Page 59 - Fundamentals of Air Pollution

3

Scales of the Air

Pollution Problem

Problems of air pollution exist on all scales from extremely local to global.
These are divided in this chapter into five different scales: local, urban,
regional, continental, and global. The local scale includes up to about
5 km. The urban scale extends to the order of 50 km. The regional scale is
from 50 to 500 km. Continental scales are from 500 to several thousand
km. Of course, the global scale extends worldwide.

I. LOCAL

Local air pollution problems are usually characterized by one or several
large emitters or a large number of relatively small emitters. The lower the
release height of a source, the larger the potential impact for a given release.
Carbon monoxide from motor vehicles will cause high concentrations near
roadways. Any ground-level source, such as evaporation of volatile organic
compounds from a waste treatment pond, will produce the highest concen-
trations near the source.
However, large sources that emit high above the ground through stacks,
such as power plants or industrial sources, can cause local problems, espe-

35