Traffic congestionTraffic congestion isHeterogeneous traffic-induced air pollution a condition in transit that may exponentially slow down vehicular flow and increment vehicular queue. Heterogeneous traffic refers to varied average speeds of multiple vehicles that increase traffic congestionTraffic congestion. Literature reveals that traffic congestion is one of the main reasons for air pollutionAir pollution due to vehicular emissions. Traffic congestion increases vehicular emissions and degrades the ambient air quality. It was also observed after literature review that there is limited research published on the impact air pollution due to the vehicular congestion. The study uses both secondary data to identify the vehicular emitted pollutants and primary data at major traffic intersection points, to understand the nature of traffic congestionTraffic congestion and the vehicular flow nature in the Kolkata Municipal Corporation. A total of 31 key locations were chosen based on observed patterns of traffic congestion. The fleet of vehicles chosen were two-wheelers, four-wheelers and heavy vehicles. Data was collected at different times of the day to capture peak and the lag traffic hours. The results revealed a negative correlation between vehicle speed and emission levels, with greater emissions occurring at reduced traffic velocities. Locations such as Sinthi More, Chira More, Sealdah, Shyam Bazar, P.G. Hospital, and Garia Sitala Mandir exhibit high concentrations of vehicular pollutants. The nature of pollutants revealed were Suspended Particulate Matter (SPM), Respirable Particulate Matter (RPM), and Carbon MonoxideCarbon monoxide (CO), particularly during daytime. The study concludes that a heterogeneous vehicular fleet has exposed the city to a variety of harmful pollutants with more variations, spatially across the city.