Investigating the Impact of Emission Reductions on Ambient PAH and Nitrated PAH Concentrations

JUN MENG, Elisabeth Galarneau, Deyong Wen, Junhua Zhang, Kenjiro Toyota, Verica Savic-Jovcic, Environment and Climate Change Canada

     Abstract Number: 700
     Working Group: Aerosols Spanning Spatial Scales: Measurement Networks to Models and Satellites

Abstract
Polycyclic aromatic hydrocarbons (PAHs) are hazardous air pollutants with potential health impacts, and nitrated PAHs (nitro-PAHs) are known to exhibit even higher toxicity. However, there has been limited research on how the spatial concentrations of PAHs have changed over time. In this study, we investigate the impact of decreasing emissions on ambient PAH and nitro-PAHs concentrations over the past two decades using a regional chemical transport model with high horizontal resolution.

We implement a new nitro-PAH species, 2-Nitrofluoranthene (2-NFLT), into the widely used Global Environmental Multiscale model – Modelling Air quality and CHemistry (GEM-MACH). We evaluate the performance of the model by comparing model predictions with available measurements of 2-NFLT concentrations in ambient air collected within the model domain. By simulating 2-NFLT concentrations for different emission levels over a span of three decades, we aim to identify the changes in 2-NFLT concentrations compared to primary PAH concentrations and quantify how emissions from traffic sector contribute to 2-NFLT concentrations.

Overall, our study emphasizes the importance of fine spatial resolution in nitro-PAH modeling and provides valuable insights into the co-benefits of reducing primary PAH emissions and NOX emission through emission reductions over the past two decades. The findings from this work can inform policy decisions regarding air quality improvement and public health protection.