This website describes a research project to measure volatile organic compounds emitted from species of trees and shrubs found in urban areas. The emissions are measured every several minutes, using new technology, to give a good picture of how different conditions (air temperature, sunlight, time of day) affect VOCs. Some VOCs can be ozone precursors. This research will recommend tree species that cities can plant to best combat air pollution. Topics include a description of the project and a section on trees and air quality. A page updated each month or so reports field and lab work on the project. There is also a glossary, profiles of community partners, and profiles of the scientists and students involved in the project.