The report presents the analyses of the particulate situation in the City of Philadelphia conducted as part of the study for the national assessment of the problem of attainment or nonattainment of the National Ambient Air Quality Standards for particulates. The City of Philadelphia represents a highly industrialized area, with above average heating requirements and an average amount of rain, that has had some success in reducing emissions and particulate concentrations though the standards have not been attained. Auto-related factors have been implicated as a major contributing source to the ambient levels of particulates in Philadelphia, so this report provides special emphasis in that area. In addition to the analyses of traffic-related emissions, analyses of the air quality levels, emissions, regulations, monitoring network, meteorology, and construction are included in this report.