The ozone threat

Alternatives to banned ozone-depleting substances may jeopardise the effectiveness of the Montreal Protocol

Published: Monday 15 October 2001

A new range of substances to replace ozone-depleting substances like chlorofluorocarbons and hydrofluorocarbons, which are banned under the Montreal Protocol, are doing more harm than good. These alternative substances, such as n-propyl bromide and halon-1202, may also have the potential to damage the ozone layer. Although these alternative chemicals, used in products such as fire extinguishers and cleaning fluids, are being manufactured in small quantities presently, researchers at the United Nations Environment Programme (UNEP) worry that in the coming years they may be produced in increasing quantities. "I would urge countries to carry out immediate scientific assessments of these new chemicals and ban those that are shown to have real ozone-depleting potential," says Klaus Toepfer, UNEP's executive director.

Under the Montreal Protocol, countries are committed to a precise schedule for reducing and eventually phasing out their consumption and production of ozone depleting substances (ODS). A number of ozone-depleting substances have already been phased out in industrialised countries.

UNEP has estimated that the ozone layer and the ozone hole over Antarctica, which by September 2001 had extended to over 24 million square kilometers (an area about the size of North America), will recover by 2050. The ozone layer acts as an invaluable shield by blocking out the lethal ultraviolet radiation from the sun. The ozone layer's recovery has largely been a result of the banning and phasing out of existing ODS. But now, their alternatives have caused concern in the scientific community that they may negate the effectiveness of the Protocol.

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