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Radon Levels in Caribou County, Idaho

EPA puts Caribou County in Zone 2, its middle radon zone, and high results are common there: 43.9% of the 57 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

    43.9%

    2.4 pts above ID

    Caribou
    43.9%
    Idaho
    41.5%

    57 tests, 2008 to 2017

  • Median result

    3.4pCi/L

    Below action level

    Caribou
    3.4 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    57

    30th of 37 by tests

    Caribou
    57
    Ada
    3,030

    Reported to CDC before any fix, 2008 to 2017

  • EPA radon zone

    Zone 2

    Moderate potential

    1. 1
    2. Zone 2
    3. 3

    1 highest, 3 lowest

    EPA predicts 2 to 4 pCi/L indoors

  • Rank in Idaho

    15 of 37

    Middle half

    Caribou
    43.9%
    Bear Lake
    78.1%

    By share, of 37 with 30+ tests

Read a result for Caribou County

Starts at Caribou 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. Caribou County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Caribou County, At a glance

Caribou County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

Caribou County is a county: EPA's forecast for it as a whole is an average indoor of 2 to 4 pCi/L (75 to 150 Bq/m³). It describes no single address, and homes above EPA's are found in every zone, this one included.

USGS geologic potential: Moderate across 100% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Caribou County, 2008 to 2017, laboratory

Reported results by concentration band, Caribou County, 2008 to 2017, laboratory
Under 2 pCi/L: 28%2 to 4 pCi/L: 28%4 pCi/L and above: 44%

Of 57 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Caribou County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L1628.1%
2 to 4 pCi/L1628.1%
4 pCi/L and above2543.9%
What these figures count

These are the 57 tests reported to CDC for Caribou County over 2008 to 2017 (laboratory totals), many from homes being sold or already suspected of a problem: they describe the county's reported tests, not this house.

Measured: CDC tracking data. Figure above: 2008 to 2017, laboratory. Measured data period: 2005 to 2017 (every CDC figure on file).

How to read these figures

Caribou County, Compared

Caribou County radon figures, compared

Calculated by Radon411

In Caribou County, about 4 in 10 reported tests over the 2008 to 2017 laboratory totals (25 of 57) were at or above EPA's action level. Against the national pool of 35.7%, the gap is 8.2 points higher. Across 44 Idaho counties pooled together, 41.5% of tests reached that level, so Caribou County runs 2.4 points above its state.

Of 6 neighbours with a figure, 3 reported a larger share at or above 4 pCi/L and 3 a smaller one; the spread is 34.7% (Franklin County) to 78.1% (Bear Lake County). By share, Caribou County is 15th of 37 Idaho counties with 30 or more tests for the same period.

Half the tests came in under 3.4 pCi/L and half over it; the single highest reached 22.9 pCi/L. Below the action level, 16 tests (28.1%) came in under 2 pCi/L, against 31.5% statewide, and 16 tests (28.1%) fell between 2 and 4, against 26.9% statewide.

Zone 2 on EPA's map (predicted average between 2 and 4 pCi/L) and a 43.9% share point the same way here. USGS geology rates 100% of the county's land moderate radon potential.

CDC's ten-year totals for Caribou County went from 70 tests (2005 to 2014) to 57 (2008 to 2017), the share going from 41.4% to 43.9%.

Caribou County against Idaho, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Caribou County
Caribou County5743.9%3.4 pCi/LThis county
Idaho, pooled44 counties, pooled12,96141.5%Not pooled−2.4 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−8.2 points
Custer Countyhighest in the state3372.7%6.8 pCi/L+28.8 points
Payette Countylowest in the state614.9%1.5 pCi/L−39.0 points
Bear Lake County, IDborders it3278.1%7.8 pCi/L+34.2 points
Lincoln County, WYborders it14268.3%7.8 pCi/L+24.4 points
Bingham County, IDborders it44652.0%4.2 pCi/L+8.1 points
Bannock County, IDborders it73241.9%3.2 pCi/L−2.0 points
Bonneville County, IDborders it1,11740.1%3.4 pCi/L−3.8 points
Franklin County, IDborders it7534.7%3.1 pCi/L−9.2 points
Where Caribou County's reported results fell, 2008 to 2017, laboratory, beside Idaho and the United States
ResultCaribou County testsCaribou County shareIdaho shareU.S. shareAgainst Idaho
Under 2 pCi/L1628.1%31.5%39.6%−3.4 points
2 to 4 pCi/L1628.1%26.9%24.7%+1.2 points
4 pCi/L and above2543.9%41.5%35.7%+2.4 points
Caribou County ranked among the 37 Idaho counties with 30 or more tests, by share at or above 4 pCi/L, 2008 to 2017, laboratory
CountyRankTestsAt or above 4 pCi/LMedian
Teton County10 of 3747353.3%4.4 pCi/L
Bingham County11 of 3744652.0%4.2 pCi/L
Adams County12 of 373151.6%4.0 pCi/L
Fremont County13 of 3710149.5%3.9 pCi/L
Elmore County14 of 3715848.1%3.8 pCi/L
Caribou County15 of 375743.9%3.4 pCi/L
Bannock County16 of 3773241.9%3.2 pCi/L
Bonneville County17 of 371,11740.1%3.4 pCi/L
Idaho County18 of 379040.0%2.9 pCi/L
Franklin County19 of 377534.7%3.1 pCi/L
Bonner County20 of 3732133.0%2.3 pCi/L
Caribou County ten-year laboratory totals, against Idaho's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestIdaho, pooledChange from the row before
2008 to 20175743.9%3.4 pCi/L22.9 pCi/L41.5%+0.3 points
2007 to 20165543.6%3.5 pCi/L22.9 pCi/L40.8%+1.6 points
2006 to 20156942.0%3.4 pCi/L22.9 pCi/L41.3%+0.6 points
2005 to 20147041.4%3.3 pCi/L22.9 pCi/L41.1%First on file

Pooled shares: Radon411's sum of CDC's county counts for one period.

Caribou County, Geology

The ground under Caribou County

Predicted

USGS's geologic map puts all of Caribou County's mapped land in one class: moderate radon potential. The map puts 51.6% of Caribou County in the area it calls Basin and Range and 48.3% in Middle Rocky Mountain province. USGS gives both a radon index of 11, in the moderate band (9 to 11).

USGS's geologic areas under Caribou County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Basin and RangeCenozoic to Paleozoic sedimentary rocks.Moderate1151.6%
Middle Rocky Mountain provinceComplexly folded, faulted, and metamorphosed rocks of volcanic origin.Moderate1148.3%

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

Caribou County beside the ground around it

Across Idaho 50.7% of the land is rated high; none of Caribou County's is. Of the 6 counties that border it, 4 have more high-potential ground, Lincoln County, WY the most at 37.5%.

Share of land by USGS radon potential: Caribou County, the 6 counties bordering it and Idaho
AreaEPA zoneLow potentialModerate potentialHigh potential
Caribou CountyZone 2None100%None
Bannock CountyZone 2None100%None
Bear Lake CountyZone 2None96.7%3.3%
Franklin CountyZone 2None68.4%31.6%
Bonneville CountyZone 2None92.4%7.6%
Lincoln County, WYZone 1None62.5%37.5%
Bingham CountyZone 2None100%None
Idaho44 counties, pooled by land areaVaries8.0%41.3%50.7%

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

Local help

Caribou County, Local resources

Radon testing and mitigation in Caribou County

What Idaho's program says
Phone
800-445-8647
Email
radon@dhw.idaho.gov

What it means

Caribou County, Questions

Questions about radon in Caribou County

Are radon levels high in Caribou County?

Over the 2008 to 2017 laboratory totals, 43.9% of the radon tests reported to CDC for Caribou County, Idaho were at or above 4 pCi/L, and the median reported pre-mitigation result was 3.4 pCi/L. Of 37 Idaho counties with 30 or more tests for the same period, 14 reported a higher share; pooled, the state comes to 41.5%.

Which counties border Caribou County?

Caribou County borders 6 counties: Bannock County, ID, Bear Lake County, ID, Franklin County, ID, Bonneville County, ID, Lincoln County, WY and Bingham County, ID.

Products

Caribou County, Products

Testing a home in Caribou County

In Caribou County, 43.9% of 57 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 41.5% pooled across Idaho. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Caribou County; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Caribou County homes, compared

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Caribou County, Bordering counties

Counties bordering Caribou County

Calculated by Radon411

Caribou County, Cities and towns

Cities and towns in Caribou County

The Census Bureau estimates 7,252 residents in Caribou County for July 1, 2025, 239 more than in 2020 (+3.4%). Spread over its land, that is 4.1 people to the square mile. Its largest town, Soda Springs, has 3,165 residents, 43.6% of the total. Together its 3 incorporated places hold 60.9% of those residents; the other 39.1% live outside any of them. CDC's 57 reported tests for 2008 to 2017 work out to 7.9 per 1,000 residents (2025 estimate), close to Idaho's 6.4.

From Soda Springs to Bancroft, CDC publishes no figure by town: each reads Caribou County's.

The cities and towns in Caribou County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Soda Springs3,165+1.6%43.6%
Grace938+1.7%12.9%
Bancroft317+6.4%4.4%

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).

Caribou County, Homes

Homes in Caribou County

Caribou County is a place of houses on their own lots: 81% of its 3,137 homes are detached single-family houses, against 74% across Idaho. The homes are older than Idaho's as a whole: half were built before 1973 (1990 for Idaho), and 34% date from before 1960. Owners live in 82% of the occupied homes (Idaho: 72%), so for most households a test and a fix are their own to order.

Homes in Caribou County, Idaho, 2019 to 2023
HomesCaribou CountyIdaho
Housing units3,137776,683
Detached houses81%74%
In buildings of 5 or more4%9%
Mobile homes12%7%
Built before 196034%18%
Built since 200016%35%
Middle year built19731990
Owner-occupied82%72%

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