Transportation and Air Quality

This chapter describes how transportation activities have a direct impact on the quality of ambient air. The proper phrase to describe the science that studies this impact is “transportation and air quality” rather than “transportation and air pollution.” For a majority of the substances that may be considered as air pollutants are, in fact, naturally present in the atmospheres. The predominant effect transportation sources have on the atmospheric air is to affect the quality of the ambient air. This chapter presents a broad outline of the underlying science and practices related to transportation air quality.