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Today's Air Quality...
Trees
Dallas is proud to be home to the largest urban hardwood forest of any city in the country, the 7,000 acre Great Trinity Forest.
Not only are trees the longest living organisms on Earth, they are also extremely important to our health and the health of our city and planet. From the simple tasks of providing a place for children to play and climb or providing a bit of cool shade to the more important role of absorbing CO2
(a greenhouse gas) and releasing oxygen, we all rely on trees.
Trees also play an important role in the economic health and vibrancy of a city. Cleaner air and a greener city attract business and people, which encourages prosperity: the more trees around homes, businesses and along city sidewalks make for a higher value and quality of life.
Top 10 Tree Fun Facts
- One acre of trees absorbs six tons of carbon dioxide and puts out four tons of oxygen. This is enough to meet the annual needs of 18 people. (Source: U.S. Department of Agriculture)
- The net cooling effect of a young, healthy tree is equivalent to 10 room-sized air conditioners operating 20 hours a day. (Source: U.S. Department of Agriculture)
- Just one shade tree can intercept up to 4,000 gallons of rainfall each year and reduce runoff of polluted storm water. (Source: USDA Forest Service)
- Healthy mature trees can add an average of 10% – 15% to a property’s value. (Source: USDA Forest Service)
- One large tree can provide a day’s worth oxygen for up to four people.
- Trees properly placed around a building can reduce air conditioning needs by 30% and save 20 – 30% in energy used for heating. (Source: USDA Forest Service)
- A single tree can absorb one ton (2,000 pounds) of carbon dioxide over its lifetime. One acre of tree cover can compensate for automobile fuel use equivalent to driving a car between 7,200 and 8,700 miles.
- Living in a home surrounded by woods, meadows and/or other natural settings can increase the attention capacities of children and generally improve their mental health. (Source: Cornell University)
- Social scientists have found that the more trees and grass in the common spaces of inner-city neighborhoods, the more those spaces are used by residents. (Source: University of Illinois at Urbana – Champaign)
- Compared with apartment buildings that had little or no trees or vegetation, buildings with high levels of greenery had 53% fewer total crimes. (Source: Kuo and Sullivan – Environmental and Behavior, 2001)
Trees and Our Air
(provided by Steve Houser, Chair, Urban Forest Advisory Committee)
While we are probably aware that trees are an important component of the natural landscape because of their prevention of erosion and the provision of a specific weather-sheltered ecosystem in and under their foliage, trees have also been found to play an important role in producing oxygen and reducing carbon dioxide in the atmosphere, as well as moderating ground temperatures. They are also, of course, significant elements in landscaping and agriculture.
Trees have a direct and profound effect on our air quality, as well as our quality of life, in many ways. They clean our air, water and soil; plus they improve our health, sense of well being and our economic future.
The scientific community and regional decision makers understand that trees offer many solutions to environmental problems. One of our most pressing environmental problems in the North Texas region is Air Quality.
Trees are powerful, full time, efficient air filters. 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 affect 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 may help to increase air movement.
- Trees absorb carbon dioxide and other chemicals from our air (biogenic sequestration). The absorption of carbon is more of a global warming issue than an air quality issue.
- Trees remove ozone from the air through dry deposition but also add unstable organic chemicals (or VOC’s such as isoprene and benzene) which are precursor to ozone formation.
New research is being produced on a regular basis, but it is clear that the many benefits of trees far outweigh any negative effect on our air quality.
According to National Forest Service research, larger trees are 60-70 times more beneficial than recently planted trees. As a result, 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.
To find out more about trees in Dallas, visit the City of Dallas Urban Forest Advisory Committee web site and the City’s Park Department’s Urban Forest Information web.
