Vast forest fires in Indonesia last year have produced a large cloud of an ozone-destroying chemical, an international team of researchers claims. The agricultural fungicide methyl bromide has been targeted under the 1987 Montreal Protocol on ozone- depleting substances. In 1997 industrialised countries agreed to stop using methyl bromide by 2004. Developing countries agreed to phase it out by 2014. But a survey of the Indonesian island of Sumatra last November found that atmospheric levels of the chemical, released by the massive burning, had risen to 230 parts per trillion near the site of the fires. This is 10 times the level found over the sea.