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Monday, 10 March 2014

Ozone-Depleting Gases Are Being Released From An Unknown Source, Researchers Say

The Almagest

Four new man-made gases associated with loopholes in the ozone layer have been recently identified, although the Montreal Protocol called for a total ban of ozone-depleting gases by 2010.

Researchers from the University of East Anglia say they found evidence of four new gases that can destroy ozone and are getting into the atmosphere from an unidentified source.

The gases consist of three new chlorofluorocarbons (CFCs) and one new hydrochlorofluorocarbon (HCFC). Invented in the 1920s, the CFC gases were widely used in refrigeration and as aerosol propellants in products like hairsprays and deodorants.

Because of the growing ozone hole, the production of chlorofluorocarbon (CFC) gases has been restricted since the mid 1980s. The precise origin of these new substances has not been explained yet, researchers say.

Lying in the atmosphere, between 15 and 30km above the Earth’s surface, the ozone layer blocks harmful UV rays, which cause cancers in humans and reproductive problems in animals.

“Our research has shown four gases that were not around in the atmosphere at all until the 1960s which suggests they are man-made,” said lead researcher Dr Johannes Laube.

The scientists discovered the gases by analysing polar snow pack, as air extracted from this snow shows what was kept in the atmosphere up to 100 years ago.

Analysis of modern air samples collected at Cape Grim in Tasmania showed also that about 74,000 tonnes of these gases have been released into the atmosphere.

One of those gases has been listed as an “agrochemical intermediate for the manufacture of pyrethroids”, a type of insecticide that used to be widely used in agriculture. Others are intermediaries in the production of widely used refrigerants and in the production of solvents used to clean electrical components.

“The concentrations found in this study are tiny. Nevertheless, this paper reminds us we need to be vigilant and continually monitor the atmosphere for even small amounts of these gases creeping up, either through accidental or unplanned emissions,” said Prof Piers Forster, from the University of Leeds.

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