Urban street canyons, characterized by their narrow roadways flanked by tall buildings, create complex airflow patterns that significantly influence turbulence and vehicular pollution dispersion. This chapter explores the interplay between urban morphology, atmospheric boundary layer dynamics, and emission sources in street canyons. Computational fluid dynamics (CFD) models and field experiments illustrate how turbulence, eddies, and thermal effects impact pollutant concentration levels. Additionally, the role of meteorological factors, street geometry, and vehicular-induced turbulence is examined to understand dispersion mechanisms. Effective mitigation strategies, including green infrastructure and urban design modifications, are discussed to enhance air quality and reduce human exposure to pollutants. This study provides insights into improving urban air quality through engineering and planning interventions.