Changes in stratospheric ozone concentrations and solar UV levels

Ozone is a major absorber of ultraviolet radiation in the atmosphere and as such protects the Earth from harmful shea wavelength solar radiation. Ozone depletion was first recognised over Antarctica, where it is at its most severe, but has since been identified over all but the equatorial regions of the globe. Corresponding increases in ultraviolet radiation are expected, and have been observed under clear skies at a few locations where monitoring facilities have been established for a sufficient number of years to enable a time series analysis. This provides some confidence in the inference of increased ultraviolet radiation at other locations, even though inter-annual variability and cloud precludes identification of seasonal changes in dose at present. The hearth implications of ozone depletion, mediated through increased ultraviolet radiation, depend to a large extent on the degree of exposure to the ambient radiation, and to the mode in which the biological effect is responsive to that radiation.