Anthropogenic emissions of long-lived halocarbons, namely chlorofluorocarbons (CFCs), hydrofluorocarbons (HCFCs), methyl chloroform (CH₃CCl₃), and carbon tetrachloride (CCl₄) represent the largest source of atmospheric chlorine. A large fraction of the end uses of these compounds have resulted in the dumping of chlorine-containing equipment and materials in waste sites from which leakage is now occurring. Previous work at two US landfills in Eastern Massachusetts has shown that landfill gas emissions may be a significant source of atmospheric chlorine. This idea was further explored during a field campaign in southwestern Britain in July/August 2004. Flask samples were taken at several landfills with varying waste composition, landfill age, and basin geology. The flasks were analyzed for CFC-12, CFC-11, CFC-113, CH₃CCl₃, and CCl₄ using GC-ECD. Results will be discussed for the US and UK landfills sites.