| The air quality in Beijing was concerned by people all over the world during 2008 Summer Olympic Games. In order to to present the "Green Olympics" spirit, guarantee a cleaner atmospheric environment for athletes and audience, the abatement of pollutant was developed on a large-scale by Beijing Municipal Government and other Surrounding provinces or cities. In order to monitor the real-time air pollutants (NOX, O3, SO2, PM10 and PM2.5, etc.) continuously during the Beijing Olympics, providing a support to the relevant departments'policy in time, reflecting the security situation to the air objectively, evaluating the effect of regional collaborative pollutant emission abatement, a monitoring network on observation of atmospheric pollutants was established in Beijing, Tianjin and Hebei by Institute of Atmospheric Physics, Chinese Academy of Sciences. We selected several stations of the monitoring network in Beijing and other surrounding cities and analysed the data which were obtained in 2008 and 2009. The results were showed as follows:(1) The primary pollutants in Beijing and nearly surrounding areas are particulates in summer and autumn in 2008. The average mass concentrations of PM10 were (108±66)μg·m-3 and (120±59)μg·m-3 in Beijing and nearby cities, respectively, while the average mass concentrations of PM2.5 were (72±46)μg·m-3 and (77±51)μg·m-3, respectively. The average maximum hourly mass concentrations of O3 were (81±32)×10-9 v/v and (80±29)×10-9v/v, as well as the average mass concentrations of NOx were (31±11)×10-9 v/v and (14±8)×10-9 v/v in Beijing and nearby cities, respectively. Compared with June, concentrations of PM10, PM2.5, NOx decreased by 61%,51% and 40% during the Olympic period (from August 8 to 24) and 62%,54% and 30% during the Paralympic Games period (from September 6 to 17) in Beijing. The mass concentration of PM2.5 was affected by the surrounding areas of Beijing seriously. The relative high concentrations of NOx in Beijing imply NOx had the potential tendency to be transported to the surrounding areas. Ozone showed regional pollution characteristics in summer.(2) In summer and autumn in 2008, a bimodal diurnal variation of NOx was presented in Yanjiao, a small city where situated in east of Beijing. The peaks appeared at around 9:00 am and 20:00 pm. The diurnal variation of O3 presents one peak, which appeared at around 15:00 pm. The diurnal variation of PM10 was completely different before and after regional collaborative pollutant emission abatement. It was dual peaks which peaks appeared at around 9:00 am and 19:00 pm before the vehicle-limited, but no significant diurnal variation of the peak during the pride of vehicle-limited.(3) Correlation analysis showed that the concentrations of NOx in air in Yanjiao and Zhuozhou were significantly influenced by which in Beijing. The concentrations of PM2.5 in air in Beijing were significantly influenced by which in Yanjiao and Zhuozhou, which showed that the key measure of control the particulate in air in Beijing was to control the pollution sources from arounding areas of Beijing. Typical pollution in summer 2008 showed that the concentration peaks of pollutant in Beijing were postponed for 2 to 6 hours in comparison with what in Zhuozhou, Langfang and Xianghe. This showed that the high concentrations of pollutants in Beijing were leaded by the accumulation of pollutants transported from the southwest, south and southeast of Beijing. The analysis combined of meteorological factors showed the lag time of concentration peak's emergence was relevant to wind speed and direction.(4) The concentration of NOx in air is rising gradually from summer to autumn season in 2008 and 2009. The concentration of NOx in period from July 15 to October 31 in 2008 decreased by 21% in comparison with that in 2009, but 46% in period from August 8 to September 17. The concentration of O3 had a decline trend from summer to autumn slightly. The implementation of emission reduction measures played only a small part to SO2 with the fact that SO2 concentration had already be low and not be the major pollutants in this region in the summer and autumn. The concentration of SO2 in air from August 8 to September 17 in 2008 decreased less than 7% in comparison with that in 2009. The concentration of particle showed an increasing trend during these periods. The concentration of particle overtop the standard limit once in a way, though it decreased by 20%.
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