Does Vehicular Growth Affect Dhaka’s Air Quality? Evidence From Time-Series Analysis

Abstract

Air pollution in Dhaka, one of the most densely populated and traffic-congested cities in the world, has reached alarming levels, with vehicular emissions identified as a major contributor. This study examines the relationship between vehicular growth and air quality using time-series data from 2013 to 2023. Applying Autoregressive Distributed Lag (ARDL), Vector Error Correction Model (VECM), and Seasonal ARIMA with Exogenous Regressors (SARIMAX), it investigates both short-run and long-run effects of vehicle registration trends on Dhaka’s Air Quality Index (AQI). Findings indicate that motor vehicles and cargo transport significantly deteriorate air quality in the long run, while seasonal variations influence pollution fluctuations. Winter months experience the worst air quality due to atmospheric stability and temperature inversions, whereas monsoons aid pollutant dispersion through rainfall. Notably, the rise in private vehicles did not directly correlate with worsening air quality, suggesting improvements in fuel efficiency and emission standards. However, the surge in motorcycles, especially after ridesharing services emerged, contributes heavily to hydrocarbon emissions. The study underscores the need for targeted policies, such as stricter emission norms, congestion pricing, and greater investment in sustainable public transport infrastructure.