Overview

The subject of "Air Pollution", which results from "Emissions from Buildings" in the first place, is a subject in its own right, and many books are devoted solely to its study. At one time the government in the UK had a laboratory (Warren Spring) entirely devoted to its study. The subject can only be touched on lightly in a book on Building Aerodynamics; the reader who wants an in-depth study should start with such works as "Atmospheric Diffusion" by Frank Pasquill or one of the many books by Dick Scorer. But, for the reader basically interested in buildings and their environment, this chapter will explain the study of emissions which can be integrated with the other aerodynamic studies carried out on buildings.

A distinction can be drawn between the emissions from ventilating systems and emissions of combustion products, kitchen outlets and gases from laboratories, hospitals and other specialist sources. The purpose of a ventilating system is to replace the oxygen supply and to remove minor smells and odours that are produced in the normal way of life. The other emissions can be divided into three categories, toxic, annoying and unnoticeable.

The effect of the wind on the plume is the first concern. When there is no wind at all, the plume will rise vertically until it loses all its vertical momentum and buoyancy, and then the heavier-than-air content of the plume will start to fall and will arrive at the ground at the site of the chimney. If there...