The spatial and seasonal complexity of PM2.5 pollution in cities from a social-ecological perspective.

Cities in developing countries worldwide are facing severe fine particulate matter (PM 2.5) pollution. Numerous studies have been conducted to investigate how biophysical and socioeconomic factors affect PM 2.5 concentration. However, most of these studies have typically focused on biophysical and socioeconomic factors separately rather than taking an integrated social-ecological perspective. Cities are widely recognized social-ecological systems, and such an integrative perspective is crucially important for understanding the generation and mitigation of PM 2.5 pollutants. In this study, by considering socioeconomic, biophysical, and meteorological factors simultaneously, we took a comprehensive social-ecological perspective to assess the impacts of these factors on PM 2.5 concentrations. Correlation analysis and variance partitioning were used to quantify the impacts and relative importance of the factors. The analysis was conducted across mainland China focusing on 88 major cities based on socio-economic data, monitoring data of air quality and meteorological conditions, and land cover data. The statistical analysis results revealed that: (1) The biophysical structure and socio-economic factors significantly affect urban PM 2.5 levels year round, but the impacts of meteorological factors are significant only in winter. The biophysical structure factors and the socio-economic ones contribute equally to the variations in PM 2.5 concentration. (2) The effects of the factors vary by region. In northern China, the socio-economic factors together with meteorological factors contribute the most to the variation of PM 2.5 concentration. In southern China, however, the unique effect of meteorological factors is dominant in affecting the level of PM 2.5. (3) Air temperature has a positive relationship with the concentration of PM 2.5 in northern China, but a negative relationship in southern China, which might indicate the varied dominant precursors of PM 2.5 between the two regions. This study extends our understanding of the effects of social-ecological factors on urban PM 2.5 pollution and underscores the importance of differentiated strategies for air pollution mitigation in different regions, and in different seasons, which provides a scientific basis for sustainable development from the perspective of urban air pollution mitigation. [Display omitted] • Biophysical structure, socioeconomic and meteorological factors all affected PM 2.5 • In northern China, Social economy and meteorology together affected PM 2.5 • In southern China, the meteorological factors dominated the variation of PM 2.5 • Temperature had contradictory effects on PM 2.5 between Northern and Southern China. [ABSTRACT FROM AUTHOR]