Controlling air pollution in the Jing-jin-ji urban agglomeration (JJJUA), the most seriously polluted area in China, is related to the integrated development strategy for the region. Based on the national and regional implementation of air pollution control measures in recent years, the hierarchical cross-regional multi-directional linkage (HCML) air pollution prevention and control model was applied in this study. The effect of air pollution control was evaluated by monitoring the pollutants, SO2, NO2, PM10, PM2.5, O3, and CO, at 112 monitoring sites in 13 cities in 2014-2015. The results can be summarized as follows:① The HCML model is an interrelated framework at the horizontal and vertical level. Under the efforts provided by the central, urban agglomeration, and city governments, this multi-level governance model serves as an effective tool to resolve the issues related to air pollution beyond the borders of municipalities. Environmental regulations on certain industries, energy consumption structure, car ownership and usage, and air quality supervision and warning systems are well established under this governance model. ② The air quality of the JJJUA has improved significantly in the past two years. The concentrations of air pollutants significantly decreased, with the exception of O3, and high pollution ranges significantly reduced from north to south. The annual average concentrations of PM2.5, PM10, SO2, NO2, and CO decreased by 17.84%, 14.61%, 37.55%, 4.82%, and 16.18%, respectively. The number of days meeting the air quality standards increased for all pollutants except NO2. Based on the current situation and unsolved problems of air pollution, the JJJUA area needs certain measures including diversifying the governance subjects, joint legislation (beyond municipalities) on air pollution to regulate pollution discharge, enhancing public awareness on air pollution and its health impacts, carefully examining sources of air pollution in winter to reduce pollution, and to better understand the sources of ozone and adopt effective control measures.
Keywords: Beijing-Tianjin-Hebei region; air pollution; control effect; model summary.