Quantification of the Spatial Variation and Source Contributions to Ambient Particle-Bound PAHs Using Aerosol Mass Spectrometry

indicating a 2.1-fold difference, with the downtown neighborhood exhibiting the highest intra-neighborhood variability (Q3/Q1 = 3.4). Compared to Black Carbon (BC), particle-phase PAHs showed greater spatial variability. Most of the detected particle-phase PAHs had low background concentrations and the time series of concentration was punctuated by high concentration spikes. These spikes occurred most frequently in high-traffic zones such as Downtown and on major highways, suggesting contributions from vehicle traffic. Additional spikes in industrial areas suggest contributions from industrial sources. Ratio-ratio plots (e.g., PAH/BC) and comparison of particle-phase PAH concentrations with the concentrations of hydrocarbon-like organic aerosol (HOA), an indicator of vehicle emissions, further indicate the importance of vehicle emissions on ambient particle-phase PAH concentrations. However, vehicle emissions cannot fully explain particle-phase PAH concentrations in the mobile sampling data. Other sources including metallurgical coke emissions and asphalt paving emissions may also be important. Supplementary Information: The online version contains supplementary material available at 10.1007/s44408-026-00109-2.