Combustion of fossil fuels accounts for 90% of our energy needs and leads to the release of pollutants to the atmosphere. This book describes the impact of these emissions upon the chemical cycles in the air, at both a global and local level. Photochemical smog and acid rain normally receive attention as localized and intermittent phenomena, but it is recognized that the global accumulation of trace species produced via man's activities could dramatically affect the world's future climate. It is essential that we should understand the fundamental physical and chemical features of the zones of the atmosphere in order to appreciate the nature and scale of pollution problems. Knowledge of the working modes of energy systems is a prerequisite for emissions control technology. The second edition has been revised and reorganized in response to the rapid development of research and knowledge in the past decade. Basic theory is developed to a considerable extent to make the contents accessible to the more general or student reader.