Quantifying Urban Air Quality Across Global Megacities

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 PM_2.5, 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 PM_2.5, PM₁₀, Ozone (O₃), Nitrogen Dioxide (NO₂), and Sulfur Dioxide (SO2). According to our findings, Shanghai exhibited an overall decrease in PM_2.5 and SO₂ levels over the period, while concentrations for O₃ and PM₁₀ remained stable. Delhi showed significant seasonal fluctuations in PM_2.5 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 PM_2.5, PM₁₀, and NO₂ levels, exhibiting the effectiveness of their measures in reducing emissions from vehicle and industrial sources.

PM_2.5 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 PM_2.5 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.