The air diffusion model as an urban planning tool

The air above a city is scarce and thus should be considered an urban resource. As a resource, air affects the urban population in several ways. First, the quality of this resource is important, it provides amenities to the urban dweller and enters into his site selection process. Second, because this mass is constantly in motion, it provides a diffusion mechanism through which externalities, or economic “bads”, are exchanged throughout the city.

In this article, we will develop a statistical air diffusion model that explicitly defines this exchange process. The model is then employed to examine two opposing theories of zoning justification—the property value theory and the planning theory. In examining the latter, the importance of air quality and its movement to the design and implementation of the comprehensive urban plan is emphasized.

“This urban system is no longer composed of separate, autonomous places with country in between but is a complete eco-system. A new urban ecology is in the making. Man is no longer able to step temporarily out of the framework of his own structuring or to move on elsewhere to escape the unforeseen consequences of his ingenuity, ruthless energy or folly”