Figure 1From: U.S. census unit population exposures to ambient air pollutantsThe demonstration of spatial relationships between BGs and grids. The four nearest neighboring grids (g) for BGs 1-6: BG1: g5, g6, g9, and g10; BG2: g5, g6, g9, and g10; BG3: g2, g3, g6, and g7; BG4: g3, g6, g7, and g11; BG5: g6, g7, g10, and g11; BG6: g7, g8, g11, and g12.Back to article page