A NEW ozone-destroying chemical has been found in the atmosphere, muddying repair efforts of the ozone layer. Halon-1202, a firefighting chemical suspected of being used by the Russian military, has increased five-fold in the atmosphere over the past 20 years, say Australian scientists. For the last two years, the chemical level has increased by 17 per cent every year.

Paul Fraser, a scientist with CSIRO atmospheric research, says that the rapid growth of halon-1202 has come as a surprise to him. "The international community will have to consider extending the ban on production of halon-1202 if we are to protect the ozone layer," he says. A variety of halons were widely used for firefighting until they were controlled by the Montreal Protocol, an international agreement that banned the use of halons and other chemicals in developed countries in 1994 and worldwide by 2004.

Halon-1202 has about half the ozone depletion potential of common chlorofluorocarbons, but had not yet reached a concentration to significantly damage the ozone layer. The gas was probably produced for military use in the former Soviet Union, says Fraser.