This study aims to understand the trends in air pollutant concentrations across five megacities, Shanghai, Delhi, Paris, Los Angeles, and São Paulo, from the year 2018-2020. Relevant Air Quality Data for PM2.5, PM10, O3, NO2, and SO2 were obtained from sources such as the World Air Quality Index and the U.S. Embassy and Consulates’ air quality monitors, and compared with various meteorological elements to ascertain the annual and seasonal trends in air quality. The findings revealed significant variations in key pollutants such as PM2.5, PM10, Ozone (O3), Nitrogen Dioxide (NO2), and Sulfur Dioxide (SO2). According to our findings, Shanghai exhibited an overall decrease in PM2.5 and SO2 levels over the period, while concentrations for O3 and PM10 remained stable. Delhi showed significant seasonal fluctuations in PM2.5 and PM10 levels, with the highest pollution levels during the paddy burning season and the lowest during the monsoon season, with a notable reduction in NO2 and SO2 concentrations, reflecting better vehicular and industrial emissions standards. Paris displayed a clear downward trend in PM2.5, PM10, and NO2 levels, exhibiting the effectiveness of their measures in reducing emissions from vehicle and industrial sources.
PM2.5 and PM10 levels in Los Angeles showed slight variations throughout the year with sudden unexpected peaks in air pollution, with a consistent decline in NO2 and SO2 concentrations, indicating improved air quality management. São Paulo showed variability in PM2.5 and NO2 levels, while O3 concentrations fluctuated, reflecting the complexities of urban pollution control. This study highlights the impact of regulatory measures, industrial activities, and meteorological conditions on air quality, and emphasizes the importance of continuous monitoring and effective pollution control strategies.
