Daily News Archive
From July 24, 2001

Choose the Right Tree to Decrease Air Pollution

According to the California Environmental Protection Agency's (EPA) Air Resources Board, it takes an informed selection and planting of trees to reduce urban air pollution. Air Resources Board Chairman Alan Lloyd said, "People plant trees for many reasons: to beautify their home, provide shade, and reduce energy bills. But, they might not be aware that certain trees can decrease air pollution and pollen counts. Necessary information is now available to choose the most effective smog and pollen reducing species."

Choosing a new tree should involve three main considerations: intended use, climate, and the tree's emission types and amounts. Tree emissions are classified as low, moderate, or high, based on the sum of the hourly emission rates of the chemicals isoprene and monoterpenes, compounds that play a role in tropospheric ozone formation and aerosol production.

When trees are selected with attention to what they emit, they can improve local cooling, reduce energy use, and slow the chemical reactions that lead to the formation of urban smog.

For more information about selecting appropriate trees, see Cal Poly San Luis Obipso's website SelecTree at http://selectree.calpoly.edu/.