Repeat performance

The ozone layer over the Antarctica was nearly as severely depleted in November last year as it was in 1993, when it reached a record low, reveal several airborne and space sensors.

According to Richard Bevilacqua of the US Naval Research Laboratory, ozone levels began falling in May 1994, and reached their lowest level in October 1994, but its concentration is now beginning to recover slowly. Scientists at NASA and the National Oceanic and Administration have also recorded similar results.

Ozone levels dropped below 100 Dobson Units (DU) -- a measure of thickness of the ozone layer (100 Dobson units equal 1mm) -- over the centre of Antarctica. The largest hole was over 24 million sq km in 1992, but the lowest average level of ozone was recorded in 1993 when it was only 96 DU thick.

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