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Radon Levels in Butte County, Idaho

EPA puts Butte County in Zone 1, its highest radon zone, and only 29 radon tests from it are on file with CDC (2008 to 2017, laboratory totals). 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

    74.2%

    33.4 pts above ID

    Butte
    74.2%
    Idaho
    40.8%

    31 tests, 2007 to 2016

  • Median result

    13.0pCi/L

    Action level reached

    Butte
    13.0 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2007 to 2016

  • Tests reported

    31

    39th of 40 by tests

    Butte
    31
    Ada
    2,966

    Reported to CDC before any fix, 2007 to 2016

  • EPA radon zone

    Zone 1

    Highest potential

    1. Zone 1
    2. 2
    3. 3

    1 highest, 3 lowest

    EPA predicts over 4 pCi/L indoors

  • Rank in Idaho

    2 of 40

    Top quarter

    Butte
    74.2%
    Bear Lake
    78.1%

    By share, of 40 with 30+ tests

Read a result for Butte County

Starts at Butte County's median, 13.0 pCi/L

13.0pCi/L

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

EPA’s reading of 13.0 pCi/L

At or above 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 at or above 4 pCi/L. EPA recommends fixing a home when the radon level is 4 pCi/L or higher. Butte County's median reported result, 2007 to 2016.

Interpret this readingWhat a fix costs

The data

Butte County, At a glance

Butte County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Butte County in and predicts an average indoor of greater than 4 pCi/L (greater than 150 Bq/m³) across the county. That is one forecast for the whole county, not a reading of any address in it; homes above EPA's turn up in all three zones.

USGS geologic potential: High across 53% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

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

CDC holds 29 reported tests for Butte County over the 2008 to 2017 laboratory totals, with a median of 12.8 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Butte County beside the counties around it is how this page reads it.

What these figures count

Only 29 tests were reported to CDC for Butte County over 2008 to 2017 (laboratory totals), and tests are often run on homes being sold or already suspected of a problem: so few describe neither the county nor 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

Butte County, Compared

Butte County radon figures, compared

Calculated by Radon411

More than half: 74.2% of the 31 radon tests reported to CDC for Butte County over the 2007 to 2016 laboratory totals read at least 4 pCi/L. That places it 2nd of 40 Idaho counties with 30 or more tests for the same period. That is 33.4 points above the 40.8% pooled from 44 Idaho counties.

The newest figure, over the 2008 to 2017 laboratory totals, counts only 29 tests (75.9% at or above 4 pCi/L), too few to compare, so this reading uses the 31-test figure.

The median result, 13.0 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 93.9 pCi/L. The rest split 9.7% under 2 pCi/L and 16.1% from 2 to 4 (Idaho: 32.2% and 27.0%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 74.2% share point the same way here.

No bordering county with a figure for the same period reported a higher share; the closest is Custer County at 73.7%, the lowest Bingham County at 51.2%. Statewide for the same period, Bear Lake County reported the highest share (78.1%) and Payette County the lowest (5.5%).

CDC's ten-year totals for Butte County went from 29 tests (2005 to 2014) to 29 (2008 to 2017), the share going from 75.9% to 75.9%.

Nationally, every county with a figure for the same period pools to 35.8%; Butte County sits 38.4 points above it.

Butte County against Idaho, the United States and nearby counties, 2007 to 2016, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Butte County
Butte County3174.2%13.0 pCi/LThis county
Idaho, pooled44 counties, pooled12,49540.8%Not pooled−33.4 points
United States, pooled2,666 counties, pooled1,939,02535.8%Not pooled−38.4 points
Bear Lake Countyhighest in the state3278.1%6.5 pCi/L+3.9 points
Payette Countylowest in the state555.5%1.3 pCi/L−68.7 points
Clark County, IDborders it475.0%14.1 pCi/L+0.8 points
Custer County, IDborders it3873.7%6.8 pCi/L−0.5 points
Jefferson County, IDborders it18763.6%5.3 pCi/L−10.6 points
Lemhi County, IDborders it15360.8%5.1 pCi/L−13.4 points
Blaine County, IDborders it32653.4%4.4 pCi/L−20.8 points
Bingham County, IDborders it45151.2%4.2 pCi/L−23.0 points
Where Butte County's reported results fell, 2007 to 2016, laboratory, beside Idaho and the United States
ResultButte County testsButte County shareIdaho shareU.S. shareAgainst Idaho
Under 2 pCi/L39.7%32.2%39.6%−22.5 points
2 to 4 pCi/L516.1%27.0%24.6%−10.9 points
4 pCi/L and above2374.2%40.8%35.8%+33.4 points
Butte County ranked among the 40 Idaho counties with 30 or more tests, by share at or above 4 pCi/L, 2007 to 2016, laboratory
CountyRankTestsAt or above 4 pCi/LMedian
Bear Lake County1 of 403278.1%6.5 pCi/L
Butte County2 of 403174.2%13.0 pCi/L
Oneida County2 of 403174.2%6.5 pCi/L
Custer County4 of 403873.7%6.8 pCi/L
Madison County5 of 4027965.6%6.5 pCi/L
Jefferson County6 of 4018763.6%5.3 pCi/L
Cassia County7 of 409662.5%5.8 pCi/L
Lemhi County8 of 4015360.8%5.1 pCi/L
Kootenai County9 of 402,83460.7%5.9 pCi/L
Shoshone County10 of 408759.8%4.5 pCi/L
Blaine County11 of 4032653.4%4.4 pCi/L
Butte County ten-year laboratory totals, against Idaho's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestIdaho, pooledChange from the row before
2008 to 20172975.9%12.8 pCi/L89.8 pCi/L41.5%+1.7 points
2007 to 20163174.2%13.0 pCi/L93.9 pCi/L40.8%−3.2 points
2006 to 20153177.4%13.2 pCi/L93.9 pCi/L41.3%+1.5 points
2005 to 20142975.9%13.0 pCi/L93.9 pCi/L41.1%First on file

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

Butte County, Geology

The ground under Butte County

Predicted

USGS's geologic map splits Butte County: 53.1% of its land is high radon potential and 46.9% moderate. The map puts 53.1% of Butte County in the area it calls Northern Rocky Mountain Province and 46.9% in Eastern Snake river plain and Malheur-Boise-King Section. USGS gives the first a radon index of 12, in the high band (12 to 17), and the second 10, in the moderate band (9 to 11).

USGS's geologic areas under Butte County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Northern Rocky Mountain ProvinceDiorite and granite of the Idaho batholith.High1253.1%
Eastern Snake river plain and Malheur-Boise-King SectionBasalt flows.Moderate1046.9%

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

Butte County beside the ground around it

On high-potential ground Butte County is close to Idaho as a whole: 53.1% of its land against 50.7%. Of the 6 counties that border it, 4 have more high-potential ground, Custer County the most at 100%.

Share of land by USGS radon potential: Butte County, the 6 counties bordering it and Idaho
AreaEPA zoneLow potentialModerate potentialHigh potential
Butte CountyZone 1None46.9%53.1%
Jefferson CountyZone 2None99.2%0.8%
Blaine CountyZone 1None36.8%63.2%
Clark CountyZone 1None33.3%66.7%
Bingham CountyZone 2None100%None
Custer CountyZone 1NoneNone100%
Lemhi CountyZone 1NoneNone100%
Idaho44 counties, pooled by land areaVaries8.0%41.3%50.7%

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

Local help

Butte County, Local resources

Radon testing and mitigation in Butte County

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

What it means

Butte County, Questions

Questions about radon in Butte County

Are radon levels high in Butte County?

Over the 2008 to 2017 laboratory totals, 75.9% of the radon tests reported to CDC for Butte County, Idaho were at or above 4 pCi/L, and the median reported pre-mitigation result was 12.8 pCi/L. Of 40 Idaho counties with 30 or more tests for the same period, 1 reported a higher share; pooled, the state comes to 40.8%.

Which counties border Butte County?

Butte County borders 6 counties: Jefferson County, Blaine County, Clark County, Bingham County, Custer County and Lemhi County.

Products

Butte County, Products

Testing a home in Butte County

In Butte County, 74.2% of 31 tests reported to CDC over the 2007 to 2016 laboratory totals reached 4 pCi/L, against 40.8% pooled across Idaho. In Zone 1 the year-round level in Butte County is the one to know: a long-term test (more than 90 days) or a monitor, with a short-term kit for a first answer.

Test kits and monitors3

See every kit and monitor

Butte County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Butte County

Explore

Butte County, Bordering counties

Counties bordering Butte County

Calculated by Radon411

Butte County, Cities and towns

Cities and towns in Butte County

Butte County is growing: the Census Bureau puts it at 2,783 residents on July 1, 2025, up 7.8% from 2,581 in 2020. Spread over its land, that is 1.2 people to the square mile. Its largest town, Arco, has 918 residents, 33.0% of the total. Together its 3 incorporated places hold 42.4% of those residents; the other 57.6% live outside any of them. Testing is reported here more often than across the state: CDC's 31 reported tests for 2007 to 2016 come to 11.1 for every 1,000 residents (2025 estimate), against 6.2 for Idaho.

From Arco to Butte City, CDC publishes no figure by town: each reads Butte County's.

The cities and towns in Butte County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Arco918+4.6%33.0%
Moore176+10.0%6.3%
Butte City87+8.8%3.1%

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).

Butte County, Homes

Homes in Butte County

Of Butte County's 1,275 homes, 71% are detached houses, against 74% across Idaho; 19% are mobile homes. The homes are older than Idaho's as a whole: half were built before 1971 (1990 for Idaho), and 38% date from before 1960. Owners live in 77% of the occupied homes (Idaho: 72%), so for most households a test and a fix are their own to order.

Homes in Butte County, Idaho, 2019 to 2023
HomesButte CountyIdaho
Housing units1,275776,683
Detached houses71%74%
In buildings of 5 or more3%9%
Mobile homes19%7%
Built before 196038%18%
Built since 20007%35%
Middle year built19711990
Owner-occupied77%72%

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