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Radon Levels in Shoshone County, Idaho

EPA puts Shoshone County in Zone 1, its highest radon zone, and high results are common there: 63.0% of the 81 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

    63.0%

    21.5 pts above ID

    Shoshone
    63.0%
    Idaho
    41.5%

    81 tests, 2008 to 2017

  • Median result

    5.7pCi/L

    Action level reached

    Shoshone
    5.7 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    81

    22nd of 37 by tests

    Shoshone
    81
    Ada
    3,030

    Reported to CDC before any fix, 2008 to 2017

  • 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

    6 of 37

    Top quarter

    Shoshone
    63.0%
    Bear Lake
    78.1%

    By share, of 37 with 30+ tests

Read a result for Shoshone County

Starts at Shoshone County's median, 5.7 pCi/L

5.7pCi/L

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

EPA’s reading of 5.7 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. Shoshone County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Shoshone County, At a glance

Shoshone County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Shoshone 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 100% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

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

Reported results by concentration band, Shoshone County, 2008 to 2017, laboratory
Under 2 pCi/L: 22%2 to 4 pCi/L: 15%4 pCi/L and above: 63%

Of 81 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Shoshone County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L1822.2%
2 to 4 pCi/L1214.8%
4 pCi/L and above5163.0%
What these figures count

These are the 81 tests reported to CDC for Shoshone 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

Shoshone County, Compared

Shoshone County radon figures, compared

Calculated by Radon411

More than half: 63.0% of the 81 radon tests reported to CDC for Shoshone County over the 2008 to 2017 laboratory totals read at least 4 pCi/L. That places it 6th of 37 Idaho counties with 30 or more tests for the same period. That is 21.5 points above the 41.5% pooled from 44 Idaho counties.

The median result, 5.7 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 102.9 pCi/L. The rest split 22.2% under 2 pCi/L and 14.8% from 2 to 4 (Idaho: 31.5% and 26.9%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 63.0% share point the same way here.

No bordering county with a figure for the same period reported a higher share; the closest is Kootenai County at 61.0%, the lowest Latah County at 26.0%. Statewide for the same period, Bear Lake County reported the highest share (78.1%) and Payette County the lowest (4.9%).

CDC's ten-year totals for Shoshone County went from 67 tests (2005 to 2014) to 81 (2008 to 2017), the share going from 55.2% to 63.0%.

Nationally, every county with a figure for the same period pools to 35.7%; Shoshone County sits 27.3 points above it. CDC also counts 5 tests taken after mitigation in Shoshone County for the same period: tests in homes where a fix was already in.

Shoshone County against Idaho, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Shoshone County
Shoshone County8163.0%5.7 pCi/LThis county
Idaho, pooled44 counties, pooled12,96141.5%Not pooled−21.5 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−27.3 points
Bear Lake Countyhighest in the state3278.1%7.8 pCi/L+15.1 points
Payette Countylowest in the state614.9%1.5 pCi/L−58.1 points
Kootenai County, IDborders it2,95561.0%6.0 pCi/L−2.0 points
Mineral County, MTborders it3056.7%5.1 pCi/L−6.3 points
Sanders County, MTborders it3850.0%4.0 pCi/L−13.0 points
Bonner County, IDborders it32133.0%2.3 pCi/L−30.0 points
Benewah County, IDborders it2931.0%2.4 pCi/L−32.0 points
Clearwater County, IDborders it3330.3%1.8 pCi/L−32.7 points
Latah County, IDborders it15026.0%1.7 pCi/L−37.0 points
Where Shoshone County's reported results fell, 2008 to 2017, laboratory, beside Idaho and the United States
ResultShoshone County testsShoshone County shareIdaho shareU.S. shareAgainst Idaho
Under 2 pCi/L1822.2%31.5%39.6%−9.3 points
2 to 4 pCi/L1214.8%26.9%24.7%−12.1 points
4 pCi/L and above5163.0%41.5%35.7%+21.5 points
Shoshone 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
Bear Lake County1 of 373278.1%7.8 pCi/L
Custer County2 of 373372.7%6.8 pCi/L
Jefferson County3 of 3720767.1%5.7 pCi/L
Lemhi County4 of 3711265.2%5.2 pCi/L
Madison County5 of 3731463.7%6.2 pCi/L
Shoshone County6 of 378163.0%5.7 pCi/L
Kootenai County7 of 372,95561.0%6.0 pCi/L
Cassia County8 of 3712159.5%5.4 pCi/L
Blaine County9 of 3735257.7%5.3 pCi/L
Teton County10 of 3747353.3%4.4 pCi/L
Bingham County11 of 3744652.0%4.2 pCi/L
Shoshone County ten-year laboratory totals, against Idaho's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestIdaho, pooledChange from the row before
2008 to 20178163.0%5.7 pCi/L102.9 pCi/L41.5%+3.2 points
2007 to 20168759.8%4.5 pCi/L102.9 pCi/L40.8%+1.0 points
2006 to 20158558.8%4.5 pCi/L102.9 pCi/L41.3%+3.6 points
2005 to 20146755.2%4.2 pCi/L102.9 pCi/L41.1%First on file

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

Shoshone County, Geology

The ground under Shoshone County

Predicted

USGS's geologic map puts all of Shoshone County's mapped land in one class: high radon potential. All of it lies in the area the map calls Northern Rocky Mountain Province, to which USGS gives a radon index of 12, in the high band (12 to 17).

USGS's geologic areas under Shoshone County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Northern Rocky Mountain ProvinceDiorite and granite of the Idaho batholith.High1299.8%

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

Shoshone County beside the ground around it

Shoshone County has more high-potential ground than Idaho as a whole: 100% of its land against 50.7%. Of the 7 counties that border it, none has as large a share of high-potential ground; Mineral County, MT comes nearest at 100%.

Share of land by USGS radon potential: Shoshone County, the 7 counties bordering it and Idaho
AreaEPA zoneLow potentialModerate potentialHigh potential
Shoshone CountyZone 1NoneNone100%
Kootenai CountyZone 1None8.5%91.5%
Benewah CountyZone 1None9.6%90.4%
Sanders County, MTZone 1NoneNone100%
Latah CountyZone 131.0%12.1%56.9%
Bonner CountyZone 1NoneNone100%
Mineral County, MTZone 1NoneNone100%
Clearwater CountyZone 118.8%None81.2%
Idaho44 counties, pooled by land areaVaries8.0%41.3%50.7%

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

Local help

Shoshone County, Local resources

Radon testing and mitigation in Shoshone County

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

What it means

Shoshone County, Questions

Questions about radon in Shoshone County

Are radon levels high in Shoshone County?

Over the 2008 to 2017 laboratory totals, 63.0% of the radon tests reported to CDC for Shoshone County, Idaho were at or above 4 pCi/L, and the median reported pre-mitigation result was 5.7 pCi/L. Of 37 Idaho counties with 30 or more tests for the same period, 5 reported a higher share; pooled, the state comes to 41.5%.

Which counties border Shoshone County?

Shoshone County borders 7 counties: Kootenai County, ID, Benewah County, ID, Sanders County, MT, Latah County, ID, Bonner County, ID, Mineral County, MT and Clearwater County, ID.

Products

Shoshone County, Products

Testing a home in Shoshone County

In Shoshone County, 63.0% of 81 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 41.5% pooled across Idaho. In Zone 1 the year-round level in Shoshone 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

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

Explore

Shoshone County, Bordering counties

Counties bordering Shoshone County

Calculated by Radon411

Shoshone County, Cities and towns

Cities and towns in Shoshone County

Shoshone County is growing: the Census Bureau puts it at 14,130 residents on July 1, 2025, up 7.1% from 13,198 in 2020. Spread over its land, that is 5.4 people to the square mile. No town dominates: Kellogg, the largest, has 2,456 residents, 17.4% of the total. Together its 7 incorporated places hold 59.7% of those residents; the other 40.3% live outside any of them. CDC's 81 reported tests for 2008 to 2017 work out to 5.7 per 1,000 residents (2025 estimate), close to Idaho's 6.4.

From Kellogg to Wardner, CDC publishes no figure by town: each reads Shoshone County's.

The cities and towns in Shoshone County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Kellogg2,456+6.0%17.4%
Pinehurst1,780+6.2%12.6%
Osburn1,673+4.7%11.8%
Wallace844+3.6%6.0%
Smelterville813+4.9%5.8%
Mullan663+3.9%4.7%
Wardner205+5.7%1.5%

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).

Shoshone County, Homes

Homes in Shoshone County

Shoshone County is a place of houses on their own lots: 77% of its 7,036 homes are detached single-family houses, against 74% across Idaho. The homes are older than Idaho's as a whole: half were built before 1958 (1990 for Idaho), and 53% date from before 1960. 74% 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 Shoshone County, Idaho, 2019 to 2023
HomesShoshone CountyIdaho
Housing units7,036776,683
Detached houses77%74%
In buildings of 5 or more6%9%
Mobile homes11%7%
Built before 196053%18%
Built since 20006%35%
Middle year built19581990
Owner-occupied74%72%

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