NASA satellite images show that at its largest the hole reached towns in South America while less depleted air, outside its rim, brushed southern Tasmania. Ozone in the atmosphere shields the Earth from ultra-violet radiation.
Ozone depletion increases the risk of skin cancer, among other dangers.
At its greatest extent on September 12, the hole measured 32.9 million square kilometres, or more than three times the area of Australia, according to the calculations of Dr Paul Lehmann of the Australian Bureau of Meteorology. This was several million square kilometres more than the previous record in 1998. The World Meteorological Organisation said in a bulletin the hole was the deepest on record. It warned that such deep ozone holes could persist as a trend well into the future. The hole is now beginning to subside as analysts ponder whether its size this year is due to a normal annual variation of the weather, or to climate change.