The Antarctic ozone hole is bigger than it has ever been at this time of the year, threatening populated regions of South America and New Zealand with harmful levels of ultraviolet radiation. Last year's hole was smaller than those recorded over the previous decade, leading to hopes that the protective layer in the upper atmosphere was beginning to recover from its destruction by human-made chlorofluorocarbons (cfcs). But early observations reported to the uk-based British Association for the Advancement of Science show that the hole, which appears every southern spring, is returning with a vengeance.

Alan Rodger, who runs the British Antarctic Survey's ozone monitoring programme, says: "Last year's smaller hole should be regarded as exceptional and clearly a one-off event. It had