Stratospheric ozone and health.

BACKGROUND Stratospheric ozone is being depleted and ambient ultraviolet (UV) irradiance is probably increasing. While remedial steps have been taken through the Montreal protocols, at best it will take some 90 years for stratospheric ozone concentrations to return to the levels existing in the 1970s. METHODS The evidence that these changes may have harmful effects on health has been reviewed. RESULTS The direct harmful effects are skin cancer, ocular damage and, possibly, immune suppression with an increase in infectious disease. Indirect, harmful effects resulting from climate change, changes in atmospheric chemistry, and changes in food supply may also occur. Beneficial effects are also possible but have largely escaped attention. Quantification of these effects is either uncertain or impossible at present and the outcomes for health in 50 years time can only be guessed at. CONCLUSIONS To understand better the health consequence of stratospheric ozone depletion, we need to know the quantitative relationship between ambient UV radiation and skin cancer, whether or not UV radiation really causes cataract and other ocular effects and what the quantitative relationships are, whether effects of UV radiation on immune function produce detectable health consequences, whether there are important beneficial effects of increasing UV radiation and, ultimately, what the balance of all these effects might be on health on a global scale.