5 - Environmental Sustainability

While transportation enhances the quality of our lives, it also generates environmental impacts that can lead to human health problems and environmental damage. Overall, most transportation air emissions in the United States, such as particulates, have declined since 1980 despite significant increases in U.S. population, Gross Domestic Product, and vehicle-miles traveled. However, carbon dioxide emissions from transportation fuel use rose steadily until 2007 before decreasing in 2008.