Ozone layer recovery will be delayed by chemical leaks

Jun 27, 2017

By Fred Pearce

The healing of the ozone layer could be delayed for 30 years or more by rising emissions of a substance hitherto ignored by environmental regulators. Ironically, its principal use is as a feedstock to make “ozone-friendly” chemicals for air conditioners and refrigerators.

As emissions of CFCs and other ozone-eating chlorine compounds are curbed under the 30-year-old Montreal Protocol, emissions of another chemical called dichloromethane – also known as methylene chloride – have been rising, says Ryan Hossaini of Lancaster University, UK. They now total over a million tonnes a year, and concentrations of dichloromethane in the lower atmosphere have doubled since 2004.

The chemical, a volatile gas, has many uses, including as an industrial solvent and paint remover. The recent growth in its emissions – stemming either from production leaks or deliberate venting – are particularly tied to its increasing role in the manufacture of a hydrofluorocarbon called HFC-32, a widely used replacement for CFCs.

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