Atmospheric particles deposited onto leaf surfaces were analyzed using scanning electron microscopy, and the particle types were correlated with the land-use categories of the sampling sites. Mesquite leaves were collected from twenty-five sites throughout the Phoenix metropolitan area during the summer of 2001. The sites were chosen to represent each of five land-use categories: undisturbed (natural desert), soil (prior agriculture, gravel), vegetation (agriculture, grass), residential, and commercial. Individual particles on the mesquite leaflets were analyzed for their sizes, shapes, and chemical compositions using an electron microprobe. Preliminary results show that aluminosilicates and calcium silicates are the most abundant particle types. Two other significant particle types are those rich in sulfur and potassium. The aluminosilicates are abundant at all sampling sites. The calcium silicate and potassium-rich particle types are more abundant at the soil and vegetation sites than at the other sites. Conversely, higher numbers of the sulfur-rich particles are observed at the residential and commercial sites than at the other sites. The results show that individual particles deposited onto leaf surfaces can be analyzed with scanning electron microscopy and that particles deposited onto leaf surfaces are representative of the land-use category from which they were sampled. These results suggest that particle deposition on leaves can be used to measure the spatial resolution at which particle types change along a gradient from the urban core to the natural desert.