A study of the aetiology of accidents led to the development of two linked models: an interactive model of accident causation and an accident analysis procedure. The aim of the latter model was to identify relevant performance degradation areas with which to pinpoint the factors in the former model which lead to increased risk of accidents. An extensive literature search has identified cause-effect relationships between a range of industrial stressors (e.g. heat, noise and sleep loss) and the performance changes which occur. This information now allows the models to be used to explore particular situations.