How clean is the air we breathe outdoors? How does pollution
in the air affect the quality of land and water? How healthful is
the air in our homes and offices?
The air we breathe today is cleaner and more healthful than it
was decades ago. Since 1970, total national emissions of the six
most common air
pollutants have been reduced 25 percent. Remarkably, this improvement
in national air quality has occurred even while, during the same
30-year period, the U.S. Gross Domestic Product increased 161 percent,
energy consumption increased 42 percent, and vehicle miles traveled
increased 149 percent (Exhibit 1-1).1
Building on this progress, work remains to ensure steady improvements
in air quality. For example, certain areas of the country at times
exceed national health-based air quality standards. We have much
to learn about the levels of toxic air pollutants and the quality
of air indoors.
This chapter has three main sections: outdoor
air quality, indoor air quality,
and global issues. Each section tries
to answer two general questions: What are the current conditions?
and, What are the major contributors to change? Questions about
health and ecological effects are posed and explored for a number
of air quality issues. The chapter concludes with a section on the
limitations of the indicators to address these questions.
Exhibit 1-1: Comparison of growth measures and emission trends,
1970-2001
(Click to enlarge)
Chapter 1: Cleaner Air
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