Ozone killer confounds expectations.

Atmospheric concentrations of an ozone-destroying compound have risen at a surprising rate over the past decade, according to Australian scientists. These findings suggest that the protective ozone layer in Earth's stratosphere will take longer to recover than previously expected.

Measurements made in Tasmania show an increase in the concentration of halon-1211, a chemical used in fire extinguishers. Researchers had expected emissions of this compound to peak in 1988 and eventually decline, as industrialized nations phased it out in accordance with the Montreal Protocol of 1987. Since 1988, however, emissions have increased by 25 percent, estimates the Commonwealth Scientific and Industrial Research Organisation (CSIRO) in Melbourne.

Developing nations, particularly China, are most likely causing the rise in concentrations, says Paul Fraser of CSIRO. The Montreal Protocol allows developing nations to produce halon-1211 until the year 2010. According to Fraser, the additional emissions will delay the anticipated recovery of the ozone layer by up to 10 years.

Stephen A. Montzka of the National Oceanic and Atmospheric Administration in Boulder, Colo., and his colleagues have also detected increases in halon-1211 concentrations, although they calculate that emissions have remained constant.