Abstract:
Based on the hourly PM2.5 concentration data from the Ministry of Ecology and Environment of China and the NCEP FNL meteorological reanalysis data, this study constructed a PM2.5 Pollution Meteorological Index (PMI) through correlation analysis and examined the changes in PM2.5 pollution meteorological conditions and their impacts on PM2.5 concentration in four typical regions in Central-East China (Beijing–Tianjin–Hebei, Fenwei Plain, Yangtze River Delta, and Pearl River Delta) during winter from 2014 to 2020. The analysis of PM
2.5 concentration changes showed that during the winters of 2014–2020, the near-surface PM
2.5 concentration decreased at 96.5% (305/315) of the sites in Central-East China, and the number of heavily polluted days with PM2.5 reduced at 89% (251/282) of the sites. The decline rates of PM2.5 concentration in the Beijing–Tianjin–Hebei, Yangtze River Delta, and Pearl River Delta regions were 9.3, 6.3, and 2.9 µg m
−3 a
−1, respectively. In the Fenwei Plain, the PM2.5 concentration increased during the winters of 2014–2016 and then decreased during the winters of 2017–2020. The constructed PMI showed a strong positive correlation with the regional average PM2.5 concentration during the winters of 2014–2020, with correlation coefficients of 0.71, 0.71, 0.71, and 0.61 for the Beijing–Tianjin–Hebei, Fenwei Plain, Yangtze River Delta, and Pearl River Delta regions, respectively, indicating the reliability of the PMI. The analysis of PMI changes indicated that during the winters of 2014–2020, no significant trend in the meteorological conditions affecting PM2.5 occurred in the Beijing–Tianjin–Hebei, Fenwei Plain, and Pearl River Delta regions, while the meteorological conditions in the Yangtze River Delta region improved significantly (with a PMI decrease of 0.33/a). Comparative analysis of the PM2.5 concentration, PMI, and changes in anthropogenic emissions showed that the decline in near-surface PM2.5 concentration in the Beijing–Tianjin–Hebei and Pearl River Delta regions during the winters of 2014–2020 was mainly due to the reduction of anthropogenic emissions and that the Yangtze River Delta region was affected by the improved meteorological conditions. The increase in near-surface PM2.5 concentration in the Fenwei Plain during the winters of 2014–2016 was a result of deteriorating meteorological conditions.