Trees reduce the greenhouse effect by absorbing carbon dioxide (CO2), one of the principal ‘greenhouse gases’, and by shading our homes and offices.
During photosynthesis, trees absorb CO2 from the air and use it to help make other compounds essential for plant growth and oxygen is released back into the atmosphere.
By shading our homes and offices, trees reduce the amount of electricity needed for air conditioning. Most of our electricity is produced by burning coal, which produces carbon dioxide that is released into the atmosphere. A shady tree is both directly and indirectly reducing the amount of CO2 in the atmosphere.
Carbon dioxide however, is not the principal air borne health risk of urban areas. CO2 is a problem gas in terms of climate change, but more health problems to residents are due to nitrous oxides and particulates from vehicle exhausts and factory emissions.
Nitrous oxides and particulates in the air can have serious health effects especially for children and the elderly, including respiratory and cardiac problems and even premature mortality.
|Softening building lines, absorbing industrial emissions, mitigating noise|
Numerous worldwide studies have shown that well planted urban forests can filter large amounts of particulate matter from the air. A recent study indicated that the urban trees of London removed between 800 and 2000 tonnes of particulates from the air each year. Research in the United States concluded that the trees of New York saved an average of eight lives per year by absorbing particulates.
The nitrous oxides from car exhausts and other gases in the air are removed when the leaves of a tree absorb the air through their pores. In 2008, a team of researchers at Purdue University in Indiana, showed that trees were capable of absorbing the dangerous nitrous oxides and converting them into useful amino acids for other plants to use.
Acid rain is a phenomenon caused by the oxides of sulphur and nitrogen reacting with the moisture in the air to produce rain drops that are acidic. When a tree absorbs nitrous oxides from the air it is helping to ameliorate the corrosive effect of acid rain in some regions.
|Not just beautiful!|
Trees can make urban areas healthier places in which to live.