Radon is a naturally occurring radioactive gas that is odorless, tasteless and colorless. It is formed by the natural radioactive decay of uranium in rock, soil, and water.
Radon is the second-leading cause of lung cancer, costing the United States over $2 billion per year in both direct and indirect health care costs. Radon has no immediate symptoms that will alert someone of its presence and it takes years of exposure before any problems become apparent.
According to the US EPA, nearly 1in 3 homes checked in seven states had radon levels over the recommended action level for radon exposure of 4 pCi/L. The pCi in “pCi/L” is a picocurie, which is one-trillionth of a curie and is the measure of the rate of radioactive decay of radon. At 4 pCi/L, there will be approximately 12,672 disintegrations in one liter of air during a 24-hour period.
According to Air Chek, Inc., 31 states have radon exposure above 4 pCi/L. In general, these states are in the northern half of the United States. Only five states and the District of Columbia are considered to have low radon levels. Those states are:
- Arizona
- Florida
- District of Columbia
- Mississippi
- Louisiana
- Hawaii
Hawaii has the lowest radon levels of all 50 states with an average level of 0 pCi/L. The uranium content of Hawaiian rocks is low and most rocks near the surface are porous, allowing for air infiltration to dilute radon.
The ten states with the highest levels of radon are:
- Alaska
- South Dakota
- Pennsylvania
- Ohio
- Washington
- Montana
- Kentucky
- Idaho
- Colorado
- West Virginia
Alaska has the highest radon levels of 10.7 pCi/L. Homeowners in Alaska are encouraged to test for radon every two years.
Below is a table with each state’s average levels of radon.