1.   Scientists have observed a drop in ozone levels over the Antarctic.

2.   Press reports revealed that ozone levels in the upper atmosphere fell during the past month.

3.   The W.H.O. safety standard for ozone levels is somewhere about a hundred.

4.   Government ministers admit that ozone levels are higher than anywhere else in the world.

5.   New evidence suggests that the most common incidence of asthma and bronchial complaints occur where ozone levels are highest, principally in south-east England.

6.   Thanks to wind drift, the highest ozone levels are often found in country areas.

7.   A new instrument for measuring ozone levels in the air has been developed by Austrian scientists.

8.   The northern hemisphere is experiencing record lows in ozone levels, according to data from the World Meteorological Organisation.