Dioxin Levels Dropped 70% During Beijing Olympics

To protect the health of athletes during the Olympic Games in August 2008, Beijing officials took drastic steps to improve the city's air quality. They banned more than half of the city's 4 million cars from the road, shut down polluting industries, and converted coal-burning factories to natural gas. A new study has found that those efforts resulted in a temporary drop in the city's levels of dioxins, which are toxic pollutants linked to reproductive problems and cancer in human beings (Environ. Sci. Technol., DOI: 10.1021/es103926s).

Researchers at the Chinese Academy of Sciences and the University of Illinois, Chicago, analyzed 120 air samples collected in Beijing during the summers of 2007 through 2010. They found that during the Olympic Games, dioxin levels fell nearly 30% below the previous month's levels, and that concentrations fell by 70% from the previous summer's levels. Dioxin concentrations rebounded in the summers of 2009 and 2010, but they remained below the pre-Olympics levels. This improvement was consistent with national trends in air quality after the government instituted pollution-control measures in 2006.

The researchers found no significant relationship between weather conditions and pollution levels, suggesting that emission controls alone caused the change. But study author Qinghua Zhang, of the Chinese Academy of Sciences, cautions that such progress could be thwarted by recent growth in the number of incinerators, which produce dioxin as a byproduct of burning waste.