Radon Levels by State

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Introduction

Radon, a radioactive gas, is a significant concern when it comes to indoor air quality. It is produced naturally from the decay of uranium in the soil, and high radon levels can pose health risks, mainly when it accumulates indoors. Certain states in the United States have higher radon levels than others. Alaska and South Dakota have the highest radon levels in the US at 10.7 pCi/L and 9.6 pCi/L, respectively. Pennsylvania, Ohio, and Washington also exhibit relatively high radon levels, ranging from 7.5 pCi/L to 8.6 pCi/L.

States in the northern region, such as Alaska, South Dakota, and Pennsylvania, tend to have higher average radon levels. This could be attributed to geological factors, including the presence of uranium-rich rock formations or soil characteristics. Additionally, states in the Midwest and Mountain regions, like Ohio, Kentucky, and Montana, also exhibit elevated radon levels.

Average Radon Levels by State

#StateRadon Levels
1Alaska10.7 pCi/L
2South Dakota9.6 pCi/L
3Pennsylvania8.6 pCi/L
4Ohio7.8 pCi/L
5Washington7.5 pCi/L
6Kentucky7.4 pCi/L
7Montana7.4 pCi/L
8Idaho7.3 pCi/L
9Colorado6.8 pCi/L
10Iowa6.1 pCi/L
11West Virginia6.1 pCi/L
12North Dakota6 pCi/L
13Maine5.9 pCi/L
14Wisconsin5.7 pCi/L
15New Hampshire5.6 pCi/L
16Maryland5.4 pCi/L
17Illinois5.3 pCi/L
18Nebraska5.2 pCi/L
19Wyoming5 pCi/L
20Kansas4.9 pCi/L
21Tennessee4.8 pCi/L
22Indiana4.7 pCi/L
23Minnesota4.6 pCi/L
24New Jersey4.4 pCi/L
25Utah4.4 pCi/L
26Missouri4.3 pCi/L
27Rhode Island4.3 pCi/L
28New York4.2 pCi/L
29North Carolina4 pCi/L
30Alabama3.9 pCi/L
31Massachusetts3.9 pCi/L
32New Mexico3.9 pCi/L
33Vermont3.7 pCi/L
34Virginia3.6 pCi/L
35Michigan3.5 pCi/L
36Connecticut3.4 pCi/L
37Nevada3.4 pCi/L
38Oregon3.1 pCi/L
39Arkansas2.5 pCi/L
40Oklahoma2.5 pCi/L
41Delaware2.4 pCi/L
42South Carolina2.4 pCi/L
43California2.3 pCi/L
44Georgia2.3 pCi/L
45Texas2.1 pCi/L
46Arizona1.9 pCi/L
47Florida1.8 pCi/L
48Mississippi1.2 pCi/L
49Louisiana1.1 pCi/L
50Hawaii0 pCi/L

States With Highest Radon Levels

The ten states with the highest radon levels are Alaska, South Dakota, Pennsylvania, Ohio, Washington, Kentucky, Montana, Idaho, Colorado, and Iowa. Alaska is the state with the highest radon levels in the US with 10.7 pCi/L. South Dakota is the second state with the highest radon levels with 9.6 pCi/L. Pennsylvania has the third highest radon levels with 8.6 pCi/L, while Ohio and Washington have radon levels of 7.8 pCi/L and 7.5 pCi/L, respectively. Kentucky and Montana share a radon level of 7.4 pCi/L, and Idaho follows closely with 7.3 pCi/L. Colorado is the ninth state with the highest radon levels with 6.8 pCi/L, and Iowa is the tenth state with the highest radon levels with 6.1 pCi/L.

The top ten states with the highest radon levels are:

1. Alaska – 10.7 pCi/L
2. South Dakota – 9.6 pCi/L
3. Pennsylvania – 8.6 pCi/L
4. Ohio – 7.8 pCi/L
5. Washington – 7.5 pCi/L
6. Kentucky – 7.4 pCi/L
7. Montana – 7.4 pCi/L
8. Idaho – 7.3 pCi/L
9. Colorado – 6.8 pCi/L
10. Iowa – 6.1 pCi/L

Radon Levels by State

Alabama

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3.9 pCi/L

Ranked in the US

#30

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Alaska

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10.7 pCi/L

Ranked in the US

#1

Alaska has the highest radon levels in the US with 10.7 pCi/L. The state's geological composition, including uranium-rich rock formations and extensive granite deposits, contributes to the elevated radon levels.

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Arizona

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1.9 pCi/L

Ranked in the US

#46

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Arkansas

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2.5 pCi/L

Ranked in the US

#39

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California

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2.3 pCi/L

Ranked in the US

#43

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Colorado

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6.8 pCi/L

Ranked in the US

#9

Colorado has the ninth highest radon levels in the US with 6.8 pCi/L. The state's elevated radon levels are influenced by its geology, which includes a significant amount of uranium-rich rocks like granite and shale.

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Connecticut

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3.4 pCi/L

Ranked in the US

#36

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Delaware

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2.4 pCi/L

Ranked in the US

#41

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Florida

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1.8 pCi/L

Ranked in the US

#47

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Georgia

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2.3 pCi/L

Ranked in the US

#44

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Hawaii

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0 pCi/L

Ranked in the US

#50

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Idaho

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7.3 pCi/L

Ranked in the US

#8

Idaho has the eighth highest radon levels in the US with 7.3 pCi/L. The state's high radon levels are primarily due to its geology, as Idaho has abundant granite and volcanic rock formations that contain uranium, leading to increased radon gas levels.

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Illinois

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5.3 pCi/L

Ranked in the US

#17

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Indiana

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4.7 pCi/L

Ranked in the US

#22

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Iowa

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6.1 pCi/L

Ranked in the US

#10

Iowa has the tenth highest radon levels in the US with 6.1 pCi/L. The state's radon levels are primarily attributed to its geology, as Iowa has high concentrations of uranium-rich glacial deposits and sedimentary rocks that contribute to the release of radon gas.

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Kansas

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4.9 pCi/L

Ranked in the US

#20

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Kentucky

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7.4 pCi/L

Ranked in the US

#6

Kentucky has the sixth highest radon levels in the US with 7.4 pCi/L. The state's high radon levels can be attributed to its geological composition, which includes soils and rock formations rich in uranium. Kentucky also has a long history of coal mining, and the presence of coal deposits and associated rocks can release radon gas into the surrounding environment.

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Louisiana

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1.1 pCi/L

Ranked in the US

#49

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Maine

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5.9 pCi/L

Ranked in the US

#13

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Maryland

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5.4 pCi/L

Ranked in the US

#16

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Massachusetts

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3.9 pCi/L

Ranked in the US

#31

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Michigan

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3.5 pCi/L

Ranked in the US

#35

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Minnesota

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4.6 pCi/L

Ranked in the US

#23

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Mississippi

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1.2 pCi/L

Ranked in the US

#48

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Missouri

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4.3 pCi/L

Ranked in the US

#26

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Montana

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7.4 pCi/L

Ranked in the US

#7

Montana also has the sixth highest radon levels in the US with 7.4 pCi/L. The state's radon levels are primarily influenced by its geology, which includes rocks such as granite and shale that contain uranium. Montana's mountainous terrain and geological diversity contribute to the presence of uranium-rich formations, increasing the likelihood of elevated radon levels.

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Nebraska

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5.2 pCi/L

Ranked in the US

#18

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Nevada

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3.4 pCi/L

Ranked in the US

#37

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New Hampshire

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5.6 pCi/L

Ranked in the US

#15

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New Jersey

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4.4 pCi/L

Ranked in the US

#24

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New Mexico

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3.9 pCi/L

Ranked in the US

#32

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New York

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4.2 pCi/L

Ranked in the US

#28

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North Carolina

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4 pCi/L

Ranked in the US

#29

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North Dakota

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6 pCi/L

Ranked in the US

#12

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Ohio

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7.8 pCi/L

Ranked in the US

#4

Ohio has the fourth highest radon levels in the US with 7.8 pCi/L. The state's high radon levels are linked to its geology, specifically the prevalence of glacial deposits that contain radon-producing minerals like uranium and thorium.

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Oklahoma

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2.5 pCi/L

Ranked in the US

#40

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Oregon

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3.1 pCi/L

Ranked in the US

#38

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Pennsylvania

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8.6 pCi/L

Ranked in the US

#3

Pennsylvania has the third highest radon levels in the US with 8.6 pCi/L. The state's radon levels are elevated due to its geology, specifically the presence of uranium and radium in the bedrock, which results in the release of radon gas into the soil and subsequently into homes and structures.

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Rhode Island

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4.3 pCi/L

Ranked in the US

#27

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South Carolina

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2.4 pCi/L

Ranked in the US

#42

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South Dakota

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9.6 pCi/L

Ranked in the US

#2

South Dakota holds the second highest radon levels with 9.6 pCi/L. The state's geology, characterized by granite and shale formations, plays a significant role in the high radon concentrations found in homes and buildings.

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Tennessee

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4.8 pCi/L

Ranked in the US

#21

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Texas

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2.1 pCi/L

Ranked in the US

#45

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Utah

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4.4 pCi/L

Ranked in the US

#25

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Vermont

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3.7 pCi/L

Ranked in the US

#33

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Virginia

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3.6 pCi/L

Ranked in the US

#34

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Washington

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7.5 pCi/L

Ranked in the US

#5

Washington has the fifth highest radon levels in the US with 7.5 pCi/L. The state's radon levels can be attributed to its diverse geology, including granitic rocks, which can release radon gas as they naturally decay over time.

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West Virginia

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6.1 pCi/L

Ranked in the US

#11

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Wisconsin

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5.7 pCi/L

Ranked in the US

#14

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Wyoming

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5 pCi/L

Ranked in the US

#19

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