The ozone hole over the Antarctic is growing at a rate that suggests it could be headed for a record size this year, Australian scientists say.
A study by Australian Antarctic bases attributed the development to colder temperatures in the stratosphere where the ozone hole forms.
"The growth at the moment is similar to 2000 when the hole was a record size," Australian Antarctic Division scientist Mr Andrew Klekociuk told journalists today.
Ozone is a protective layer in the atmosphere that shields the Earth from the sun's rays - in particular ultraviolet-B radiation that can cause skin cancer, cataracts and can harm marine life.
In 2000, NASA said the ozone hole expanded to a record 10.9 million square miles, three times the size of Australia or the United States, excluding Alaska.
"This is in contrast to the situation in 2002 when unusually warm conditions produced the smallest ozone hole since 1988," Mr Klekociuk said.
The ozone hole in 2003 presently covers all of the Antarctic.
The 1997 Kyoto treaty set in place a global process to reduce greenhouse gases which deplete the ozone layer, but the world's biggest polluter the United States has yet to sign.