The production and global distribution of emissions of trichloroethene, tetrachloroethene and dichloromethane over the period 1988–1992

Emissions of trichloroethene, tetrachloroethene and dichloromethane have been estimated from audited production and sales data provided by members of trade associations in U.S.A., Japan and Europe. Together with an estimate of production and use in the former centrally planned economies, these comprise global data. In addition to the annual information, monthly data were collected for one compound: dichloromethane. These showed that there was no significant seasonal component to the emissions, either globally or when they were subdivided into regions or categories of end use. It is assumed that the other solvents show similar behaviour. The emissions were estimated in six geographical regions: North America, Europe, the Far East, the Northern Hemisphere tropics, the rest of the Northern Hemisphere and the whole of the Southern Hemisphere. Atmospheric concentrations calculated from the emissions of tetrachloroethene and dichloromethane are broadly consistent with observations, with some interesting differences which merit further investigation of potential additional sources and sinks. On the other hand, the calculated atmospheric concentration of trichloroethene is very much less than that observed, suggesting a significant additional global source of this compound.