table of contents - Research and Innovative Technology ...

emissions rates, and discusses transportation
control measures (TCMs) and
their potential to mitigate
the impact of transportation
on air quality in metropolitan
areas.
About 80 percent of
the U.S. population lived
in 268 metropolitan statistical
areas (MSAs) in
1990. 1 The MSAs range
C H A P T E R E I G H T
TRANSPORTATION
AND AIR QUALITY:
A METROPOLITAN
PERSPECTIVE
METROPOLITAN AREAS EXPERIENCE THE MOST ACUTE TRANS-
PORTATION-RELATED AIR POLLUTION IMPACTS. COMMUTING,
SHOPPING, AND OTHER SHORT PERSONAL TRIPS IN HIGHWAY VEHICLES
CAUSE MOST OF THESE IMPACTS. THIS CHAPTER DISCUSSES AIR QUAL-
ITY TRENDS IN U.S. METROPOLITAN AREAS, ANALYZES FACTORS THAT
UNDERLIE THESE TRENDS, SUCH AS TRANSPORTATION ACTIVITY AND
1 The Bureau of the Census defines MSAs
as containing a central city of at least
50,000 population and all those surrounding urbanized counties that
are strongly linked with it.Large MSAs that include two or more adjacent
cities of over 50,000 population are designated consolidated
metropolitan statistical areas.
Between 1985 and 1994,
some of the fastest
growing metropolitan
areas (San Diego, Dallas,
Houston) had the highest
percentage reductions for
the primary air pollutants
from highway vehicles.
171
in size from almost 20 million people
(the New York-Northern New Jersey-
Long Island consolidated
MSA) to less than
200,000 people. (USDOC
1994a, 37, 39–41) A
growing proportion of
people live in large (population
over 1 million)
and medium-size (250,000
to 999,999) metropolitan
areas (see figure 8-1).
The central cities of MSAs are focal
points for various types of economic and
social interactions, such as commuting