In this study, we implement a mobile monitoring methodology in order to determine the spatiotemporal distribution of particulate matter (PM) and black carbon (BC) in Philadelphia, PA, USA. Over the course of 12 days between June 27, 2019 and July 29, 2019, we measured air pollution concentrations across two replicated 150-mile long routes. Mean concentrations for each pollutant were 11.25 ± 5.43 ug/m3 (PM1), 11.08 ± 6.25 ug/m3 (PM2.5), 15.57 ± 8.51 ug/m3 (PM10), and 1.27 ± 0.80 µg/m3 (BC). We find that finer PM size fractions (PM2.5 and smaller) constitute approximately 71% of PM10. Air pollution hotspots across three size fractions of PM (PM1, PM2.5, and PM10) and BC were present throughout Philadelphia, but were most prevalent in the North Delaware, River Wards, and North planning districts. A plurality of air pollution hotspots found throughout the data collection period (30.19%) occurred between the hours of 8:00 AM – 9:00 AM. Despite significant temporal variation, pollutant concentrations, except for PM10, clustered temporally with a separation before 12 PM. Our approach and findings identify times and places where pollutant concentrations are highest, which is integral to effective air pollution reduction in urban environments.