Can a Tree Capture Particulate Matter from the Air?

For years, certified arborists and urban foresters have learned the many benefits of trees. Energy savings are one of the foremost known benefits of trees as they shade building during the summer reducing the need for air conditioning and deciduous tress allow sunlight to reach structures during winter months, solar radiation decreasing the need for winter heating.

Another known benefit for trees are their ability to reduce storm water runoff and erosion, particularly during the winter months. Tree root systems bind soil particles and slow storm runoff from roofs and other impervious surfaces, trees act as bio filters, slowing storm and irrigation water runoff and allowing the water time to slowly percolate into the soil profile rather than run off into the street or storm drain system.  By forcing water to pass through the soil profile, rather than runoff into storm drain systems, the soil mass filters impurities before the water enters into streams, ponds and aquifers.

Birch Tree planting works as filter

A Birch street tree planting used for testing as a green filter to remove particulate matter from the air we breath

Trees also provide a benefits to the air we breath. Trees absorb carbon dioxide, one of the main greenhouse gases in our environment, and through the twin processes of photosynthesis and respiration, they produce oxygen. In the process, trees remove huge quantities of carbon dioxide from the environment and trap or sequester the carbon dioxide as carbon within the wood and roots of the tree. So not only do trees reduce greenhouse gases, they produce oxygen for us to breath and keep carbon locked up within the tree mass.

Yet another great benefit of trees are their ability to capture particulate matter within their leaf structure, thereby reducing the amount of particulate matter entering our homes and the air we breath

Particulate matter trapped in tree leaf

High resolution magnification shows particulate matter trapped on a Birch leaf.

I recently read an article that discusses how the leaves of the Silver Birch tree trapped metallic particles. These metallic particles are most likely the product of combustion and brake wear from vehicles passing by. It is a very interesting scientific article that tested the ability of a tree-lined streets and worked on quantifying how a “green wall” of vegetation acts as an air filter.

Trees surround us, in the urban landscape, the natural landscape, on our parks, rural communities.  Trees are everywhere which might be why they are so easy to take for granted.  Imagine your favorite street and most likely it has street trees lining the parkways.  Imagine your favorite park or outdoor setting and trees are no doubt in the picture.  Even when we do notice trees, most likely we appreciate tree aesthetics and beauty without even realizing the many “green” environmental benefits trees provide us.

Read the full article at Trees Capture Particulate Matter from Road Exhaust

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