Temporal Variation and Comparison of Particulate Matter Levels Before, During, and After the COVID-19 Pandemic in Dhaka City, Bangladesh: Analysis of Historic Data and Current Trend

This study analyzes the temporal and seasonal variations in particulate matter (PM2.5 and PM10) levels in Dhaka, Bangladesh, with a focus on the periods before, during, and after the COVID-19 pandemic. Secondary data (2017-2023) from two Continuous Air Monitoring Stations (CAMS) located at Farmgate and Darussalam were analyzed alongside recent primary data (November 2024-January 2025) obtained through a portable air quality monitoring device. Findings demonstrated persistently high PM concentrations, especially during winter, regularly exceeding Bangladesh’s National Ambient Air Quality Standards. The initial phase of the COVID-19 lockdown led to a temporary reduction in PM2.5 (by 38.5%) and PM10 (by 21.9%), but levels rebounded post-lockdown, with recent data indicating even higher pollution levels. Seasonal analysis revealed winter peaks and monsoon-related declines. Strong correlations exist between PM2.5 and PM10, and the higher PM2.5/PM10 ratio demonstrated a predominance of pollution from finer particles. Comparative analyses with other global megacities highlighted a similar trend in particulate pollution during the COVID-19 lockdown. The study recommends urgent policy interventions, including emission controls and sustainable urban development, to improve air quality and protect public health in Dhaka, with broader relevance for rapidly urbanizing cities in the Global South.