USING GIS TO UNCOVER THE LINK BETWEEN RADON POTENTIAL AND GEOLOGY IN WISCONSIN

Radon, the only radioactive gas, is constantly being exhaled from the Earth. Geology plays the primary role in radon potential. For radon to be emitted, the underlying geology must contain uranium for radon production, and be permeable enough for transportation to occur. In 2014, the Wisconsin Department of Health Services published an updated map of radon potential by zip code. Radon potential has some spatial structure across Wisconsin, and there appears to be some correlation between radon hotspots and geology (e.g. the Wolf River Batholith), but in general the correlation is vague. Bedrock geology, soil composition, and soil thickness all influence radon potential, and so to uncover the link between radon potential and geology, all of these geological factors must be considered in unison. Using GIS, zip codes in Wisconsin have been analyzed for their composition in terms of shallow bedrock and thick sediments, utilizing published GIS maps of Wisconsin bedrock, soils, and depth to bedrock. Using a principal component analysis, the units most responsible for low radon potentials and high radon potentials have been assessed. Because the DHS radon potential map has been constructed using a random sampling from each zip code, it is expected that some preferential weighting will be given to different geological units based on the spatial distribution of population density. We are currently in the process of assessing this affect. As the second leading cause of lung cancer in America, it is of critical importance for public health to better understand the connection between geology and radon potential.