UNITED NATIONS, Sept. 16 (Xinhuanet) -- United Nations Secretary-General Kofi Annan on Tuesday called for greater efforts to save the world's radiation-shielding ozone layer.

　　In a message marking the International Day for the Preservationof the Ozone Layer, Annan said, "While we may be gratified with the progress that has been made through international cooperation,we must not be satisfied until the preservation of the ozone layeris assured."

　　He described progress made under the Montreal Protocol on Substances that Deplete the Ozone Layer, ratified by 184 countries,as "impressive," with scientists reporting a decline in depletion and the first signs of recovery following efforts to eliminate destructive man-made chemicals.

　　"However, we cannot be complacent," he warned. "The ozone layerremains depleted above the Antarctic and the Arctic, as well as inthe midlatitudes of both hemispheres of the earth.

　　Melanoma and other skin cancers kill 66,000 people each year, much of it due to the sun's ultraviolet radiation.

　　Several challenges remained to be met, Annan said. Developing countries must phase out the use of many ozone depleting substances within specified time schedules; illegal trade in chlorofluorocarbons must be curbed; alternatives to some current uses of methyl bromide must still be found; and more research is required on the relationship between depletion of the ozone layer and climate change. Enditem