Mitigating traffic-related particulate matter with evergreen shrubs: A real-world field study in bergamo, Italy

Urban bus stops are critical air pollution hotspots often overlooked in mitigation strategies. While large green spaces are studied, the impact of small-scale vegetation remains less clear. This research evaluated the role of common evergreen shrubs (Prunus laurocerasus and Pyracantha x 'Navaho') in reducing PM₁₀ mass concentration. The study was conducted at a high-traffic bus stop in Bergamo, Northern Italy, during winter (January-February) and autumn (October) 2024, focusing on their potential to improve air quality in dense urban microenvironments. Results showed that the shrubs reduced PM₁₀ mass concentrations by 21% in winter and 16% in autumn compared to adjacent areas without vegetation. Additionally, chemical analysis via ICP-OES and XRF showed that PM_10,-associated metals decreased by an average of 5%, with Cu showing the highest removal rate at 64% followed by Sr (61%). SEM/EDX analysis of plant leaves revealed a chemical profile (Mg, Al, Si, S, Cl, K, Ca, Fe, and Ti) consistent with the atmospheric samples. These findings demonstrate the potential of small-scale, evergreen vegetation to reduce air pollution in traffic-heavy areas. Integrating such green elements into urban planning offers a sustainable, low-cost strategy to improve air quality and public health in densely populated cities.