Ozone layer hole reaches record size

The "ozone hole" over Antarctica this year has matched the record size of 11.4 million square miles, the U.N. weather agency said Friday.

The area of the so-called hole - a thinning in the ozone layer during the South Pole winter - is the same as in the record year of 2000, according to measurements by NASA, said Geir Braathen, ozone specialist at the Geneva-based World Meteorological Organization.

But Braathen said of greater concern is that the amount of ozone gas particles remaining in the hole is even lower than in 2000, a measurement called "the mass deficit." According to the European Space Agency, the loss has been 39.8 megatons, he said.

"In a way this mass deficit is a better measure of how much ozone is depleted ... because it counts how many tons of ozone are lacking," Braathen told The Associated Press.

The thinner layer this year "will lead to more ultraviolet radiation on the ground," Braathen said.

Too much ultraviolet radiation can cause skin cancer and destroy tiny plants at the beginning of the food chain.

Thinning in the ozone layer - largely due to the chemical compounds chlorofluorocarbons, or CFCs, leaked from refrigerators, air conditioners and other devices - exposes Earth to harmful solar rays. Under a 1997 international treaty, most countries have agreed to reduce use of the ozone depleting chemicals, and scientists are predicting the ozone layer will eventually recover.

The hole has been forming in the extremely low temperatures that mark the end of Antarctic winter every year since the mid-1980s. Generally, the hole is biggest around late September

Measurements of the ozone layer over Antarctica by a European satellite have shown a record loss in the shield that protects the Earth from the sun's ultraviolet rays.

The ozone hole is nearly as wide as it was in 2000 and nearly as deep as it was in 1998, the European Space Agency said Monday. The record loss was reached because these dimensions occurred at the same time.

The ESA's Envisat measured a total ozone loss of 40 million tonnes, beating the record of 39 million tonnes set in 2000.

"Such significant ozone loss requires very low temperatures in the stratosphere combined with sunlight," ESA atmospheric engineer Claus Zehner said in a statement.

The ozone layer is the part of the atmosphere 25 kilometres up that acts as a shield protecting life on Earth from damaging UV rays, which can cause sunburns, skin cancer and cataracts. The rays can also harm marine life.

The ozone layer has decreased globally by about 0.3 per cent per year. The loss is seen as a hole over the South Pole because of atmospheric and wind conditions during the southern winter.