Spatial Gradients - Key Observations -
Chapter 3 concludes that fine particle concentrations are less spatially homogenous in many areas than had previously been assumed.
Chapter 3 states that although PM2.5 concentrations may be highly correlated between sites, the concentrations themselves may not be spatially uniform (i.e., correlation is not a measurement of spatial variability).
Work by Ito et al. (1995) and current work in Dr. Paul Switzer’s research group show that the presence of spatial variability within a study area results in varying mortality estimates.