ABSTRACT
Stacks discharging to the atmosphere have long been one of the methods available to industry for disposing waste gases. The concentration to which humans, plants, animals, and structures are exposed at ground level can be reduced significantly by emitting the waste gases from a process at great heights. This permits the gaseous pollutants to be dispersed over a much larger area and will be referred to as control by dilution. Although tall stacks may be effective in lowering the ground-level concentration of pollutants, they still do not in themselves reduce the amount of pollutants released into the atmosphere. However, in certain situations, tall stacks can be the most practical and economical way of dealing with an air pollution problem.
