Monday, June 22, 1998 Published at 17:51 GMT 18:51 UK
Ozone layer to recover by 2050
Industrial emissions have contributed to the depleted ozone layer
The ozone layer, which protects the Earth from ultraviolet radiation, will recover by the middle of the next century - if countries fully implement an international convention on the use of destructive chemicals, according to the World Meteorological Organisation.
The organisation says the thinning of the ozone layer will worsen for the next few years because of the high emissions of ozone-depleting chemicals in the last few decades.
But in its four-yearly report, published on Monday, it says that the trend can be reversed if the Montreal Protocol regulating their use is fully implemented.
The report, compiled by 200 scientists worldwide, underscores the efforts by countries over the past decade to reduce their emissions of ozone-depleting chemicals.
The Montreal Protocol - signed by 132 countries - includes the phasing out of the production of CFC gases contained in refrigerators and aerosols.
Firstly. the convention has yet to be fully implemented. The developing countries will only begin their phase-out of ozone destructive materials next year and secondly, the report's predictions are based on scientific models which can change.
The World Meteorological Organisation also points out that the ozone layer is currently in its most vulnerable state due to a high concentration of chemicals built up over the 1970's and 80's.
The report's authors say it will take another five years before these chemicals die out.
The report also says it will not be possible to detect any recovery in the ozone layer for another 20 years because of changing atmospheric conditions.