Air Quality

Transportation has a direct effect on air quality. As the charts indicate, highway pollution is responsible for a significant portion of air pollution. As you read the information below, consider the role that the city can play in reducing air pollution. As Phoenix continues to grow, what new challenges will the city face?

Highway Share of Air Pollutants Emitted, 1997

Greenhouse Gas Emissions and Global Climate Change

Greenhouse gases from human sources threaten to alter Earth’s atmosphere, since the planet’s ecosystems cannot absorb such elevated levels of these gases. Carbon dioxide (CO²) is one of the primary greenhouse gases emitted by humans.

The accumulation of greenhouse gases in the atmosphere can lead to global climate change (also called “global warming,” since one outcome is an increase in the average atmospheric temperature). The results of global climate change are potentially dramatic. Increases in atmospheric and oceanic temperatures might raise sea levels and alter associated weather patterns, which in turn could increase the frequency and severity of extreme weather events worldwide. Such changes might alter current patterns of land use and human activity, as well as ecosystems and natural habitats.

^{Source: Environmental Protection Agency. “Our Built and Natural Environments: A Technical Review of the Interactions between Land Use, Transportation, and Environmental Quality.” January 2001.}