This GIS land usage map shows an agricultural area with two residences whose locations are indicated by concentric circles representing buffer zones of increasing size: 250 m, 500 m, 750 m, and 1000 m. Colors indicate what each section of land is used for. In this area, the dominant land usages are row crops and pasture/hay. Scientists estimate exposures—such as pesticide exposure—for each residence by calculating how much area each relevant land usage type covers within the different buffer zones.