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 has been confirmed by measurements made in relatively unpolluted areas such as Antarctica, the southern part of South America and at mid-to-high latitudes in the northern hemisphere. It has been harder to show in populated northern latitudes because of a number of confounding factors, notably weather systems and low level ozone pollution. Although UVB forms only a small proportion of the UV spectrum it has potent biological effects so that a small increase in penetration of UVB to the earth's surface has profound effects on a wide range of life forms. Most attention has been paid to the effects of an increase in UVB on human health, particularly the effects on skin cancer, resistance to infectious diseases and cataract formation. However, the effects of increased levels of UVB on other parts of the ecosystem, particularly on the primary producers in aquatic and terrestrial food chains, may be of even.