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Abstract: Radon in the Gulf Coast Area: Potential Problem or Exaggerated Risk?

Timothy W. Duex

Indoor air pollution from radon has been identified by the EPA as a serious health problem; estimates indicate that radon is the second leading cause of lung cancer (after smoking) and that high levels of radon may cause as many as 20,000 to 40,000 lung cancer deaths per year in the United States. Studies of the potential risk in the Gulf Coast have been sparse. This report summarizes over 7000 previously unreported radon analyses and relates them to geological information to identify possible problem areas for the Gulf Coast region of Louisiana, Texas, Mississippi, Alabama, and Florida.

High levels of indoor radon are generally associated with older "crystalline" igneous and metamorphic bedrock; thus, most areas of the Gulf Coast are of relatively low risk because they are underlain by Cenozoic sedimentary rocks and unconsolidated deposits. However, some types of sedimentary deposits, such as "black shale" and phosphate-rich rocks, can underlie areas of high risk. According to EPA indoor radon survey results the percentage of houses with screening levels greater than 4 pCi/l (picocuries per liter) for given states is as follows: Alabama = 0.6%, Louisiana = 0.8%, Mississippi = 2.0%, and Texas = 4.0% (no data available for Florida). The data presented here for the percentage of houses with greater than 4 pCi/l for given states is as follows: Alabama = 6.1%, Louisiana = 0.6%, Mississippi = 2.0%, Texas = 1.6%, and Florida = 4.5%. The areas that appear to have the greatest risk are parts of northern Alabama and Mississippi, central Texas, and some areas in Florida.

AAPG Search and Discovery Article #90983©1994 GCAGS and Gulf Coast SEPM 44th Annual Meeting, Austin, Texas, October 6-7, 1994