The characteristics of environmental particulate matter in the urban area of Beijing, China, during the 2008 Olympic Games

Atmospheric particulate matter (PM) and street dust samples from the Chaoyang District of eastern Beijing were studied over a period encompassing the 2008 Beijing Olympic Games. PM10 concentration data are combined with trajectory clustering and potential source contribution function (PSCF) methods to identify the principal transport pathways. Sources for high-concentration aerosol events and airflow from the surrounding Hebei Province and Shandong Province to the southeast are found to exert the most significant external influence on Beijing's air quality. China undertook a number of initiatives to improve air quality for the Olympic Games and we show that PM10 concentrations and magnetic susceptibility were significantly lower during the Olympic period compared to the pre-Olympic period confirming that controlling local sources in Beijing and shutting factories in surrounding provinces substantially improved air quality. On short timescales PM10 shows an inverse correlation to relative humidity and hence precipitation which acts to improve air quality. Atmospheric PM and street dust remained high through the Olympic period probably due in part to redistribution of historical sources and implying that the aim of zero pollution is not achievable in the short term. Analysis of the heavy metal content in both PM and street dust identifies consistently high values of Zn, with Pb relatively higher in the PM; a primary source in vehicular emissions therefore seems likely.