Ambient levels of atmospheric carbonyls in Beijing during the 2008 Olympic Games

The measurements of atmospheric carbonyls concentrations in Beijing were conducted from 12 July to 8 October, 2008, covering the periods of the 2008 Olympic Games and Paralympic Games. Six carbonyls, including formaldehyde, acetaldehyde, acetone, butyraldehyde, valeraldehyde, and hexaldehyde, were identified in all air samples. The total average concentrations of these carbonyls before, during, and after tra c restriction were (48.1 15.2), (36.6 14.5) and (23.4 12.3) g/m3, respectively. Compared with the period after tra c restriction, the distinct high concentrations of the carbonyls before and during tra c restriction were primarily ascribed to the remarkable contribution of photochemical reactions. With respect to our previous investigation in the summer of 2005, the reductions of formaldehyde, acetaldehyde and acetone during tra c restriction period were about 64%, 47% and 27%, respectively, indicating that the air cleaning actions adopted by the Chinese government for the two games were e cient. The lowest levels of atmospheric carbonyls and the extremely high composition proportion of acetone after the tra c restriction were mainly attributed to the long-term e ect of the control measures for the two games.