University Of Tehran Press Pollution 2383-451X 12 1 2026 01 01 Dynamic Modeling of Urban Passenger Car Emissions in Metropolitan Tehran Based on VSP and the IVE Model 140 152 105143 10.22059/poll.2025.395271.2934 EN Maryam Saberiyansani Environmental Engineering Department, Shahid Beheshti University, Tehran, Iran Yousef Rashidi Environmental Engineering Department, Shahid Beheshti University, Tehran, Iran Seyed Hossein Hashemi Environmental Engineering Department, Shahid Beheshti University, Tehran, Iran Journal Article 2025 05 13 Urban air pollution caused by light-duty passenger vehicles poses critical environmental and public health challenges in megacities like Tehran. In this study, we dynamically estimated vehicular emissions by collecting second-by-second speed and acceleration data from 16 representative routes, including 2 residential, 8 urban, and 6 highway segments, across metropolitan Tehran. We integrated the Vehicle Specific Power (VSP) method with the International Vehicle Emissions (IVE) model to assess real-time emission patterns across four time intervals (08:00, 12:00, 16:00, and 23:00). Our measurements showed that average speeds ranged from 14.0 to 25.97 km/h in residential areas, 10.62 to 42.13 km/h in urban corridors, and 16.43 to 67.15 km/h on highways. We found that VSP values predominantly fell within bins 8–14, reflecting acceleration-intensive and stop-and-go traffic during peak hours. We estimated emissions per kilometer as follows: CO (0.47–0.57 g), NOₓ (0.11–0.23 g), CO₂ (240.7–411.5 g), VOC (0.13–0.19 g), and NMVOC (0.12–0.18 g). During peak hours, emissions increased by 40–50% compared to off-peak periods, correlating with VSP clustering around bins 8–10, while smoother traffic conditions (VSP ≥12) during off-peak hours reduced emissions. This study is among the first in the region to combine second-by-second VSP profiles with the IVE model to produce high-resolution, time-resolved urban emission estimates. Our findings highlight how dynamic traffic modeling can help policymakers design smart traffic signal systems, manage congestion, and improve air quality policies tailored to real-time conditions in megacities.  https://jpoll.ut.ac.ir/article_105143_31c926ddc28c28a3904e14e170dc8235.pdf