The
Environmental Health Benefits of Building Shade through Community Trees
When we build shade we are
helping to conserve energy. Conserving energy reduces greenhouse gas (GHG)
and air pollutant emissions, which improves air quality and addresses global
climate change.
We all play a vital role in
helping to keep our natural environment healthy for future generations.
Air Pollution, Climate Change
and Our Health
Each day we burn fossil fuels
such as oil, gas, diesel and coal for our daily energy, electricity and
transportation needs. It is the burning of these fossil fuels that generates
air pollution and GHG emissions that contribute to climate change.
The Ontario Medical
Association estimates that air pollution contributes to an estimated 6000
premature deaths in Ontario each year.
The research tells us that:
More people die or are
admitted to hospital for heart and lung problems on days with elevated
levels of air pollution.
Health effects are found at
air pollution levels previously thought to be safe.
Air pollution may contribute
to the development of lung cancer and chronic lung disease
Climate change makes air
pollution and its impacts worse.
Beat Summer Heat!
Trees and built shade can
provide a cooling effect by lowering the temperature of the ground surface
and the surrounding air.
Climate change is happening and GHG emissions
are increasing in Canada. As GHG emissions continue to rise in our
atmosphere it is expected that climate change will have a significant impact
on our health, communities and the environment.
The 2007 4th
Intergovernmental Panel on Climate Change (IPCC) report concluded that
man-made GHG emissions have caused most of the globally average temperature
increases since the mid-20th century. The report states that the warming
effect of GHGs increased by 20 per cent during the past decade which is the
largest change observed for any decade in at least the last 200 years.
The IPCC report mentions that global average temperatures have climbed for 25
years with 11 out of 12 of the hottest years on record having occurred since
1995 (IPCC, 2007).
More Details on These Environmental Health Issues:
Benefits of Planting Trees on
Environmental Health
Community
trees are important because they help improve air quality and address global
climate change. For example, they help to reduce atmospheric carbon dioxide by
storing it or by reducing demand for heating and cooling (Centre for Urban
Forest Research, 2006, p. 2).
Tree leaves absorb carbon dioxide and other air
pollutants and replenish the air with oxygen for breathing. The American
Forestry Association found that in just one year, a mature tree absorbs 26
pounds of carbon dioxide and cleans up pollution created by a car driven 11,300
miles. That same tree also provides enough oxygen for a family of four to
breathe during an entire year. Over 80 years, the average Canadian tree absorbs
200 kg of carbon dioxide – plus ozone, nitrous oxide, particulate matter and sulphur dioxide (Tree Canada, 2005, pg 2).
There is evidence that certain types of trees absorb air pollutants from the
air. “It is also likely that trees and vegetation trap PM10 and PM2.5, thereby
preventing these particles from becoming re-entrained in the air. Trees and
vegetation also capture carbon dioxide and serve as “sinks” for greenhouse
gases, thus helping to slow climate change.
By providing shade, trees and
vegetation also help to mitigate the negative impacts associated with climate
change by reducing the “urban heat island effect” that occurs when pavement,
concrete, and buildings in urban areas absorb heat thereby heating the
surrounding air both day and night” (Sustainable Halton, 2007, p. 28).
Annual net reductions of carbon dioxide can be attributed to tree shade on
homes, buildings and other structures (Centre for Urban Forest Research, 2006,
p. 2). As a result community trees “lowers local air and building temperatures
through transpiration, shading, and reducing winter wind infiltration, thus
lessening the demand for cooling and heating and the formation of ozone” (Centre
for Urban Forest Research, 2006, p. 4).
