Writing in the 22 April issue of Nature, Stephen A. Montzka of the National Oceanic and Atmospheric Administration’s Climate Monitoring and Diagnostics Laboratory in Boulder, Colorado and colleagues report on trends underlying the strong decline in ozone-depleting gases — chlorofluorocarbons (CFCs) and halons, collectively the halocarbons.
The majority of the observed reduction in atmospheric halocarbon concentration is due to the removal of just one substance – trichloroethane – which was widely used as a cleaning solvent. However, concentrations of other halocarbons have remained static or even increased. Consequently the author says that once trichloroethane has been eliminated, the downward trend in atmospheric halocarbons could slow down or stop.