A soiling study was performed at an air monitoring site operated by the Research Triangle Institute in the relatively rural environmental conditions within Research Triangle Park, N.C. The study was designed to determine how various environmental factors contribute to the rate of soiling of white painted surfaces. Significant factors that were monitored were hourly rainfall and wind speed, and weekly data for dichotomous sampler measurements and total suspended matter concentrations. Gloss and flat white paints on hardboard were exposed vertically and horizontally, both protected and unprotected from rain for 16 weeks. Measurements of exposed samples were taken at two, four, eight, and 16 weeks. Reflectance was measured and scanning electron microscopy (SEM) stubs, which had been flush-mounted into the hardboard prior to painting, were removed at these times. Particle size distributions were determined by scanning electron microscopy. (Copyright (c) 1990 Elsevier Science Publishing Co., Inc.)