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Radon Levels in Bonneville County, Idaho

EPA puts Bonneville County in Zone 2, its middle radon zone, and high results are common there: 40.1% of the 1,117 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

    40.1%

    1.4 pts below ID

    Bonneville
    40.1%
    Idaho
    41.5%

    1,117 tests, 2008 to 2017

  • Median result

    3.4pCi/L

    Below action level

    Bonneville
    3.4 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    1,117

    3rd of 37 by tests

    Bonneville
    1,117
    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

    17 of 37

    Middle half

    Bonneville
    40.1%
    Bear Lake
    78.1%

    By share, of 37 with 30+ tests

Read a result for Bonneville County

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

Interpret this readingWhat a fix costs

The data

Bonneville County, At a glance

Bonneville County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

Bonneville 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 92% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

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

Reported results by concentration band, Bonneville County, 2008 to 2017, laboratory
Under 2 pCi/L: 22%2 to 4 pCi/L: 38%4 pCi/L and above: 40%

Of 1,117 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Bonneville County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L24822.2%
2 to 4 pCi/L42137.7%
4 pCi/L and above44840.1%
What these figures count

These are the 1,117 tests reported to CDC for Bonneville 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

Bonneville County, Compared

Bonneville County radon figures, compared

Calculated by Radon411

In Bonneville County, about 4 in 10 reported tests over the 2008 to 2017 laboratory totals (448 of 1,117) were at or above EPA's action level. Against the national pool of 35.7%, the gap is 4.4 points higher. Across 44 Idaho counties pooled together, 41.5% of tests reached that level, so Bonneville County runs 1.4 points below its state.

Of 7 neighbours with a figure, all 7 reported a larger share at or above 4 pCi/L; the spread is 43.9% (Caribou County) to 68.3% (Lincoln County, WY). By share, Bonneville County is 17th 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 48.8 pCi/L. Below the action level, 248 tests (22.2%) came in under 2 pCi/L, against 31.5% statewide, and 421 tests (37.7%) 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 40.1% share point the same way here. USGS geology rates 92% of the county's land moderate radon potential. CDC also counts 36 tests taken after mitigation in Bonneville County for the same period: tests in homes where a fix was already in.

CDC's ten-year totals for Bonneville County went from 938 tests (2005 to 2014) to 1,117 (2008 to 2017), the share going from 38.6% to 40.1%.

Bonneville County against Idaho, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Bonneville County
Bonneville County1,11740.1%3.4 pCi/LThis county
Idaho, pooled44 counties, pooled12,96141.5%Not pooled+1.4 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−4.4 points
Bear Lake Countyhighest in the state3278.1%7.8 pCi/L+38.0 points
Payette Countylowest in the state614.9%1.5 pCi/L−35.2 points
Lincoln County, WYborders it14268.3%7.8 pCi/L+28.2 points
Jefferson County, IDborders it20767.1%5.7 pCi/L+27.0 points
Madison County, IDborders it31463.7%6.2 pCi/L+23.6 points
Teton County, IDborders it47353.3%4.4 pCi/L+13.2 points
Bingham County, IDborders it44652.0%4.2 pCi/L+11.9 points
Teton County, WYborders it27844.6%3.4 pCi/L+4.5 points
Caribou County, IDborders it5743.9%3.4 pCi/L+3.8 points
Where Bonneville County's reported results fell, 2008 to 2017, laboratory, beside Idaho and the United States
ResultBonneville County testsBonneville County shareIdaho shareU.S. shareAgainst Idaho
Under 2 pCi/L24822.2%31.5%39.6%−9.3 points
2 to 4 pCi/L42137.7%26.9%24.7%+10.8 points
4 pCi/L and above44840.1%41.5%35.7%−1.4 points
Bonneville 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
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
Clearwater County21 of 373330.3%1.8 pCi/L
Gooding County22 of 376728.4%2.4 pCi/L
Bonneville County ten-year laboratory totals, against Idaho's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestIdaho, pooledChange from the row before
2008 to 20171,11740.1%3.4 pCi/L48.8 pCi/L41.5%−0.1 points
2007 to 20161,11940.2%3.4 pCi/L48.8 pCi/L40.8%+0.8 points
2006 to 20151,07339.4%3.4 pCi/L48.8 pCi/L41.3%+0.8 points
2005 to 201493838.6%3.3 pCi/L48.8 pCi/L41.1%First on file

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

Bonneville County, Geology

The ground under Bonneville County

Predicted

Most of the ground under Bonneville County is one class on USGS's geologic map: 92.4% of its land is moderate radon potential, with 7.6% high. The map puts 64.8% of Bonneville County in the area it calls Middle Rocky Mountain province and 24.0% in Eastern Snake river plain and Malheur-Boise-King Section, with 2 smaller areas beside them. USGS gives the first a radon index of 11 and the second 10, both in the moderate band (9 to 11).

USGS's geologic areas under Bonneville County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Middle Rocky Mountain provinceComplexly folded, faulted, and metamorphosed rocks of volcanic origin.Moderate1164.8%
Eastern Snake river plain and Malheur-Boise-King SectionBasalt flows.Moderate1024.0%
Middle Rocky Mts./YellowstoneExtrusive volcanics, rhyolite flows, variable composition.High127.6%
Basin and RangeCenozoic to Paleozoic sedimentary rocks.Moderate113.6%

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

Bonneville County beside the ground around it

Idaho as a whole has more high-potential ground than Bonneville County: 50.7% of its land, against 7.6% here. Of the 7 counties that border it, 4 have more high-potential ground, Madison County the most at 58.1%.

Share of land by USGS radon potential: Bonneville County, the 7 counties bordering it and Idaho
AreaEPA zoneLow potentialModerate potentialHigh potential
Bonneville CountyZone 2None92.4%7.6%
Madison CountyZone 2None41.9%58.1%
Teton CountyZone 2None60.3%39.7%
Caribou CountyZone 2None100%None
Bingham CountyZone 2None100%None
Jefferson CountyZone 2None99.2%0.8%
Teton County, WYZone 1None58.3%41.7%
Lincoln County, WYZone 1None62.5%37.5%
Idaho44 counties, pooled by land areaVaries8.0%41.3%50.7%

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

Local help

Bonneville County, Local resources

Radon testing and mitigation in Bonneville County

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

What it means

Bonneville County, Questions

Questions about radon in Bonneville County

Are radon levels high in Bonneville County?

Over the 2008 to 2017 laboratory totals, 40.1% of the radon tests reported to CDC for Bonneville 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, 16 reported a higher share; pooled, the state comes to 41.5%.

Which counties border Bonneville County?

Bonneville County borders 7 counties: Madison County, ID, Teton County, ID, Caribou County, ID, Bingham County, ID, Jefferson County, ID, Teton County, WY and Lincoln County, WY.

Products

Bonneville County, Products

Testing a home in Bonneville County

In Bonneville County, 40.1% of 1,117 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 Bonneville County; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Bonneville County homes, compared

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Bonneville County, Bordering counties

Counties bordering Bonneville County

Calculated by Radon411

Bonneville County, Cities and towns

Cities and towns in Bonneville County

Bonneville County is growing: the Census Bureau puts it at 135,771 residents on July 1, 2025, up 8.9% from 124,730 in 2020. That works out to 73 people per square mile of land. Idaho Falls alone is home to 71,785 of them, 52.9% of the total. CDC's 1,117 reported tests for 2008 to 2017 work out to 8.2 per 1,000 residents (2025 estimate), close to Idaho's 6.4.

From Idaho Falls to Irwin, CDC publishes no figure by town: each reads Bonneville County's.

The cities and towns in Bonneville County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Idaho Falls71,785+8.9%52.9%
Ammon20,119+12.5%14.8%
Iona3,179+15.6%2.3%
Ucon1,196+2.3%0.9%
Ririeextends beyond Bonneville County711+6.3%Counted whole
Swan Valley321+32.1%0.2%
Irwin302+14.0%0.2%

7 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). A place that extends beyond Bonneville County is counted whole, so it has no share.

Bonneville County, Homes

Homes in Bonneville County

Of Bonneville County's 46,425 homes, 71% are detached houses, against 74% across Idaho; 10% are in buildings of five or more homes. Half of its homes were built before 1985, close to Idaho's 1990: 21% date from before 1960 and 33% from 2000 or later. 72% of occupied homes are lived in by their owner (Idaho: 72%); in the rest a tenant can run a test, but a fix is the landlord's to make.

Homes in Bonneville County, Idaho, 2019 to 2023
HomesBonneville CountyIdaho
Housing units46,425776,683
Detached houses71%74%
In buildings of 5 or more10%9%
Mobile homes5%7%
Built before 196021%18%
Built since 200033%35%
Middle year built19851990
Owner-occupied72%72%

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