Urban air pollution poses a significant threat to both human health and the integrity of built environments. Given their substantial potential in mitigating and managing vulnerabilities and risks, architectural engineering and urban planning represent vital disciplines whose scientific research plays a pivotal role in the preservation of the built environment. Given the complex relationship between urban layout, meteorological conditions, greenery parameters, and atmospheric pollutant concentrations, several studies have established frameworks and guidelines around the urban canopy axioms. However, the previous research methodologies revealed certain gaps in our comprehension of this intricate dynamic, hindering the comprehensive assessment of urban air pollution. Specifically, the intricate dynamics of dispersion and deposition of Particulate Matter (PM) with the presence of urban green infrastructure (UGI) constitute significant challenges within the confines of narrow urban spaces. This poses a significant obstacle for policymakers and urban planners, despite the array of available scientific methodologies, as UGI intervention is mostly tailored to specific contexts. This paper synthesizes an analytical methodology for assessing the dispersion and deposition patterns of particulate matter within deep urban canyons. Through an empirical investigation of different vegetation interventions within a prototypical setting in Alexandria, Egypt, the study dissects the intricate interplay of variables influencing dispersion and deposition indicators. The findings reveals that, even within a narrow and low-porosity canyon, dispersion remains a highly influential factor in PM concentration, surpassing the deposition impact, while the latest exhibits minimal impact primarily affecting lower heights. The research underscore the imperative to address these two distinct aerodynamic mechanisms separately, as each holds potential implications for air quality at different heights within the urban canyon environment.