Based on air pollutant observations in the period from October to November (related with APEC summit), 2014 from meteorological stations of major cities in Beijing-Tianjin-Hebei (BTH) and the surrounding region, the maps of mean air pollutant concentrations every seven (or five) days are obtained with selected spatial interpolation methods. Global autocorrelation and local autocorrelation analysis methods are used to study the spatial heterogeneities of pollutant concentrations, and the spatio-temporal distribution characteristics of pollutants are explored by using kernel density (KD). The followings are revealed:there were significant positive spatial autocorrelations and spatial aggregating features on the mean concentrations of all pollutants; the hot spots of mean PM2.5 concentrations distributed in Tianjin, Shijiazhuang, Baoding, and south Beijing; the hot spots of mean SO2 concentration concentrated mostly in Baoding, Tianjin, Tangshan and Shijiazhuang, while the hot spots of mean NO2 concentrations distributed mainly along BeijingTianjin-Tangshan and Baoding-Shijiazhuang-Xingtai; variations of air quality were notable at different times. Before and during the APEC summit, the regional control/limiting measures and the cold air activity effectively improved the air quality of Beijing and its surrounds, and the KD high value zones transformed gradually into middle or low KD-value zones. With the help of cold air currents and high wind speeds, nice air quality maintained within the first 5 days after the APEC summit. However, air pollutions rebounded sharply and high KDvalue zones gradually extended to most parts of the BTH region six days after the APEC summit. It is clear that spatial structure adjustment of industry and elimination of high air-pollution enterprises in BTH are imperative, and the regional synergic emission control in condition of poor meteorological period should be normalized.

air pollution  /  spatial analysis  /  spatio-temporal features  /  APEC summit  /  BTH region