Air Quality Re-leaf

Trees have a direct and profound effect on our air quality, and our quality of life. They clean our air, water, and soil; they improve our health and sense of well-being; and they enhance our economic future.

The scientific community and regional decision-makers are just beginning to understand that trees offer many solutions to environmental problems.  Trees are powerful, full-time, efficient air filters. Smart decision-makers know that cleaner air and greener cities attract business and people, which encourages prosperity. They are also aware that large areas of brick, glass and concrete create a “heat island effect”, causing a rise in temperatures of up to 12 degrees. Even a simple one degree rise in urban temperature will have a direct and negative effect on our air quality.

Current research provides important data regarding the positive and negative effects of trees on our air quality. A brief list includes:

• Trees that shade buildings reduce energy use and power plant emissions.

• Trees that shade streets and hardscapes reduce ozone formation.

• Trees can reduce wind speeds, which can increase ozone concentrations.  However, proper tree pruning and planting can help to increase air movement.

• Trees absorb carbon dioxide from our air (biogenic sequestration).

• Trees remove other gaseous air pollutants through their leaves.

• Trees also remove pollution by intercepting airborne particles on their plant surfaces (dry deposition).

• Trees do produce varying amounts of volatile organic chemicals (VOC’s) such as isoprene and benzene, which are precursors to ozone formation. But the overall benefits out-weigh this fact.

New research is being produced on a regular basis; and, it is clear that the many benefits of trees far outweigh any negative effect on our air quality. However, in order to maximize these benefits, plans must be established to strengthen regional and local forestry programs. These efforts should include a regional survey and analysis of our tree canopy cover as well as establishing management guidelines that lead to sound urban forestry practices in the future.

In order to effectively address air quality concerns using trees, the public must assume ownership of our urban forest and make a commitment to the proper management of this vital asset. In the future, as the public and private sectors are exposed to current research, we must become stronger stewards of our green infrastruc­ture. We all breathe the same air. By working together, we multiply our efforts, knowledge, and public support. The results have a positive impact on our environment in many ways.

According to National Forest Service research, larger trees are 60-70 times more beneficial than recently planted trees. As a result, tree conservation helps air quality today and tree planting will help in the future. These efforts will not resolve all of our air quality concerns but they are a critical part of the solution.

We have an obligation to leave our ecosystems in better condition than we found them. A great economic future is of little value without clean air. You do not have to be an environmentalist to be an “Airhugger”. Assuming ownership of our urban forest will provide a precious gift for our children that cannot be measured in dollars and cents.

To learn more about how trees improve our air quality:

Air pollution removal by urban trees and shrubs in the United States, by David J. Nowak, Daniel E. Crane, Jack C. Stevens, USDA Forest Service, http://www.fs.fed.us/ne/newtown_square/publications/other_publishers/OCR/ne_2006_nowak001.pdf

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