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Florida Statewide Radiation Study



It has been known since the early part of this century that Florida phosphate deposits contained higher levels of uranium than did most other soils and rocks. During the 1970’s two independent studies confirmed that some citizens of the phosphate regions were exposed to higher than desirable levels of uranium decay products, mainly radon and its short-lived daughters. In 1986 the Florida Legislature directed the Florida Institute of Phosphate Research to conduct a statewide survey to determine all significant land areas of the state where an environmental radiation standard should be applied. The study was designed to assess six types of data, including indoor radon in over 6,000 homes, soil radon at 3,000 homes, and all data existing prior to the study. At the close of the study it was possible to designate by county and by U.S.G.S. quadrangle some 7% of the state having definite evidence of elevated radon potential. This report explains the purpose of the study, how it was designed and conducted, and what results were found. It concludes with a discussion of the radon/radon decay product equilibrium factor, a discussion of the correlation between indoor and soil radon, and preliminary attempts to develop a “safe” threshold for soil radon below which few elevated indoor levels would be anticipated.