In 2019, nearly a quarter million Americans learned they had lung cancer, and 143,000 died from the disease. Tobacco use was responsible for most of those deaths, but rocks—particularly those containing naturally occurring uranium, which decays over time to produce radon gas—were also partly to blame.
Radon is the second-leading cause of lung cancer in the United States and afflicts people primarily through in-home exposure. The geogenic carcinogen forms as uranium in bedrock, then breaks down into radioactive decay products, and enters homes through cracks and holes in foundations. The Environmental Protection Agency estimates that 1 in 15 homes in the United States has elevated radon levels.
The combination of tobacco smoke and radon is hazardous and poses a significant public health concern, particularly in states like Kentucky, where smoking rates are among the highest in the country and many homes are underlain by bedrock with high radon potential.
To better communicate the risk of radon exposure, Haneberg et al. made a statewide geologically based map of indoor radon potential for Kentucky. The Kentucky Geological Survey, a research center within the University of Kentucky, maintains an interactive Web map service that includes the radon map.
The authors, comprising geologists and public health experts from the university, combined results from nearly 72,000 home radon test kits in Kentucky with the state’s geologic map to develop the new map. The results showed that, on average, homes on limestone, dolostone, and some shales have higher indoor radon concentrations than homes on siltstones, sandstones, and surficial deposits. The authors note that karst features such as caves and sinkholes may facilitate the concentration and rapid migration of radon and thus may be partly responsible for high radon values in limestones.
The authors distilled results for 106 different geologic map categories into five risk classes to communicate indoor radon potential throughout Kentucky. An earlier study estimated that disseminating such information could save lives and an estimated $3.4–$8.5 million per year in health care costs. The researchers say they anticipate that the information will encourage Kentuckians to test for and mitigate radon in their homes. (GeoHealth, https://doi.org/10.1029/2020GH000263, 2020)
—Aaron Sidder, Science Writer