana

EPA puts Yellowstone County, where Billings is, in Zone 2, its middle radon zone, and high results are common there: 42.4% of the 1,520 radon tests reported to CDC (2008 to 2017, laboratory totals) came back at or above 4 pCi/L. Homes with elevated levels occur in all three zones, so only a test measures yours.

Data checked By Radon411Methodology

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  • Share at 4+ pCi/L

    42.4%

    3.1 pts below MT

    Yellowstone
    42.4%
    Montana
    45.5%

    Yellowstone, 20th of 23 in MT, 2008 to 2017

  • Median result

    3.4pCi/L

    Below action level

    Yellowstone
    3.4 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of Yellowstone's tests, 2008 to 2017

  • Nearest county

    55.9%

    Stillwater, 42 miles

    Stillwater
    55.9%
    Yellowstone
    42.4%

    59 tests, 2008 to 2017

  • EPA radon zone

    Zone 2

    Moderate potential

    1. 1
    2. Zone 2
    3. 3

    1 highest, 3 lowest

    Yellowstone, where Billings is

  • Tests reported

    1,520

    In Yellowstone

    Yellowstone
    1,520
    Stillwater
    59

    Reported to CDC before any fix, 2008 to 2017

Read a result for Billings

Starts at Yellowstone County's median, 3.4 pCi/L

3.4pCi/L

EPA’s own thresholds; the figures are the area’s, never this home’s.

EPA’s reading of 3.4 pCi/L

Between 2 and 4 pCi/L

  1. Under 20 to 1.9 pCi/L
  2. 2 to 4consider a fix
  3. 4 and aboveEPA says fix it

This result is between 2 and 4 pCi/L. EPA recommends considering a fix when the level is between 2 and 4 pCi/L. Yellowstone County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Billings, What is published

What is published for Billings

Information:

Every figure for Billings is a county's

Radon data is published by county, not by city, so for Billings it is Yellowstone County's: its EPA zone (Zone 2) and the 1,520 tests reported to CDC for 2008 to 2017, laboratory. Only a test tells you about one home.

Billings covers 44.8 square miles of land, all of it in Yellowstone County. About 121,239 people live there, 2,707 to the square mile.

Billings, Counties

The county Billings lies in

Measured

Yellowstone County's EPA zone and the figures CDC publishes for it, 2008 to 2017, laboratory.

Yellowstone CountyZone 2Moderate predicted potential

42.4%
Reported tests at or above 4 pCi/L
3.4 pCi/L
Median reported result
1,520 tests
Tests reported to CDC
None
Yearly figures on file

Yellowstone County ranks 20th of 23 Montana counties with 30 or more tests for that period, 3.1 points below the 45.5% pooled across Montana's counties, 6.7 points above the national pool of 35.7%.

The counties nearest Billings with a CDC figure for 2008 to 2017, laboratory, measured from the middle of the city: Stillwater County (42 miles, 55.9% of 59 tests), Carbon County (45 miles, 52.2% of 46 tests) and Park County (98 miles, 60.0% of 150 tests). Across the 8 nearest, the share at or above 4 pCi/L runs from 29.4% to 72.4%; the farthest of them, Cascade County, is 170 miles away at 29.4%.

No business in the directory gives Billings as its address; the Montana list covers it. Montana's other cities with a page of their own: Bozeman, Kalispell, Boulder and Helena.

The counties around Billings

By distance from the middle of Billings; counties with 30 or more tests.

Nearest counties to Billings with 30 or more tests
CountyDistanceTestsAt or above 4 pCi/LMedian
Stillwater County42 mi5955.9%4.8 pCi/L
Carbon County45 mi4652.2%4.2 pCi/L
Park County98 mi15060.0%5.3 pCi/L
Fergus County107 mi7672.4%7.2 pCi/L
Judith Basin County119 mi4264.3%5.9 pCi/L
Gallatin County128 mi1,60042.8%3.2 pCi/L
Madison County167 mi5850.0%3.9 pCi/L
Cascade County170 mi23529.4%1.7 pCi/L

Predicted: EPA Map of Radon Zones, by county. Measured: CDC tracking data, by county, 2008 to 2017, laboratory.

Billings, Geology

The ground under Billings

Predicted

USGS's geologic map puts all of Billings' mapped land in one class: moderate radon potential. All of it lies in the area the map calls Plains and Mountains, to which USGS gives a radon index of 10, in the moderate band (9 to 11).

USGS's geologic areas under Billings
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Plains and MountainsMarine and continental shale, siltstone, and sandstone of Cretaceous and Tertiary ages, and volcanic rocks.Moderate10100%

Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.

Billings beside its county and Montana

All of Billings, like all of Yellowstone County, is rated moderate. Across Montana 78.5% of the land is rated high; none of Billings' is.

Share of land by USGS radon potential: Billings, the county it lies in and Montana
AreaEPA zoneLow potentialModerate potentialHigh potential
BillingsBy countyNone100%None
Yellowstone CountyZone 2None100%None
Montana56 counties, pooled by land areaVariesNone21.5%78.5%

The map rates the ground, not the air in any home.

Billings, Homes

Homes in Billings

Of Billings' 53,537 homes, 63% are detached houses, against 66% across Yellowstone County; 14% are in buildings of five or more homes. Half of its homes were built before 1979, close to Yellowstone County's 1982: 26% date from before 1960 and 26% from 2000 or later. 65% of occupied homes are lived in by their owner (Yellowstone County: 69%); in the rest a tenant can run a test, but a fix is the landlord's to make.

Homes in Billings, Yellowstone County, Montana, 2019 to 2023
HomesBillingsYellowstone CountyMontana
Housing units53,53773,363522,939
Detached houses63%66%69%
In buildings of 5 or more14%11%9%
Mobile homes6%10%10%
Built before 196026%23%26%
Built since 200026%27%27%
Middle year built197919821980
Owner-occupied65%69%69%

Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.

Local help

Billings, Local resources

Local resources for Billings

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

The program's own words on licensing are on the Montana page.

What it means

Billings, Questions

Questions about radon in Billings

What radon zone is Billings in?

Billings has no zone of its own: it shares Yellowstone County's, Zone 2, the map's middle class: a predicted county average of 2 to 4 pCi/L.

What are radon levels in Billings?

42.4% of the 1,520 tests reported from Yellowstone County for 2008 to 2017 (laboratory totals) were at or above 4 pCi/L, the level at which EPA says to fix a home: high results are ordinary around Billings. The median reported result was 3.4 pCi/L.

Should I test my home in Billings?

Yes. About 644 of the 1,520 tests reported from Yellowstone County were at or above 4 pCi/L. That is below Montana's pooled 45.5%, and still not a reason to skip it, and ranks Yellowstone County 20th of the 23 Montana counties with 30 or more tests. No map says which homes those are. How to test a home.

What ground is Billings built on, as far as radon goes?

USGS's geologic map puts all of Billings on one named area, "Plains and Mountains", rated moderate for radon potential, radon index 10.

Is radon higher in the counties around Billings?

Some are and some are not. Against Yellowstone County's 42.4%, 7 of the 8 nearest counties with a figure report more and 1 less, from Cascade County (29.4%, 170 miles off) to Fergus County (72.4%, 107 miles off).

The answers use the published figures of Yellowstone County, the county Billings lies in.

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