This is not good for life on Earth. The hole in the ozone layer over Antarctica has dropped by 30 % in size in 2007 if we compare it to 2006, as revealed by new data sent by the European Space Agency's Envisat satellite. 0.3 % of the ozone layer mass is lost annually, but fluctuations in its thickness occur throughout the entire year.

The hole in the Antarctica's ozone layer reaches the maximum size during September and October but drops back by the New Year, but scientists are not sure if this will also happen with this year`s smaller ozone hole.

"Although the hole is somewhat smaller than usual, we cannot conclude from this that the ozone layer is recovering already," said Ronald van der A, a senior project scientist at the Royal Dutch Meteorological Institute in the Netherlands.
The decrease of the Antarctica's ozone layer is of 30.5 million tons, compared to the record-setting 2006 loss of 44.1 million tons. In 2007, the ozone hole (areas where the ozone is less than 220 Dobson Units) is of 24.7 million sq km, about the size of North America.

A Dobson Unit depicts the thickness of the ozone layer in a column. An ozone column of 300 Dobson Units at 0� C and 1 atmosphere would be about 3mm thick.

"Natural variations in temperature and atmospheric changes are responsible for the decrease in ozone loss, and is not indicative of a long-term healing. This year's ozone hole was less centered on the South Pole as in other years, which allowed it to mix with warmer air," said van der A.

As the ozone breaks down at temperatures lower than -108o F (-78o C), the warm air protects the thin ozone layer located at 16 miles (25 km) above the ground. The prohibition of ozone destroying chemicals, like chlorofluorocarbons (CFCs), has not prevented the layer from thinning, despite the fact that the issue was widely accepted in 1985.

The ozone layer protects life on Earth from sun's harmful UV radiation, which in humans rises the risk of developing skin cancer and cataracts.