EPA is developing an empirical model to relate ambient air quality to particulate emissions and land use in the surrounding area. This receptor-oriented model will be used for evaluating the effect of particulate control measures on concentrations at individual sites in a sampling network or for predicting air quality at a location where there is no sampler. PEDCo Environmental is collecting most of this detailed data base used in the study and providing it to the EPA in the form of a series of reports, one for each of the five cities in which sites are to be surveyed: Kansas City, Portland, St. Louis, Birmingham, Philadelphia. Each of PEDCo's reports follow the same format, and the reports are confined almost entirely to data presentation. The present report summarizes information for sites in the Portland area. The 10 high volume sampling sites inventories in the Portland area have a wide distribution of exposures ranging from industrial to background.