Date of Award


Document Type


Degree Name

Master of Science (MS)


Geography & Geographic Information Science


Indoor radon may be a potential health threat in a significant number of homes in Grand Forks, North Dakota. Ninety-three percent of the homes tested in 1988 to 1993 contained indoor radon levels greater than the Environmental Protection Agency’s recommended action level of 4 picoCuries per liter. In addition, the average reading of indoor radon concentrations was 18.9 picoCuries per liter, well above the action level guidelines.

Several variables were examined through the use of regression analysis and a Geographic Information System in an attempt to characterize the controls on indoor radon levels in Grand Forks. The results of the analysis indicated no significant relationship with any of the variables tested: soil permeability, distance to surface water bodies, and house age. Bedrock and surficial geology are mainly homogeneous in nature and contain primarily shale, limestone, and sandstone which have been found to have high uranium concentrations. Therefore the bedrock and surficial geology play an important role in influencing high indoor radon levels. The outcome of the study led to the formulation of several alternative hypotheses for future studies. Studies investigating meteorological factors as well as building materials may prove to have a positive relationship with indoor radon levels in viii Grand Forks.