The purpose of this book is to describe the basic mechanisms whereby pollution is transported and diffused in the atmosphere. It is designed to give practitioners an understanding of basic mechanics and physics so they may have a correct basis on which to formulate their decisions related to practical air pollution control problems. Since many theoretical and qualitative solutions are applicable in only a few situations, the emphasis here is upon seeing mechanisms in action so that one can quickly learn from observations. Consideration is given to the multitude of complexities of topography, building shapes, wind fluctuations, and diurnal variations of stratification. Chapters are titled: Pollution over Flat Country; Dilution: Formulae and Mechanisms; High Level Inversions; Ground and Valley Inversions; Wet and Coloured Plumes and Natural Pollution; Separation; Some Effects of Air Pollution (Smells, Health Misconceptions, Blackening of Surfaces, and Expansion and Corrosion); and Repercussions. Numerous photographs are used to increase observation skills and indicate why the complexities of the problem make every situation unique. (BL)