Applications of the science of fluid mechanics to the new and expanding fields of industrial safety and environmental protection are discussed in this volume. The material is organized in accordance with the chain-of-events in real accidents, starting with the loss of containment of hazardous fluids, going on to the spreading and mixing processes in water or air, and ending with the damage loads caused by explosions, fires or toxic content. To develop solutions relevant to the wide range of problems considered, it is necessary to draw on material from various branches of fluid mechanics, i.e. from the engineering fields (aero- and gas- and hydrodynamics, hydraulics, heat transfer and two-phase flows) as well as from geophysics (environmental flows, boundary-layer meteorology). The relevant solutions are developed from the fundamental equations, but are kept simple for transparency and understanding. To achieve this, the simplifications offered by scaling, similarity and entrainment concepts are used extensively. Many of the solutions are novel but have been confirmed by laboratory experiments. The material in the book has been used as a teaching text on Master's level, but the content will be useful also for practising engineers and scientists engaged in safety and environmental impact. The problems considered have been encountered in consultancy work for industry and government agencies. The coherent presentation and the fundamental basis for analytical developments, makes the material accessible also to readers not acquainted with the field.