Abstract:Using the PM2.5 mass concentration and surface wind data from February 2013 to January 2016 at Chaoyang Environmental Meteorological Station in Beijing, the characteristics of PM2.5 and its influence by surface wind are analyzed. The results show that the annual concentration of PM2.5 is 80.6±4.0 μg·m-3, 2.3 times the annual concentration limits (35 μg·m-3) regulated in the ambient air quality standard (GB3095-2012) of China. Its seasonal variation is obvious with the highest concentration in winter (115.1 μg·m-3) and the lowest in summer (58.5 μg·m-3). The dominant wind direction at Chaoyang Site in Beijing is ENE-E-ESE, and the wind speed ranges between 0.2-2.0 m·s-1. The concentration is the highest (109.1 μg·m-3) in the dominant ENE-E-ESE wind direction and the lowest (39.5 μg·m-3) in WNW-NW-NNW. With the increase of wind speed, PM2.5 concentration increases first and then decreases. The highest concentration (139.2 μg·m-3) appears at the wind speed of 0.4 m·s-1. When the wind speed is in 0.2-2.0 m·s-1, the concentration is mainly affected by ENE-E-ESE, and when the wind speed is 2-6 m·s-1, the value is influenced by ESE more. By comparing with the PM2.5 data from other sites, we found that the different characteristics of pollution sources and ground winds result in the difference of PM2.5 mass concentration in different wind directions.