TEMPORAL AND SPATIAL VARIATION CHARACTERISTICS OF PM2.5 CONCENTRATION IN “2+26” CITIES

Abstract. In recent years, air pollution is still a serious problem in China. Therefore, the government has further strengthened the pollution control measures for the Beijing-Tianjin-Hebei (BTH) air pollution transmission channel cities (“2+26” cities). This study used real-time PM2.5 monitoring data from 176 air quality monitoring sites in “2+26” cities from 2015 to 2018. The temporal and spatial evolution characteristics of PM2.5 concentration in “2+26” cities were analysis by statistical analysis and Kriging interpolation method. The research results showed that: (1) From the analysed of time variation, the hourly variation presents a bimodal distribution, with the PM2.5 concentration reaching the peak at 9:00–10:00 O’clock and 22:00–00:00, and finally dropping to the lowest value at 16:00–17:00. The monthly change of PM2.5 concentration was almost the same, reaching the peak pollution concentration in December. The seasonal variation trend of the study area was almost the same, and the PM2.5 concentration had a small decline, except for the special changed in winter. However, autumn and winter were still the most polluted seasons, while the spring and summer were less polluted. (2) From the analysed of spatial variation, the pollution process started in November and ended slowly in March of the following year, with the worst and most extensive pollution in December. It was spread to surrounding cities by Baoding, Shijiazhuang, Xingtai and Handan in the central region, and the central area was the most polluted. In August, PM2.5 concentration was the lightest, with an average concentration of 42.4 μg/m³.