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Trees Are Essential To Your Health

Trees have provided artists and poets with inspiration for centuries. The powerful health benefits of trees and the natural environment have also been recognized in an intuitive way by many writers.

In 1862, Henry David Thoreau wrote an essay for The Atlantic Monthly that described the effects of trees on his personal well being, “I cannot preserve my health and spirits unless I spend four hours a day at least – and it is commonly more than that – sauntering through the woods and over the hills and fields, absolutely free from all worldly engagement.”

Although few of us have the luxury of a four hour daily nature break, we can achieve many benefits from frequent contact with trees.

A growing body of scientific evidence demonstrates powerful and practical benefits of living in an environment where trees are plentiful.

Trees Can Scrub Pollution From The Air

Trees cleanse the air of pollution that occurs in the modern urban and industrial environment. They do this by absorbing a variety of poisons through the pores in their leaves and by scrubbing the air with their bark. Trees remove harmful substances such as sulfur dioxide, ozone, nitrogen oxides, and particulates from diesel exhaust. All of these compounds cause serious cardiac and pulmonary problems

Trees can also remove dangerous heavy metals from the air we breathe. One study estimated that during one growing season a single sugar maple near a road removed 5200 mg of lead, 140 mg of chromium, 820 mg nickel, and 60 mg of cadmium.

Trees Can Help To Reduce Global Warming

Trees remain an under-appreciated asset in the process of CO2 reduction. Like all plants, trees convert carbon dioxide into oxygen, and they do so in a massive way.

Through the shade they provide trees dramatically reduce surface temperatures, a fact which is readily appreciated by anyone who has ridden a bicycle in the summer and has been refreshed on a shady section of the road.

Trees that shade houses from the Summer sun can reduce air conditioning costs by as much as 50%. In addition to saving the homeowner money, this cuts down on energy needs and reduces the utilization of fossil fuels for power generation.

It has been estimated that if every family in America planted one tree, this would lead to an annual reduction of one billion pounds of CO2 in the atmosphere.

Deforestation is, in my opinion, one of the most critical issues facing the global environment. There is both good news and bad news that has been reported recently on the topic of deforestation.

First the good news. Many of the previous methods used to calculate the number of trees on the Earth’s surface underestimated the true number of trees. More precise methods from a study led by Yale University now show that there are three trillion trees on the Earth’s surface. This surpasses previous estimates by over seven times!

Unfortunately there is also bad news. The same Yale study estimates that the total number of trees has declined by 46% since the dawn of human civilization. Deforestation continues at an alarming pace is much of the world.  Every year we lose an area of forest the size of New York state. In addition to leading to increased CO2 levels, deforestation often leads to soil erosion, and the destruction of vitally important habitats.

Any efforts that purport to decrease global warming yet diminish the surface area of the earth covered by tress or other natural vegetation are inherently short-sighted. It would not make sense, for example, to cut down a forest in order to set up an array of solar panels. Although this might seem to be a ridiculous example, the subsidies offered for certain areas of green energy production are so huge, that people might engage in counter-productive activities just to capture the economic benefits. Well-intentioned laws often have unintended consequences.

Trees Make Us Healthier

The presence of trees in our day-to-day environment makes us healthier.

Many suburbs of Chicago were devastated by the emerald ash borer. There is no question that the physical beauty of many areas was reduced by the destruction of large sections of mature trees. The loss of trees may also be associated with increased cardiovascular  and pulmonary illness.

One study looked at various counties in 15 states in order to see if there was any connection between the loss of trees and cardiovascular and respiratory illness. Areas with extensive tree destruction were associated with additional 15,080 cardiovascular deaths and 6113 deaths from respiratory illness. Although it is always difficult to prove a direct connection between an association and a direct cause-and-effect, it is worth looking further into this issue.

In another study scientists mapped tree density in Toronto using high-resolution satellite images and other tree data and looked for a correlation with cardio-metabolic disease, mental illness, and self-perception of health and well-being. The study was designed to eliminate the possibility that social  and economic disparities might be the cause of any differences. People in neighborhoods with a high density of trees reported fewer episodes of mental illness, decreased cardio-metabolic disease, and increased self-perception of overall health.

As a plastic surgeon, I am constantly seeking ways to make my patients’ recovery from surgery as easy and comfortable as possible. Trees can help patients make a smooth recovery from surgery. A landmark study from the 1970’s compared the recovery from gallbladder surgery between two groups of patients. One group recovered in rooms that faced a brick wall, the other faced a cluster of trees. The patients with the view of trees had a faster recovery, experienced less pain and were less likely to be depressed.

Trees Help Our Children Learn Better In School

Trees also provide a benefit to children. A higher level of greenness around schools is associated with reduced levels of traffic-related air pollution both outside the schools and inside the classrooms.

Increased levels of traffic-related air pollution can have direct effects on the ability of students to learn.  A study from Barcelona, Spain showed that schools with a high level of greenness in the surrounding areas (hence less pollution) experienced greater increase in working memory and decreased inattentiveness compared to schools in less green environments.

Trees Should Be Available For Everyone

As a species, humans have only lived in cities for a few thousand years.  Although there are economic, intellectual, and social benefits to modern urban existence, these benefits may be severely offset if we lose our connection to nature.

The great urban planners of the 19th century understood the importance of green space and trees for citizens of all social classes.  Daniel Burnham’s plan for the city of Chicago protected the lakefront and extended parkways and greenbelts into areas far from the lake.  Frederick Law Olmsted is responsible for the beauty of  New York City’s Central Park and Chicago’s Jackson Park. The forests present in the Cook County Forest Preserves came about because social visionaries were able to look beyond the economic benefits of developing every square inch of land.

Particularly in urban areas under budgetary pressure, it may be expedient for some politicians to neglect or even cut down trees.  This can reduce the line item for tree maintenance on the city budget.  This is enormously short-sighted, since the health and aesthetic benefits of trees are lost, particularly by the poorest citizens.

I would argue that humans have a fundamental connection to trees that may be linked to our biology similar to the way that fish are linked to an aquatic environment.  Just as the ocean provides an environment that enables fish to “breathe”, trees purify our air and contribute directly to our health and well-being.

by © Terry W. Eggers/CORBIS