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Environment

Ozone-Depleting Compounds On Decline In Atmosphere

Atmospheric Chemistry: Concentrations of two hydrochlorofluorocarbon compounds peaked around 2012

by Jyllian Kemsley
October 19, 2015 | A version of this story appeared in Volume 93, Issue 41

Chlorofluorocarbons and hydrochlorofluorocarbons (HCFCs) are valued as refrigerants and propellants. When they are released to the atmosphere, however, they destroy Earth’s protective ozone layer. Although an international treaty controls the use of such compounds, a study last year indicated that concentrations of some of them continued to increase through 2012. Follow-up measurements now indicate that concentrations of two HCFCs, CH2ClF and CF3CH2Cl, peaked around 2012 and have since steeply declined, with emissions dropping by as much as 50% in three years (Geophys. Res. Lett. 2015, DOI: 10.1002/2015gl064709 and 10.1002/2015gl065846). The compounds were studied by international teams led by Fabian Schoenenberger and Martin K. Vollmer of the Swiss Federal Laboratories for Materials Science & Technology. CH2ClF has been used to a limited extent in refrigerant blends, and CF3CH2Cl has no known industrial use. The researchers propose that the compounds are most likely produced and emitted as intermediates or by-products of manufacturing HCFCs and that the decrease is probably due to a change in the processes that make those HCFCs. Emissions from other sources would be unlikely to show the observed steep decline.

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Modeled annual global emissions of CF3CH2Cl show a steep decline in recent years, possibly because of changes in HCFC production. The reduction around 2009 might be related to the global financial crisis. SOURCE: Geophys. Res. Lett.
Graph of ozene-depletion compounds.
Modeled annual global emissions of CF3CH2Cl show a steep decline in recent years, possibly because of changes in HCFC production. The reduction around 2009 might be related to the global financial crisis. SOURCE: Geophys. Res. Lett.

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