THE BIOLOGICAL EFFECTS OF OZONE DEPLETION

Thinning of the ozone layer is predicted to result in increased levels of ultraviolet (UV) B radiation at the earth's surface. This effect h as been confirmed by measurements made in relatively unpolluted areas such as Antarctica, the southern part of South America and at mid-to-h igh latitudes in the northern hemisphere. It has been harder to show i n populated northern latitudes because of a number of confounding fact ors, notably weather systems and low level ozone pollution. Although U VB forms only a small proportion of the UV spectrum it has potent biol ogical effects so that a small increase in penetration of UVB to the e arth's surface has profound effects on a wide range of life forms. Mos t attention has been paid to the effects of an increase in UVB on huma n health, particularly the effects on skin cancer, resistance to infec tious diseases and cataract formation. However, the effects of increas ed levels of UVB on other parts of the ecosystem, particularly on the primary producers in aquatic and terrestrial food chains, may be of ev en.