Radon Levels by State 2025

Alaska
10.7
South Dakota
9.6
Pennsylvania
8.6
Ohio
7.8
Washington
7.5
Kentucky
7.4
Montana
7.4
Idaho
7.3
Colorado
6.8
Iowa
6.1
West Virginia
6.1
North Dakota
6.0
Maine
5.9
Wisconsin
5.7
New Hampshire
5.6
Maryland
5.4
Illinois
5.3
Nebraska
5.2
Wyoming
5.0
Kansas
4.9
Tennessee
4.8
Indiana
4.7
Minnesota
4.6
New Jersey
4.4
Utah
4.4
Missouri
4.3
Rhode Island
4.3
New York
4.2
North Carolina
4.0
Alabama
3.9
Massachusetts
3.9
New Mexico
3.9
Vermont
3.7
Virginia
3.6
Michigan
3.5
Connecticut
3.4
Nevada
3.4
Oregon
3.1
Arkansas
2.5
Oklahoma
2.5
Delaware
2.4
South Carolina
2.4
California
2.3
Georgia
2.3
Texas
2.1
Arizona
1.9
Florida
1.8
District of Columbia
1.6
Mississippi
1.2
Louisiana
1.1
  • Radon levels shown are state-level averages. Within each state, the radon level can vary significantly from one county, municipality, or home site to another.
  • Radon levels are measured in picocuries per liter (pCi/L). One pCi/L represents one trillionth of a curie of radioactivity per liter of air.