Decline in the concentrations of chlorofluorocarbons (CFC-11, CFC-12 and CFC-113) in an urban area of Beijing, China

During this study 352 whole air samples were collected in an urban area of Beijing between January 2005 and March 2007. The temporal variation of the concentrations of chlorofluorocarbons (CFCs: CFC-11, CFC-12, and CFC-113) in air in the Beijing urban atmosphere is presented and discussed. The weighted mean monthly values of these concentrations have been compared with the data from the north hemisphere. It has been concluded that, in the observed period of time, the mean enhancement of CFCs was relatively small, with increase of 10–15%, with respect to the global background. Change rate in concentrations of CFCs is −1.39, −1.04, and −0.16 pptv/month for CFC-11, CFC-12, and CFC-113, respectively. The tendency of the CFC concentration of the three compounds toward background values is observed to fall and indicates that limitation of emission of CFCs is taking effect, under the Montreal Protocol.