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A Healthy Dose of Green

Key Message

A relatively modest investment in trees and forests can reap great rewards by reducing long term health care costs and increasing the health, well-being and productivity of current and future generations of Ontarians.


Trees Ontario. (2012). A Healthy Dose of Green. Toronto, Ontario: Author.


This paper contributes to our understanding of Ontario’s natural environment and its critical impact on physical and mental health. It is based on relevant research findings from the health and environmental disciplines that were compiled from print and online sources, including primary research papers from peer reviewed journals, government documents, books and other publications.
This paper acts as a catalyst for interdisciplinary research. It also supports a call to action to heavily invest in the recovery of ecosystems in Canada. By highlighting the links between human health and the health of both rural and urban forests, Trees Ontario hopes to increase support for tree planting initiatives.


Research shows evidence for positive associations between physical activity and the presence of green spaces, such as regional forests, in close proximity to residential areas.
More greenery in residential areas is linked to residents’ tendency to being more physically active and less overweight and obese.  Residents in environments with visible greenery and vegetation were 3.3 times more likely to take up frequent physical exercise than those in the lowest greenery category.

In Chicago conducted a study in a deprived neighbourhood in the city and observed that the amount of trees and grass in playgrounds is directly correlated with a higher frequency of play.29 Furthermore, children displayed more creative playing behaviour and had more contact with adults. (p 8)

The Ontario Medical Association (OMA) has developed the Illness Cost of Air Pollution (ICAP) model to estimate the health and economic impacts of smog in Ontario. 49,50 The 2005 report estimated that the number of hospital admissions related to air pollution exposure was approximately 17,000 per year while the number of emergency room visits was almost 60,000.51 By 2026, these rates are expected to jump to more than 24,000 and 88,000 respectively.

Evidence supports the links between air pollution, heart attacks, strokes and cardiovascular death.60 Evidence also suggests that there is an association between air pollution and irregular heartbeats, cardiac arrest and peripheral vascular diseases.61
Air pollution has also been linked to negative respiratory health with more than three million Canadians suffering from serious respiratory disease. (p 9)

Researchers at Columbia University have found that for every additional 343 trees per square km, asthma rates drop by 25 per cent in young children. (p 10)

Medical researchers have found a strong linear relationship between adult diabetes and smog—the higher the exposure to air pollution and smog, the higher the incidence of diabetes.

Several studies suggest that contact with nature may contribute to improved attention and function in children with attention deficit disorders. (p 11)

Numerous studies have shown that there is a direct correlation between the presence of trees and a decline in stress levels. (p 12)

Benefit Statements / Outcomes

Leadership Provided By:

  • Leisure Information Network (LIN)
  • Alberta Recreation and Parks Association

On Behalf Of:

  • Canadian Parks and Recreation Association (CPRAA)

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