A study of the smoke problem in Des Moines establishes clearly that the smoke and gases emitted by its many power and heating plant chimneys have a harmful effect upon trees, shrubs and other vegetation. To a large extent, plants serve as good indicators of smoke contamination in a community.
In the immediate neighborhood of the smoke emitting establishments in Des Moines, only a few of the most resistant plants grow, all others being eliminated, A little farther away, where the smoke and gases are not so dense, some additional plants are found and so as the distance increases the number of plants increases until an area is reached where the air is not much contaminated and vegetation is normal. Around each large manufacturing establishment the vegetation may be mapped in belts of varying width, in each of which certain forms of plant life may be found, depending on susceptibility of smoke injury. In much the same way the entire area of Des Moines may be mapped in belts according to the influence of smoke injury on vegetation.
Bakke, A. L.
"The effect of city smoke on vegetation,"
Bulletin: Vol. 12
, Article 1.
Available at: https://lib.dr.iastate.edu/bulletin/vol12/iss145/1