In the stratosphere, ozone performs an important role by absorbing harmful ultraviolet radiation from the sun and acting as a protective layer for life on earth. Sweden, the country of origin of the author, has been one of the leading forces examining the scientific evidence and ramifications of ozone depletion. This book provides a scenario of life under a thinning ozone layer and the effects of increasing UVR on people, plants and animals. It is written from the viewpoint of an interested lay person trying to find answers to questions about this important environmental issue. It may therefore appear superficial in content for some scientists expert in specific fields. However, the eleven chapters of this readable book do provide an interesting and accessible insight into the world of ozone depletion and related subjects.

The scene is set by a summary of the history and evidence for ozone depletion, particularly in relation to polar regions, which concludes that some of the `truths' presented to the mass media are far from clear-cut and that some warnings have been misguided because of the lack of understanding of the relevant biology. There follows a discussion of some of the basic science behind ozone depletion and the evidence for increased UVR at the earth's surface. By combining information from direct measurements with the results from radiation transfer models, the UVR dose, weighted for DNA damage, increased globally from 1979 to 1989, except in the tropics. The changes ranged from 5% at latitudes to 40% in Antarctica.

A consideration of the marine environment concludes that further knowledge is required in understanding the chemistry of the marine environment and the light-induced reactions inside the cell of plankton organisms. Subsequently, the plant ecosystem is considered with particular reference to agriculture, forests, grasslands and deserts. Here the conclusion is that most studies have concentrated on the effects of increased UVR levels on individual species and only 5% of all studies have been performed under natural field conditions. The long-term consequences of a changing light environment might be more subtle and work on the level of the ecosystem as a whole rather than on individual species. Other global issues such as the Greenhouse effect and atmospheric pollution are then explored.

Health issues (erythema and skin cancers) are dealt with under the title `Red alert'. A particularly striking image is an anguished sun worshipper roasting on a spit with the slogan `Vissa lär sig aldrig' (the book provides the translation!). Further health issues relating to immune response and the eye are then discussed. The health messages from these chapters are presented in a 12 point plan of advice to reduce sun exposure.

`Do Patagonian sheep need sunglasses?' is the title of a chapter that provides a limited insight into the effects of increased UVR levels on the animal kingdom. Being only four pages long, this chapter is perhaps the one for further scientific development. It deals with the aspects of eye disease in grazing animals, the declining population of some frog species and the effects of coral bleaching. The early reports that some Patagonian sheep were blinded by the effects of ozone depletion have been shown to be false and, although increased UVR levels may be implicated in some animal processes, other factors, such as global warming, may also play a role.

Finally, the pros and cons of the debate are summarised. Under the title `Shaky risk assessments' it is stated that much of the research and reviews on the effects of ozone depletion have concentrated on making risk assessments. Many of these have been moderated as new information and scientific controversy have surfaced and very few effects of increased UVR due to ozone depletion have been satisfactorily quantified. Non-melanoma skin cancer might be the exception, although heavily influenced by people's behaviour in respect to sun exposure. Much of the action towards research and policy in this area is based on a precautionary principle and the continuing integrity of the Montreal Protocol governing the phase-out of ozone depleting substances. The final sentence reflects this: `Will we breathe a sigh of relief if nothing visible happens and feel satisfied that we acted in time, for once?'