EPA radon zones
Montana radon map: every county's zone
50 of Montana's 57 counties are EPA radon zone 1 (predicted average above 4 pCi/L), 7 are zone 2 and 0 are zone 3. High readings occur in every zone, so EPA recommends testing every home.
Beaverhead CountyZone 1
Big Horn CountyZone 1
Blaine CountyZone 1
Broadwater CountyZone 1
Carbon CountyZone 1
Carter CountyZone 1
Cascade CountyZone 1
Chouteau CountyZone 1
Custer CountyZone 1
Daniels CountyZone 1
Dawson CountyZone 1
Deer Lodge CountyZone 1
Fallon CountyZone 1
Fergus CountyZone 1
Flathead CountyZone 1
Gallatin CountyZone 1
Garfield CountyZone 1
Glacier CountyZone 1
Golden Valley CountyZone 2
Granite CountyZone 1
Hill CountyZone 1
Jefferson CountyZone 1
Judith Basin CountyZone 1
Lake CountyZone 1
Lewis and Clark CountyZone 1
Liberty CountyZone 1
Lincoln CountyZone 1
Madison CountyZone 1
McCone CountyZone 1
Meagher CountyZone 1
Mineral CountyZone 1
Missoula CountyZone 1
Musselshell CountyZone 2
Park CountyZone 1
Petroleum CountyZone 2
Phillips CountyZone 1
Pondera CountyZone 1
Powder River CountyZone 1
Powell CountyZone 1
Prairie CountyZone 1
Ravalli CountyZone 1
Richland CountyZone 1
Roosevelt CountyZone 1
Rosebud CountyZone 1
Sanders CountyZone 1
Sheridan CountyZone 1
Silver Bow CountyZone 1
Stillwater CountyZone 1
Sweet Grass CountyZone 2
Teton CountyZone 1
Toole CountyZone 1
Treasure CountyZone 2
Valley CountyZone 1
Wheatland CountyZone 2
Wibaux CountyZone 1
Yellowstone CountyZone 2
Yellowstone National Park, MTZone 1
How much does radon mitigation cost?
Most single-family systems cost $800 to $2,500 installed, depending on foundation type and how many suction points are needed. A follow-up test confirms the system works.
What do the zones mean?
EPA radon zones describe counties, not houses. Zone 1 counties have a predicted average indoor level above 4 picocuries per liter (pCi/L), Zone 2 between 2 and 4, Zone 3 below 2. Homes with high levels are found in every zone, which is why EPA recommends that every home be tested, and fixed at 4 pCi/L or above.
Source: EPA Map of Radon Zones.