Visualizing Environmental Science

Population and Urbanization 183

Courtesy Rubinoff Company

Environmental Benefits

of Urbanization

Although our previous discussion may suggest that the

concentration of people in cities has a harmful effect

overall on the environment, urbanization does have the

potential to provide tangible environmental benefits that

in many cases outweigh its environmental problems. A

well-planned city actually benefits the environment by re-

ducing pollution and preserving rural areas.

One solution to urban growth is compact develop-

ment, which uses land efficiently. Dependence on mo-

tor vehicles and their associated

pollution are reduced as people

walk, cycle, or take public tran-

sit such as buses or light rail

systems to work and shopping

areas. Because compact devel-

opment requires fewer parking

lots and highways, more room

is available for parks, open

sulfur oxides, carbon oxides, nitrogen oxides, and vola-

tile organic compounds. Urban areas in developing na-

tions have the worst air pollution in the world. In Mexico

City, for example, the air is so polluted that schoolchil-

dren are not permitted to play outside during much of

the school year. Although progress has been made in

reducing air pollution in highly developed nations, the

atmosphere in many of their cities often contains higher

levels of pollutants than are acceptable based on health

standards.

Cities affect water flow because they cover the rainfall-

absorbing soil with buildings and paved roads. Storm sys-

tems are built to handle the runoff from rainfall, which is

polluted with organic wastes (garbage, animal droppings,

and such), motor oil, lawn fertilizers, and heavy metals.

Most U.S. cities treat or divert urban runoff before dis-

charging it into nearby waterways. In many cities, how-

ever, high levels of precipitation can overwhelm these

efforts, resulting in the release of untreated urban runoff.

When this occurs, the polluted runoff contaminates water

far beyond the boundaries of the city.

compact

development

Design of cities in

which tall, multiple-unit

residential buildings

are close to shopping

and jobs, and all are

connected by public

transportation.

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Pittsburgh’s first brownfield redevelopment project, Washington’s Landing at Herr’s
Island, today features upscale housing, recreation, and commerce. The neighborhood
was formerly the site of sawmills, stockyards, soap works, and the Pennsylvania
Railroad.

Why are many developers reluctant to

redevelop brownfield areas?

Think Critically