Characteristics of Atmospheric Pollution in a Chinese Megacity: Insights from Three Different Functional Areas

Abstract

The most important atmospheric pollutants include PM_2.5, PM₁₀, SO₂, NO₂, CO and O₃. Characteristics of atmospheric pollution were investigated by analyzing daily and hourly concentrations of the six key pollutants in three different functional areas (urban, suburban, and rural) of Shanghai during 2019–2021. Results show that O₃, exceeding PM_2.5, has become the primary pollutant determining air quality in Shanghai. The frequency of O₃ as a primary pollutant ranged from 40% in an urban area to 71% in a rural area, which was much higher than that of PM_2.5 (14–21%). NO₂ and SO₂, precursors of PM_2.5, presented a clear weekend effect, whereas PM_2.5 at weekends seems higher than that on weekdays. In the warm season, O₃ at weekends was higher than that on weekdays in the three different functional areas, whereas no significant difference was observed between O₃ on weekdays and at weekends in the cold season. Potential source contribution function analysis indicated that air pollution in Shanghai was impacted by inter-regional and intra-regional transport. The potential source areas of PM_2.5 and O₃ were different, which brought challenges to the coordinated control of PM_2.5 and O₃ in Shanghai. This study emphasizes the prominent O₃ pollution in Shanghai, and argues that the prevention and control of O₃ pollution requires regional joint prevention and control strategy.