A study on the impact of street trees on PM10 dispersion in urban areas using the Graz Lagrangian Model

Abstract Urban air pollution, particularly from PM10, presents significant health risks, especially in rapidly growing cities. This study utilizes the Graz Lagrangian Model to analyze PM10 dispersion along Avenida da Liberdade in Lisbon, an area characterized by high traffic, tall buildings, and a dense canopy of street trees. The study examines how wind patterns, atmospheric stability, urban characteristics, and vegetation influence pollutant distribution. The results show that, in the current scenario with trees, PM10 concentrations were significantly higher at points near the emission source, indicating that, in this specific study of an avenue with extensive tree coverage, trees impede ventilation and hinder PM10 dispersion. In contrast, in a hypothetical scenario without trees, pollutant dispersion was less obstructed, leading to lower concentrations but a broader spatial distribution, particularly at more distant points. The study also found that increased traffic did not significantly elevate PM10 concentrations during periods of atmospheric instability. Limitations of the model, including its inability to accurately represent individual trees background pollutant levels, are acknowledged. These findings contribute to a deeper understanding of urban pollutant dynamics and can inform air quality management strategies, particularly in areas with dense street tree coverage.