Spatial variation in particulate concentrations within metropolitan Philadelphia

During the summers of 1992 and 1993, particle mass concentrations (PM2.5 and PM10) were measured at eight sites located within metropolitan Philadelphia. Particle sampling was performed simultaneously at these sites on alternate days during the summer of 1992 and every day at seven of these sites during the summer of 1993. Sampling was conducted over 24-h periods beginning at 9 am (EDT) during both summers. All PM2.5 and PM10 samples were collected using 10 L/min inertial impactors with particle cutpoints of 2.5 and 10 μm, respectively. In this paper, we examine the relationship among PM2.5, coarse particulate (2.5 < da < 10 μm), and PM10 concentrations. In addition, we analyze their spatial variation and compare our findings with those made in an earlier study of sulfate (SO42-) concentrations. PM2.5 and PM10 concentrations were found to be relatively uniform across Philadelphia, suggesting that concentrations measured at a single monitoring site are able to characterize particulate concentrations across...