BTS Home > Publications > Pocket Guide to Transportation > 2004

Chapter 6 - Transportation and the Environment

While transportation enhances the quality of our lives, it also generates undesired environmental impacts that can lead to human health problems and ecological damage. Overall, most transportation air emissions, such as particulates, have declined since 1980 despite significant increases in U.S. population, Gross Domestic Product, and vehicle-miles traveled. Only ammonia remains above its 1990 level.