Most people in the world live in cities

World US Mexico

% Urban 45% 76% 75%

change

since 1965 +10 +5 +20

Reasons for Growth of cities:

1. Industrial Expansion is Urban
Ä Job creation in cities
Ä RuralãUrban migration

2. Social Services are Urban biased
Ä Health care
Ä Education

3. Political Power of urban developers over rent-producing governmental powers

Two Types of Environmental Concerns are associated with cities:

1. Exposure of vast numbers of people to the concentrated contaminants which are, inevitably, concentrated in urban areas

Ä SF Women and Breast Cancer
Ä Cincinnati Water Contamination


2. The populace of cities utilizes resources in amounts far in excess of local ability to produce, replenish, or reprocess them.

Ä Los Angeles and Mono Lake
Ä Chicago Sewer System
Ä Air Pollution

Mexico City: a Topographical Error

Mexico City is a Natural Basin surrounded on all sides by high mountains.

Ä rain collected into large, shallow
lake

Ä air inversions

Mexico City:

Principal Air Contaminants in mg/m3

Allowable Mex City

SO2 40-60 100

NOx 150 150

O3 120 >300

CO 20 >30

Particulates 90 >200

Lead 1 1.5