Radon by ZIP

Radon zones in Idaho

Last updated

EPA’s Map of Radon Zones places 44 Idaho counties in its three radon potential zones: 19 in Zone 1 (highest), 20 in Zone 2 (moderate), and 5 in Zone 3 (low).

19Zone 1 · Highest potential
20Zone 2 · Moderate potential
5Zone 3 · Low potential

What this means for Idaho homes

Most Idaho counties fall in Zone 2. EPA predicts moderate average indoor levels (2 to 4 pCi/L) across much of Idaho. Many homes will be below the action level, but many will not, and only a test can tell which.

EPA’s guidance is the same everywhere: test your home, fix it if the level is 4 pCi/L or higher, and consider fixing between 2 and 4 pCi/L. The zone map is from 1993 and should not be used to decide whether a single home needs testing.

Idaho radon program

EPA lists the following state contact for Idaho: ID Department of Health and Welfare Indoor Environment/Radon, phone 208-334-0606. Website: healthandwelfare.idaho.gov/health-wellness/environmental-health/radon. State programs can tell you about local testing data, free or discounted test kits, disclosure rules for home sales, and credentialed radon professionals.

Idaho counties and their EPA radon zones

CountyEPA radon zone
Ada CountyZone 2
Adams CountyZone 3
Bannock CountyZone 2
Bear Lake CountyZone 2
Benewah CountyZone 1
Bingham CountyZone 2
Blaine CountyZone 1
Boise CountyZone 1
Bonner CountyZone 1
Bonneville CountyZone 2
Boundary CountyZone 1
Butte CountyZone 1
Camas CountyZone 1
Canyon CountyZone 2
Caribou CountyZone 2
Cassia CountyZone 2
Clark CountyZone 1
Clearwater CountyZone 1
Custer CountyZone 1
Elmore CountyZone 1
Franklin CountyZone 2
Fremont CountyZone 1
Gem CountyZone 3
Gooding CountyZone 1
Idaho CountyZone 1
Jefferson CountyZone 2
Jerome CountyZone 2
Kootenai CountyZone 1
Latah CountyZone 1
Lemhi CountyZone 1
Lewis CountyZone 3
Lincoln CountyZone 2
Madison CountyZone 2
Minidoka CountyZone 2
Nez Perce CountyZone 3
Oneida CountyZone 2
Owyhee CountyZone 2
Payette CountyZone 2
Power CountyZone 2
Shoshone CountyZone 1
Teton CountyZone 2
Twin Falls CountyZone 2
Valley CountyZone 1
Washington CountyZone 3

County names follow the 2020 Census. Zones from the EPA Map of Radon Zones (text version). Rows marked “zone of” use the zone EPA gave the predecessor or surrounding county.

Next steps: read how to test your home, check a result with the level calculator, or look up a single address by ZIP code.

Sources

  1. U.S. EPA, EPA Map of Radon Zones (text version)
  2. U.S. EPA, EPA Map of Radon Zones and Supplemental Information (state radon contacts)
  3. U.S. EPA, EPA Maps of Radon Zones and Supporting Documents by State