Air Quality Characteristics and Their Natural and Socioeconomic Drivers in Beijing-Tianjin-Hebei Economic Zone, Northern China

Beijing-Tianjin-Hebei Economic Zone is one of the most polluted areas in northern China. In recent years, pollution has become one of the most severe the environmental problems in that region, posing huge impact on the urban traffi c and threatening the public health greatly. Understanding the spatio-temporal variability and their mechanisms is important for the monitoring and control of regional air pollution. This study employed the Mann-Kendall test, statistical methods, geographical spatial analysis, aiming to explore the characteristics of air quality and its main controlling factors in this region. Temporal analysis was conducted in four largest cities to indicate the variation trend of air quality and identify the infl uence of meteorological factors, while spatial analysis was conducted based on all 13 cities of the region to clarify the socioeconomic controls on air quality. The results from trend analysis indicate an improving trend in air quality. Temperature, air pressure and wind speed are the main meteorological factors controlling air quality in the four large cities, which impose important infl uence on the migration, diffusion or settlement of pollutants. Agglomeration degree and distribution characteristics of AQI and six pollutants show great spatial heterogeneity, which is determined by topography, land-sea position, physicochemical properties of pollutants and socioeconomic factors. Principal component analysis (PCA) indicate that economic development benefi ts the improvement of air quality, while industrialization and traffi c construction aggravate air pollution. The air quality is less dependent on the level of urbanization. About 55 % of the spatial AQI changes can be explained by the socioeconomic factors, suggesting the leading contribution of human activities to air quality. This study will help deeply understand the main sources of air pollution in Beijing-Tianjin-Hebei region, and provides insights for urban planning and rational policy formulation that are conducive to air pollution control.