Beyond the carbon sequestration issue, plants and trees have a positive impact on the air we breathe. As mentioned above, plants produce oxygen as a by-product of their existence in our environment. Its part of that wonderful symbiotic relationship that plants have with animals: plants give off oxygen as a waste product and we need oxygen to survive.
Urban Air Quality
Highways and vehicles produce a plethora of air pollutants. But we are learning that plants and especially trees have a much more positive impact on our air quality than we once realized. Studies (Coder, 1996) have shown the following air quality benefits of urban trees:
- A sixty percent reduction in street level particulates on tree-lined streets vs. streets with no trees;
- Reduction in nitrogen dioxide, sulfur dioxide, carbon monoxide, cadmium, chromium, nickel and lead levels;
- Reduction in noise by up to 50%;
Plants Reduce Energy Use
In addition, trees, plants and lawns have huge impacts on temperatures and energy use, especially in urban areas. A landscape lowers local air temperatures by transpiring water and shading surfaces. Because trees lower air temperatures, shade buildings in the summer, and block winter winds, they can reduce building energy use and cooling costs. The US Forest Service estimates that the evaporation cooling effect from one large tree is equivalent to the cooling produced by ten room-sized air conditioners! In a residential setting, well-placed trees can reduce energy use by 10-30% compared to a similar home on an open lot.