action has been taken, the benefits far exceed the costs.
Significant progress has, for example, been made in
reaching the internationally agreed goal of the Montreal
Protocol to protect the stratospheric ozone (ozone in
the upper atmosphere) layer. A drastic reduction in both
the production and use of ozone-depleting substances
(ODS) has been achieved, resulting in a 31 per cent
improvement in ODS indicators at mid latitudes since
1994, and the predicted avoidance of 22 million cases of
cataract for people born between 1985 and 2100 in the
United States of America alone.
For other issues, such as the reduction of indoor and
outdoor PM and emissions of sulphur and nitrogen
compounds, progress has been mixed. Tropospheric
ozone (ozone in the lower atmosphere) remains a
significant problem and is proving difficult to address.