Coupling coordination relationships between air pollutant concentrations and emissions in China

Abstract

Clarifying the correlations between air pollutant concentrations and emissions is vital for effective air pollution prevention and control. In this study, we established a coupling coordination degree model to explore the coupling coordination relationships between concentrations and emissions of PM2.5, SO2, and CO from 2013 to 2017. Moran's I value was used to analyze the spatial distributions of coupling and coordination degrees, and seven socioeconomic, meteorological, and ecological indicators were selected to identify the potential influencing factors. The results indicate that the PM2.5 coupling degree decreased from 2013 to 2017, whereas those of SO2 and CO increased. The five-year average coupling degrees were 0.73, 0.71, and 0.63, respectively. The coordination degrees of PM2.5, SO2, and CO all increased during the study period, with five-year averages of 0.43, 0.32, and 0.45, respectively. Both the coupling and coordination degree distributions of all three air pollutants exhibited significant spatial agglomeration characteristics. Generally, the coupling coordination levels of air pollutants in China were high in the east and low in the west. In addition, the levels in the northwest were higher than those in the southwest. Of the influencing factors, nighttime light, road-person ratio, and wind speed were positively correlated with the coupling coordination levels. The normalized difference vegetation index and precipitation was negatively correlated with the coupling coordination levels. These findings can be used to improve the current understanding of correlations between air pollutant concentrations and emissions and provide a reference for decision-makers to formulate more effective air pollution prevention and control strategies.