A new ozone-destroying chemical has been found in the earth's atmosphere by Australian scientists, throwing repair of the ozone layer into doubt. A firefighting chemical suspected of being used by the Russian military, halon-1202, has increased five-fold in the atmosphere over the past 20 years, according to a scientist with CSIRO atmospheric research, Dr Paul Fraser. It has been increasing in the atmosphere by 17 per cent a year over the past two years.