SPECIFIC SURFACE-AREA OF URBAN ATMOSPHERIC PARTICULATE MATTER IN PORTLAND, OREGON

Urban particulate matter was collected in Portland, OR, during the summer of 1992. Various filter types were used as collection media. Surface areas measured for blank filters were subtracted from the total surface area of loaded filters to determine the specific surface area of atmospheric particles. Observed specific surface areas were 0.82 +/- 0.27, 1.7 +/- 0.4, and 2.4 +/- 0.7 m(2)/g for particles collected on polytetrafluoroethylene (PTFE) membrane, PTFE-coated glass-fiber, and glass-fiber filters, respectively. Although PTFE membrane filters had the lowest blank values for surface area, possible particle aggregation on such filters during sampling may make their use for surface area determinations problematic.