Spatiotemporal pattern of air quality index and its associated factors in 31 Chinese provincial capital cities

Abstract

Understanding the spatiotemporal characteristics of ambient air quality and identifying the associated factors are helpful to develop integrated interventions to prevent and control air pollution. Based on daily data of air quality index (AQI) in 31 Chinese provincial capital cities in 2014, this study aimed to investigate the spatiotemporal variations of ambient air pollution and the influencing factors. The spatial and temporal patterns of AQI were presented using GIS map and heat map, respectively. We constructed a hierarchical linear model to quantify the effects of meteorological and socioeconomic factors on AQI. In 2014, the air quality nonattainment (AQI >100) rate was 34.6% on average (1.9 to 74.4%). Air pollution levels were highest in winters and lowest in summers. We found substantial spatial variations of AQI, with the highest values in the middle-east area of the North China Plain. The city-level AQI was positively associated with vehicle population, industrial dust emission, and GDP per capital, which cumulatively explained 67.5% of spatial variations of AQI. The city-level AQI also increased with city’s annual atmospheric pressure but decreased with annual mean temperature. Daily AQI within a city decreased with daily temperature, sunshine duration, wind speed, precipitation, and relative humidity. The national analyses indicate that the ambient air quality in China exhibits significant geographical and seasonal variations which were mainly driven by socioeconomic and meteorological factors. The findings would help to understand the underlying reasons for spatial health disparities and would provide important information to guide targeted policy response to ambient air pollution.