UV Radiation and human health effects

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Abstract
In this chapter we describe some of the potential effects of increased UVB radiation, due to stratospheric ozone depletion, on human health. These effects include immune suppression, and its role in skin cancer and infectious disease development. We describe also the association between UVB and cataract development. The concern about increased UVB radiation and its impact on human health stems from reports of continuous ozone depletion. For example, the high chlorine levels presently in the stratosphere predict that ozone depletion will last through most of the next century. Currently, conservative estimates indicate that global ozone in the Northern hemisphere, from 30–60° N latitude, has been decreasing at a rate of between 0.25% and 0.3% per year, using 1970 as the baseline. Thus, we are already in a deficit mode of about 4 to 5% within that latitude range. For higher latitudes the losses are greater, in the order of 10% or more. More recent regional intermittent measurements, e.g. from Siberia and Canada, have indicated even greater ozone losses, with some occasions showing depletions of as much as 40%. Generally speaking, for each 1% decrease in stratospheric ozone there is an estimated 1 to 2% increase in UVB radiation transmitted to the earth. How much of this UVB radiation is attenuated by clouds, rain and pollution (e.g. tropospheric ozone is increasing) is a question of considerable interest and debate as UVB attenuation by such factors can be significant. However, it is clear that not every day is cloudy, polluted, or rainy, all the time over every populated area. Thus, the exposure of people, plants, animals and marine organisms to increased UVB radiation is inevitable. Some changes in human health, of the types described, can therefore be expected to occur over the coming years.