BBC Friday, December 4, 1998 Published at 17:18 GMT

Sci/Tech

Ozone hole just lasts

and lasts

Ozone damage will go on getting worse for some time yet

By Environment Correspondent Alex Kirby

The Antarctic ozone hole has set a new record. It

has lasted longer than in any other year - for nearly

100 days.

The World Meteorological Organisation, a UN

agency, says the hole measured 13 million sq km

for most of November.

The WMO says this is the first time since tracking

of ozone levels began in the 1970s that the hole

has measured more than 10 m sq km for so long.

Between 65 and 90 degrees south, the WMO

says, the average ozone level was the lowest ever

recorded for November.

Some good news

Overall, south of 60 degrees latitude, the ozone

destruction was about 30% worse than the

average for the last eight years.

The good news is that the hole in November was

barely half the size it had been in September.

It then measured a record 25 m sq km, two and a

half times the size of Europe.

At the end of September, according to the WMO,

ozone depletion was the greatest ever observed

for the time of year, and it covered a larger area

than ever before.

The previous record hole, in 1993, measured 22 m

sq km. The average over the past few years has

been about 20 m sq km.

The WMO says average

ozone levels over the

entire south polar area

during September were

about 45-50% below

normal.

But at higher levels,

between 14 and 22 km

above the earth, ozone

loss was 80-95%

The ozone layer protects

all life against the harmful

effects of the sun's ultra-violet radiation, which can

cause blindness and cancer.

New level of damage

While humans can take some precautions against

exposure, there is little to be done for animal or

plant life short of stopping the damage to the

ozone layer.

UV radiation is known to damage plankton, the

microscopic organisms which are at the base of

the marine food chain.

Scientists at the

University of Plymouth

have reported that the

reproductive cells of

plankton appear to be

several times more

sensitive to UV radiation

than mature cells.

They say that 'the

ecological significance of

elevated UV(B) exposure

in the marine environment

may be seriously underestimated'.

Trouble in store

The ozone is being destroyed mainly by

chlorofluorocarbons (CFCs), gases which used to

be widely used in refrigeration and aerosols.

Their use is now banned in developed countries,

but the developing world has until 2005 to phase

them out.

Because they are so long-lived at high altitudes,

CFCs emitted years ago will go on causing

damage for a long time to come.

There is even a thriving black market trade in

smuggling contraband CFCs across frontiers.

Other ozone depleters include halons, used in

firefighting, and the fumigant methyl bromide.

An international agreement on protecting the

ozone layer, the Montreal Protocol, was signed in

1987.

The WMO says there are signs that the protocol is

beginning to have an effect. But it will take at least

until the middle of the next century before the

ozone has returned to normal.

Scientists expect things to go on getting worse for

some years yet before they start to improve.