Abstract. During the 2014 Asia-Pacific Economic Cooperation (APEC) summit, a reduction of air pollution sources was coordinated to ensure good air quality in Beijing and the surrounding provinces and cities. By investigating variations in air pollution during this period, the effects of local emissions and regional transport can be better understood and the information can be used to evaluate the effectiveness of emission reduction strategies and provide a theoretical basis to guide future emission reduction strategies. From 15 October to 30 November 2014, the height of the atmospheric mixing layer and the aerosol attenuated backscattering coefficient profile were observed online using a lidar ceilometer. By investigating the correlation between fine particulate matter (PM2.5) data near the surface and attenuated backscattering coefficients measured by the lidar ceilometer as well as the correlation between aerosol optical depth (AOD) and attenuated backscattering coefficients of the 0 to 4500 m column, we found that the attenuated backscattering coefficient measured by the lidar ceilometer is highly correlated with the PM2.5 concentration and AOD (correlation coefficients of 0.89 and 0.86, respectively). This result demonstrates the reliability of the vertical profile of aerosols measured by the lidar ceilometer. By analyzing the atmospheric backscattering profile, we found that during the initial stage of pollution accumulation, which is affected by transport of southerly jet flows at low altitude, the attenuated backscattering coefficient of atmospheric aerosols from 0 to 1500 m was greatly enhanced by approximately 1.4 Mm-1 sr-1 (140%). At the peak pollution stage, the height of the mixing layer gradually decreased, the ratio of CO/SO2 gradually increased and emissions were dominated by local emissions. The attenuated backscattering coefficient of aerosols from 0 to 300 m suddenly increased, and the aerosols near surface had the highest value (approximately 14 Mm-1 sr-1); however, the attenuated backscattering coefficient of aerosols from 300 to 900 m gradually decreased, and the average value from 0 to 1500 m decreased by 0.5 Mm-1 sr-1 (20%). By comparing the PM2.5 concentrations before, during and after APEC (BAPEC, DAPEC and AAPEC, respectively), we found that the concentration of fine particles decreased by 60% and visibility improved by 60% during APEC. In addition, compared with the BAPEC and AAPEC periods, the contribution of regional transport in the DAPEC period decreased by approximately 36 and 25%, respectively, and the local contribution decreased by approximately 48 and 54%, respectively. Thus, the most effective method of controlling air pollution in the Beijing area is to reduce regional emissions during the initial stage of air pollution and reduce local emissions during the peak pollution stage.