Widening ozone hole is as big as Europe
PARIS (AFP) Aug 30, 2005
The seasonal ozone hole over Antarctica has widened sharply this year, making
it the biggest hole since 2000 and the third largest on record, according to measurements
reported here on Tuesday by the European Space Agency (ESA).
Data sent back ESA's Earth-monitoring satellite Envisat showed the hole had
swollen to an area of 10 million square kilometers (3.86 million miles) in mid-August,
approximately the same size as Europe.
The hole is likely to expand further before reaching its maximum in September,
ESA said in a press release.
"This year's hole is large for this time of year, based on results from
the last decade. Only the ozone holes of 1996 and 2000 had a larger area at this
point in their development," it said.
Ozone, a molecule of oxygen, is a stratospheric shield for life on Earth,
for it filters out dangerous ultraviolet rays from the Sun that damage vegetation
and can cause skin cancer and cataracts.
But the protective layer has been damaged by man-made chemicals, especially
chlorine and chlorofluorocarbons (CFCs).
CFCs are an aerosol gas and refrigerant whose use was belatedly controlled
by an international treaty, the Montreal Protocol.
The size of the hole -- in effect a thinning of the ozone layer -- fluctuates
according to the season and prevailing weather.
High-altitude cloud formation, carrying traces of chlorine, is a big factor.
A single molecule of chlorine can break down thousands of molecules of ozone.
At ground level, ozone is formed by a reaction between road traffic exhausts
and sunlight, becoming a potentially dangerous irritant for people with respiratory
problems
====================================================================================
http://www.abc.net.au/news/newsitems/200508/s1449901.htm