ISLAMABAD, Sept 15: Ozone hole increased rapidly during the first two weeks of September from about 9 less than 10 million km2 (square kilometre) to approximately 19 million km2, according to the Antarctic Ozone Bulletin published to mark International Day for Preservation of the Ozone Layer.

As of mid-September, the ozone hole is smaller than it was in 2011, but larger than in 2010. This is based on observations from the ground, from weather balloons and from satellites together with meteorological data.

The Antarctic ozone hole is an annually recurring winter/spring phenomenon due to the existence of extremely low temperatures in the stratosphere and the presence of ozone-depleting substances.

It typically reaches its maximum surface area during the second half of September and the maximum depth during the first half of October.

The World Meteorological Organisation (WMO) says that it is still too early to give a definitive statement about the development of this year's ozone hole and the degree of ozone loss that will occur. This will to a large extent, depend on the meteorological conditions.

However, the temperature conditions and the extent of polar stratospheric clouds, so far this year, indicates that the degree of ozone loss will be smaller than in 2011 but probably somewhat larger than in 2010.

The ozone hole will most likely be smaller than in record year of 2006. The Montreal Protocol on Substances that Deplete the Ozone Layer, which was signed September 16, 1987, has prevented destruction of the ozone layer which protects Earth from the harmful ultraviolet rays of the sun.