Size segregated atmospheric aerosol samples collected from the summer 2000 Montana forest fires, from Hawaiian sea salt, and from an Asian Dust event reaching Salt Lake City, Utah, in April 2001 have been studied. Multivariate statistical analysis has been used to extract information from the SIMS images. Images of the particles have been separated from the image background, which significantly improved our ability to acquire the composition of individual aerosol particles. Montana forest fire aerosol was predominantly submicrometer, well within the respirable range (PM2.5), and had a characteristic surface composition identified as the amides of stearic acid and palmitic acid. Sea salt showed a layered structure of organic compounds on the surface of aqueous NaCl. The Asian Dust event could be clearly distinguished from normal Salt Lake City particulate pollution. (C) 2002 Elsevier Science B.V. All rights reserved.