A recent study conducted by professor ZHANG Qinghua’s group showed that the air concentration of dioxins in Beijing have been obviously decreased during 2008 Olympic Games due to the implementation of related measures. Detail study has been published in Environ. Sci. Technol. (ASAP，DOI: 10.1021/es103926s).

In order to improve the air quality and greet the 2008 Olympic Games in Beijing, the government expedited the implementation of comprehensive emission-control measures, including relocating or closing heavily polluting industries, converting coal-burning facilities to natural gas, applying new vehicle emission standards, and implementing temporary restrictions on vehicle use during the Beijing Olympic Games. Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) are persistent and toxic organic pollutants, and might cause cancer even at low concentration. The effect of adopted measures for improving air quality on dioxins reduction is also a public’s concern.

In order to assess the effectiveness of long-term and short-term emission-control measures in reducing dioxins in the atmosphere, 120 air samples were collected at three urban and one rural locations in Beijing, before, during, and after the Beijing 2008 Olympic Games (BOG), in the summers of 2007-2010. During the BOG (August, 2008), the dioxins concentrations fell by approximately 70% from the average in 2007 and by 30% from that in July 2008 before the Olympic event. No significant relationship were found between meteorological parameters (temperature, humidity, and wind speed) and dioxins level, whereas the dioxins concentrations were significantly dependent on the air quality. The half life of dioxins in air was estimated to be from 3.2 to 5.8 years.