A COMPARISON OF GEOLOGY TO LONG TERM AND SHORT TERM RADON TESTS IN THE METRO AREA OF PORTLAND, OREGON

In recent research, radon has been identified as the second leading cause of lung cancer. Radon gas exists naturally at low levels; it is when the gas becomes concentrated in living spaces that a health hazard arises. The radon distribution in the Portland area was last performed in 2003 for long-term test data, the intent of this analysis is to provide an update to the 2003 data and for the first time examine short-term testing data. The raw data was limited to tests performed in living areas only, and highest reading for a given location. The radon distribution is examined based on zip code geographical boundaries. This examination adds 65 zip codes to the 2003 dataset. Each zip code was examined for maximum radon reading, average radon reading, and percent greater than 4 pCi/L, which work together to determine the radon potential. Based on the long-term data, nearly 81% of homes are located in areas with moderate to high radon potential, while the short-term data indicates that nearly 98% of homes in these ranges. There is some variation in the distribution of radon levels within the Portland metro area and one of the reasons for this is that zip codes cut across geologic boundaries. The geology shows that for most of the high and moderate radon potential areas, porous Missoula Flood deposits or landslide deposits dominate. The underlying geology of a location influences the emission of radon greatly, and is important in the understanding of radon potential.