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Idaho Radon Map and Levels by County

Idaho's counties span all three EPA radon zones. 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

    41.5%

    5.8 pts above U.S.

    Idaho
    41.5%
    U.S.
    35.7%

    12,961 tests across 44 counties, 2008 to 2017

  • Rank among states

    15 of 47

    Middle of the states

    Idaho
    41.5%
    North Dakota
    59.3%

    By share, every state pooled the same way, 2008 to 2017

  • Counties in EPA Zone 1

    19 of 44

    Some at highest potential

    Zone 1
    19
    Zone 2
    20

    Most counties sit in Zone 2; Zone 1 is the highest potential

  • Highest county

    78.1%

    Bear Lake County

    Bear Lake
    78.1%
    Payette
    4.9%

    Counties with 30+ tests, 2008 to 2017

Read a result for Idaho

Starts at EPA's action level

4.0pCi/L

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

EPA’s reading of 4.0 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. 41.5% of Idaho's reported tests reached 4 pCi/L, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Idaho, At a glance

Idaho at a glance

Predicted: EPA radon zone

44 of 44 counties classified

EPA classifies counties, not states. Of the 44 counties in Idaho with a zone, 19 are in Zone 1, 20 in Zone 2 and 5 in Zone 3.

  • Zone 1: Highest predicted potentialgreater than 4 pCi/L19 of 44 counties · 43.2%
  • Zone 2: Moderate predicted potential2 to 4 pCi/L20 of 44 counties · 45.5%
  • Zone 3: Lower predicted potentialless than 2 pCi/L5 of 44 counties · 11.4%

An EPA radon zone predicts a whole county. It is not intended to determine whether any individual home should be tested: homes with elevated levels occur in all three zones, and EPA recommends testing every home regardless of zone.

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

CDC test figures, county by county

CDC publishes Idaho's radon test figures by county: 44 of its 44 counties have one. Each one's share is in the county list.

How to read these figures

Idaho, Compared

Idaho radon figures, compared

Calculated by Radon411
Idaho, 2008 to 2017, laboratory
41.5%
of 12,961 tests at or above 4 pCi/L, pooled
Against the U.S.
+5.8points
35.7% pooled
Rank among the states
15 of 47
1 is the highest share
Counties with 30 or more tests
37
Highest
78.1%
Bear Lake County
Lowest
4.9%
Payette County

Idaho pools to 41.5%: that share of 12,961 reported tests from 44 counties over the 2008 to 2017 laboratory totals reached EPA's action level. Nationally the pooled share is 35.7%: 5.8 points lower than here.

Among 47 states pooled the same way it ranks 15th, with Pennsylvania (41.7%) above it and Indiana (38.9%) below. Bear Lake County reports the highest share (78.1% of 32 tests) and Payette County the lowest (4.9%); the most tests came from Ada County, 3,030 of them at 25.2%.

Across its 4 overlapping ten-year totals, the share went from 41.1% (2005 to 2014) to 41.5% (2008 to 2017), within 2 points, with 2008 to 2017 the highest at 41.5%. By band, 12 counties at 50% or more, 9 counties at 30% to 50%, 14 counties at 15% to 30%, 1 county at 5% to 15%, 1 county at under 5%.

EPA's 1993 map puts 19 of its 44 classified counties in Zone 1; against that, 41.5% of the tests reported since reached 4 pCi/L.

Idaho ranked among 47 states by pooled share of tests at or above 4 pCi/L, 2008 to 2017, laboratory
StateRankCountiesTestsAt or above 4 pCi/L
Kentucky10 of 4712028,79343.7%
Minnesota11 of 4787130,91243.4%
Illinois12 of 47102108,90943.1%
Utah13 of 472828,34241.9%
Pennsylvania14 of 4767203,04541.7%
Idaho15 of 474412,96141.5%
Indiana16 of 479243,14838.9%
Maine17 of 471611,82537.6%
West Virginia18 of 475510,06137.5%
New Hampshire19 of 471015,60835.0%
Tennessee20 of 479531,06633.3%
Idaho's highest and lowest counties with 30 or more tests, by share at or above 4 pCi/L, 2008 to 2017, laboratory
CountyRankTestsAt or above 4 pCi/L
Bear Lake County1 of 373278.1%
Custer County2 of 373372.7%
Jefferson County3 of 3720767.1%
Lemhi County4 of 3711265.2%
Madison County5 of 3731463.7%
Shoshone County6 of 378163.0%
Kootenai County7 of 372,95561.0%
Cassia County8 of 3712159.5%
Blaine County9 of 3735257.7%
Teton County10 of 3747353.3%
Payette County37 of 37614.9%
Canyon County36 of 3756310.7%
Minidoka County35 of 377215.3%
Jerome County34 of 376516.9%
Boundary County33 of 374520.0%
Idaho's counties with 30 or more tests, by their own share at or above 4 pCi/L, 2008 to 2017, laboratory
ShareCountiesTheir testsFor example
50% or more125,157Bear Lake County, Custer County, Jefferson County
30% to 50%92,684Fremont County, Elmore County, Caribou County
15% to 30%144,370Gooding County, Valley County, Power County
5% to 15%1563Canyon County
Under 5%161Payette County
Idaho ten-year laboratory totals, pooled, against the United States
PeriodCountiesTestsAt or above 4 pCi/LUnited StatesChange from the row before
2008 to 20174412,96141.5%35.7%+0.7 points
2007 to 20164412,49540.8%35.8%−0.5 points
2006 to 20154411,52141.3%36.3%+0.2 points
2005 to 20144410,34641.1%36.0%First on file

Pooled shares: Radon411's sum of CDC's county counts for one period. CDC publishes no state or national figure.

Idaho, Counties

Idaho counties by EPA zone

Predicted

The map of Idaho, then its 44 counties zone by zone, each with its reported share at or above 4 pCi/L and a report of its own.

Idaho radon map by county: EPA radon zones. Map of Idaho's 44 counties shaded by EPA radon zone: Zone 1 in red-orange, Zone 2 in amber, Zone 3 in pale sand. 19 in Zone 1, 20 in Zone 2, 5 in Zone 3.
Idaho radon map by countyEPA radon zones for Idaho's counties: 19 counties in Zone 1, 20 counties in Zone 2, 5 counties in Zone 3.A prediction for each county, not a reading of any home; elevated homes occur in all three zones.

The 12 highest in Idaho, 2008 to 2017

Zone 1: highest predicted potential19

Local help

Idaho, Local resources

Local resources in Idaho

Who to ask in Idaho: its radon program, test kits and professionals.

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

What it means

Idaho, Questions

Questions about radon in Idaho

Is radon a problem in Idaho?

Idaho has 44 counties on EPA's Map of Radon Zones: Zone 1, the highest predicted potential, for 19; Zone 2 for 20; Zone 3 for 5. Pooled from 44 counties, 41.5% of the 12,961 radon tests reported to CDC over the 2008 to 2017 laboratory totals were at or above 4 pCi/L, 15th of 47 states.

Which Idaho counties are in EPA radon Zone 1?

Zone 1 holds 19 counties in Idaho; the first 8 by name are Benewah County, Blaine County, Boise County, Bonner County, Boundary County, Butte County, Camas County, Clark County, the rest in the county table on this page.

Which Idaho counties have the highest radon?

Bear Lake County 78.1% (32 tests) leads Idaho by the share of reported tests at or above 4 pCi/L, 2008 to 2017, laboratory, then Custer County 72.7% (33 tests), Jefferson County 67.1% (207 tests), Lemhi County 65.2% (112 tests), Madison County 63.7% (314 tests).

Which EPA region is Idaho in?

Idaho is in EPA Region 10: Pacific Northwest.

Products

Idaho, Products

Testing a home in Idaho

41.5% of the 12,961 tests reported to CDC for Idaho over the 2008 to 2017 laboratory totals reached 4 pCi/L: a short-term kit (2 to 90 days) gives a first answer in days, a long-term test the year-round average. A short-term kit (2 to 90 days) is the quick first check for a home in Idaho; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Idaho homes, compared

Explore

Cities in Idaho with their own page

Radon data is published by county, not by city. Each city page sets the figures of the counties the city lies in side by side.