Spatiotemporal Dynamics of Urban Air Pollution in Dhaka City (2020–2024) Using Time-Series Sentinel-5P Satellite Images and Google Earth Engine (GEE)

This study investigated the spatiotemporal dynamics of four major air pollutants—carbon monoxide (CO), nitrogen dioxide (NO2), sulphur dioxide (SO2), and ozone (O3)—across Dhaka from 2020 to 2024 using Sentinel-5P TROPOMI satellite data. A 60-month time-series analysis was conducted, integrating spatial mapping, seasonal composites, and Mann–Kendall trend testing. Results indicated clear seasonal variations: CO and NO2 concentrations peaked during winter, with maximum monthly averages of 0.05287 mol/m2 and 0.00035 mol/m2, respectively, while SO2 reached a high of 0.00043 mol/m2 in pre-monsoon months. In contrast, O3 peaked in May (0.13023 mol/m2), following an inverse seasonal trend driven by photochemical activity. Spatial analysis revealed persistent pollution hotspots in central-western zones like Tejgaon and Mirpur for CO and NO2, while SO2 was concentrated in southern industrial zones such as Keraniganj and Jatrabari. The Mann–Kendall test identified moderate to strong increasing trends for CO (τ = 0.8, p = 0.086 in June and September) and SO2 (τ = 0.8, p = 0.086 in April and May), although most trends lacked statistical significance due to the limited temporal window. This study demonstrates the viability of combining satellite remote sensing and cloud-based processing for urban air quality monitoring and provides actionable insights for targeted seasonal interventions and evidence-based policymaking in Dhaka’s evolving urban context.