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Latest ozone assessment

The World Meteorological Organization and the United Nations Environment Programme have released the latest international assessment of the state of the ozone layer in the upper atmosphere. Their last review was in 1994.

The ozone layer is at threat because of releases of ozone-depleting compounds such as the chlorofluorocarbons (CFCs) and halons. Destruction of the ozone layer results in an increase in the amount of harmful ultraviolet radiation reaching the Earth’s surface. Consequent health effects include skin cancer and damage to crops and ecosystems is likely.

The Montreal Protocol was agreed in 1987, following the adoption of the Vienna Convention for the Protection of the Ozone Layer in 1985. If fully implemented, the targets set by the Protocol and later amendments should result in recovery of the ozone layer by the second half of the 21st century.

The new report, the Scientific Assessment of Ozone Depletion - 1998, represents the conclusions of over 200 scientists and confirms the effectiveness of the Montreal Protocol and subsequent amendments.

The 1998 report observes that:

  • the combined total loading of ozone-depleting substances in the lower atmosphere reached a maximum in 1994 and is now decreasing;
  • over northern polar latitudes, six out of the last nine boreal winter-spring seasons have seen ozone declines of 25 to 30 per cent below the 1960s baseline; and,
  • over the Antarctic, ozone losses in recent years have usually exceeded 50 per cent during September and October.

Without the Montreal Protocol and later amendments, the ozone decline would have been much stronger and would have continued for far longer. Even so, the ozone layer may not begin to recover until the year 2020.

There is concern that the illicit market in banned substances may erode the future success of the Protocol. The treaty permits a later phase-out of CFCs and halons in the developing world, and some nations such as Russia have not honoured earlier phase-out dates, so there is a remaining supply that can be smuggled into the industrialized world.

The Environmental Investigation Agency, based in London and Washington, reports that CFCs and halons produced in Russia, India and China are being supplied to the United States, Canada, the United Kingdom and other European countries where demand is still high. Developing nations are obliged to freeze production levels in July 1999 but that deadline may not be met by some of the major producers.

The British Antarctic Survey reports that ozone depletion has reached record levels during the southern winter of 1998.

Further information

UNEP’s OzonAction Programme aims to strengthen developing country capacity to phase out ozone-depleting chemicals. Activities include information exchange, publication of a quarterly bulletin, OzonAction, training, networking and support for country programmes.

OzonAction Programme, Tour Mirabeau, 39-43 Quai André Citroën, 75739 Paris Cedex 15, France. Fax: 33-1-44371474. Email: Web:

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