The environmental benefits of urban green spaces are well known: greenhouse gas reduction, stormwater control, biodiversity conservation, and more.
But did you know that urban green spaces are also associated with human health and well-being? They promote the practice of physical and social activities, improve mental well-being, and reduce heat islands.(1-2) Whether through community gardening or walking in neighbourhoods or parks, people of all ages report experiencing relaxing or invigorating effects after going out into nature.
But when it comes to urban green spaces, the presence of trees seems to play a particularly important role. Let's take a look at what research is telling us about the effects of trees on human health.
What the research tells us
A recent systematic review of 201 studies looked at how urban trees may impact human health.(2) This review revealed that study designs and results are extremely varied. However, exposure to trees in urban settings is associated with multiple health benefits.
These benefits can be grouped into three main themes:
1. Harm reduction (41% of studies)
Urban trees, by removing a variety of air pollutants, reduce some of the negative health effects of pollution (for example, reducing the risk of lung cancer, respiratory problems and asthma, etc.). They reduce the risk of heat stroke, improve comfort in outdoor spaces during heatwaves, and thus reduce the risk of heat-related morbidity and mortality during heatwaves (a problem that particularly affects seniors). In addition, the shadow created by the foliage of the trees acts as a screen that blocks ultraviolet (UV) rays. Repeated and excessive exposure to UV rays can damage the skin, cause eye damage and increase the risk of skin cancer.
Some studies have also found an association between the presence of trees and a reduction in crime! However, it is not easy to explain such a phenomenon. Some researchers speculate that it may be related to the calming effect of vegetation, or that urban forests promote better social cohesion within a community.
In all cases, the benefits appear to vary depending on the species, size, location and state of health of the trees.
2. Capacity restoration (31% of studies)
Studies suggest that contact with nature or the sight of a forest landscape promotes better cognition and greater attention. Exposure to wooded environments can decrease anxiety, depression, anger, confusion and fatigue, with greater effects in people with higher initial stress levels. These benefits seem to be linked to biodiversity: a greater wealth of plant species promotes more mental well-being, in particular.
3. Capacity building (28% of studies)
Spending time in the forest, even for short periods of time, appears to enhance the immune system, as well as social well-being and a sense of community. Urban trees are linked to increased physical activity, resulting in decreased obesity and improved cardiovascular health.
Let's celebrate urban forests
Trees in urban areas play an important role in our health and well-being. But these trees sometimes have a hard time in urban environments. For example, trees often do not have enough space for it to root. This can cause stress and strain on the tree, as well as damage to sewers, curbs, roads, walls, and other man-made structures nearby.(3)
Participate in the greening of your communities. Several communities have joined the “Tree Cities of the World” program. This initiative aims to recognize cities and towns that are committed to ensuring that trees and urban forests are well maintained, sustainably managed, and celebrated as they should. Every year, towns and villages from around the world are giving citizens trees to plant on their property to help green their communities. Take part in these initiatives and help celebrate urban forests!