USING GEOLOGY TO PREDICT AND COMMUNICATE RADON POTENTIAL IN KENTUCKY

A team of nurses, health educators, statisticians, and geologists collaborated to create a statewide radon-potential map of Kentucky by intersecting residential radon test kit results (N = 70,000) with a statewide 1:24,000-scale bedrock geology coverage. Radon potential in the United States, Kentucky in particular, has historically been communicated using a single hazard level for each county; however, physical phenomena are not controlled by administrative boundaries, and single-value county maps do not reflect the significant variations in radon potential in each county. We took a more sophisticated, and we think more realistic, approach that uses bedrock geology as a predictive tool. Statistically valid radon-potential estimates for each geologic unit were created by assessing the distribution of test-kit results for each geologic map unit and then using the third quartile value to represent the indoor radon potential for that unit. Spatial variability within units, differences in variability among units, and topographic factors were not explicitly considered, but may be fruitful topics for further research. Although the test-kit results were quantitative, with measurements given in picocuries per liter for consistency with regulatory thresholds in the United States, versions of county radon-potential maps distributed to the public conveyed the radon hazard using qualitative terms of high, medium, or low danger. This mapping project revealed that areas in central and south-central Kentucky with the highest radon potential are underlain by shales and karstic limestones.