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Radon Levels in Kootenai County, Idaho

EPA puts Kootenai County in Zone 1, its highest radon zone, and high results are common there: 61.0% of the 2,955 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

How to test this homeFind a certified tester

  • Share at 4+ pCi/L

    61.0%

    19.5 pts above ID

    Kootenai
    61.0%
    Idaho
    41.5%

    2,955 tests, 2008 to 2017

  • Median result

    6.0pCi/L

    Action level reached

    Kootenai
    6.0 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    2,955

    2nd of 37 by tests

    Kootenai
    2,955
    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

    7 of 37

    Top quarter

    Kootenai
    61.0%
    Bear Lake
    78.1%

    By share, of 37 with 30+ tests

Read a result for Kootenai County

Starts at Kootenai County's median, 6.0 pCi/L

6.0pCi/L

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

EPA’s reading of 6.0 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. Kootenai County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Kootenai County, At a glance

Kootenai County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Kootenai 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 91% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

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

Reported results by concentration band, Kootenai County, 2008 to 2017, laboratory
Under 2 pCi/L: 22%2 to 4 pCi/L: 17%4 pCi/L and above: 61%

Of 2,955 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Kootenai County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L64621.9%
2 to 4 pCi/L50517.1%
4 pCi/L and above1,80461.0%
What these figures count

These are the 2,955 tests reported to CDC for Kootenai 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

Kootenai County, Compared

Kootenai County radon figures, compared

Calculated by Radon411

More than half: 61.0% of the 2,955 radon tests reported to CDC for Kootenai County over the 2008 to 2017 laboratory totals read at least 4 pCi/L. That places it 7th of 37 Idaho counties with 30 or more tests for the same period. That is 19.5 points above the 41.5% pooled from 44 Idaho counties.

The median result, 6.0 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 274.9 pCi/L. The rest split 21.9% under 2 pCi/L and 17.1% from 2 to 4 (Idaho: 31.5% and 26.9%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 61.0% share point the same way here.

1 of its 3 bordering counties with figures ran higher, led by Shoshone County at 63.0%; Bonner County reported 33.0%. 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 Kootenai County went from 2,440 tests (2005 to 2014) to 2,955 (2008 to 2017), the share going from 61.1% to 61.0%.

Nationally, every county with a figure for the same period pools to 35.7%; Kootenai County sits 25.3 points above it. CDC also counts 397 tests taken after mitigation in Kootenai County for the same period: tests in homes where a fix was already in.

Kootenai County against Idaho, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Kootenai County
Kootenai County2,95561.0%6.0 pCi/LThis county
Idaho, pooled44 counties, pooled12,96141.5%Not pooled−19.5 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−25.3 points
Bear Lake Countyhighest in the state3278.1%7.8 pCi/L+17.1 points
Payette Countylowest in the state614.9%1.5 pCi/L−56.1 points
Shoshone County, IDborders it8163.0%5.7 pCi/L+2.0 points
Spokane County, WAborders it3,12541.4%2.9 pCi/L−19.6 points
Bonner County, IDborders it32133.0%2.3 pCi/L−28.0 points
Benewah County, IDborders it2931.0%2.4 pCi/L−30.0 points
Where Kootenai County's reported results fell, 2008 to 2017, laboratory, beside Idaho and the United States
ResultKootenai County testsKootenai County shareIdaho shareU.S. shareAgainst Idaho
Under 2 pCi/L64621.9%31.5%39.6%−9.6 points
2 to 4 pCi/L50517.1%26.9%24.7%−9.8 points
4 pCi/L and above1,80461.0%41.5%35.7%+19.5 points
Kootenai 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
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
Adams County12 of 373151.6%4.0 pCi/L
Kootenai County ten-year laboratory totals, against Idaho's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestIdaho, pooledChange from the row before
2008 to 20172,95561.0%6.0 pCi/L274.9 pCi/L41.5%+0.3 points
2007 to 20162,83460.7%5.9 pCi/L274.9 pCi/L40.8%Level
2006 to 20152,67160.7%5.9 pCi/L274.9 pCi/L41.3%−0.4 points
2005 to 20142,44061.1%6.0 pCi/L274.9 pCi/L41.1%First on file

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

Kootenai County, Geology

The ground under Kootenai County

Predicted

Most of the ground under Kootenai County is one class on USGS's geologic map: 91.5% of its land is high radon potential, with 8.5% moderate. The map puts 91.5% of Kootenai County in the area it calls Northern Rocky Mountain Province and 8.5% in Palouse Hills. 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 Kootenai County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Northern Rocky Mountain ProvinceDiorite and granite of the Idaho batholith.High1291.5%
Palouse HillsBasalt, locally covered by loess.Moderate108.5%

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

Kootenai County beside the ground around it

Kootenai County has more high-potential ground than Idaho as a whole: 91.5% of its land against 50.7%. Of the 4 counties that border it, 2 have more high-potential ground, Shoshone County the most at 100%.

Share of land by USGS radon potential: Kootenai County, the 4 counties bordering it and Idaho
AreaEPA zoneLow potentialModerate potentialHigh potential
Kootenai CountyZone 1None8.5%91.5%
Benewah CountyZone 1None9.6%90.4%
Shoshone CountyZone 1NoneNone100%
Spokane County, WAZone 1None56.7%43.3%
Bonner 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

Kootenai County, Local resources

Radon testing and mitigation in Kootenai County

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

What it means

Kootenai County, Questions

Questions about radon in Kootenai County

Are radon levels high in Kootenai County?

Over the 2008 to 2017 laboratory totals, 61.0% of the radon tests reported to CDC for Kootenai County, Idaho were at or above 4 pCi/L, and the median reported pre-mitigation result was 6.0 pCi/L. Of 37 Idaho counties with 30 or more tests for the same period, 6 reported a higher share; pooled, the state comes to 41.5%.

Which counties border Kootenai County?

Kootenai County borders 4 counties: Benewah County, ID, Shoshone County, ID, Spokane County, WA and Bonner County, ID.

Products

Kootenai County, Products

Testing a home in Kootenai County

In Kootenai County, 61.0% of 2,955 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 Kootenai 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

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

Explore

Kootenai County, Bordering counties

Counties bordering Kootenai County

Calculated by Radon411

Kootenai County, Cities and towns

Cities and towns in Kootenai County

Kootenai County is growing: the Census Bureau puts it at 191,864 residents on July 1, 2025, up 11.0% from 172,797 in 2020. That works out to 155 people per square mile of land. Its largest town, Coeur d'Alene, has 58,179 residents, 30.3% of the total. Together its 14 incorporated places hold 74.8% of those residents; the other 25.2% live outside any of them. Testing is reported here more often than across the state: CDC's 2,955 reported tests for 2008 to 2017 come to 15.4 for every 1,000 residents (2025 estimate), against 6.4 for Idaho.

From Coeur d'Alene to State Line, CDC publishes no figure by town: each reads Kootenai County's.

The 12 largest cities and towns in Kootenai County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Coeur d'Alene58,179+5.9%30.3%
Post Falls46,715+18.8%24.3%
Hayden17,363+10.9%9.0%
Rathdrum13,227+42.4%6.9%
Dalton Gardens2,496−1.7%1.3%
Spirit Lake2,485+5.8%1.3%
Hauser915+19.5%0.5%
Athol738+5.6%0.4%
Hayden Lake668+2.6%0.3%
Worley248−1.6%0.1%
Harrison222−3.9%0.1%
Fernan Lake Village163−3.6%Under 0.1%
  • Huetter
  • State Line

14 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).

Kootenai County, Homes

Homes in Kootenai County

Of Kootenai County's 78,013 homes, 74% are detached houses, against 74% across Idaho; 10% are in buildings of five or more homes. Half of its homes were built before 1995, close to Idaho's 1990: 11% date from before 1960 and 41% 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 Kootenai County, Idaho, 2019 to 2023
HomesKootenai CountyIdaho
Housing units78,013776,683
Detached houses74%74%
In buildings of 5 or more10%9%
Mobile homes8%7%
Built before 196011%18%
Built since 200041%35%
Middle year built19951990
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.