Effects of urban green on the human health

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- A park is an area of natural, semi-natural, or planted space set aside for recreation. The vegetation consists of herbaceous species, shrubs and trees.

- A green roof is a roof of a building that is partially or completely covered with vegetation. Since actual gardens are rather hard to find in cities, only rooftop gardens are considered.

- Lane trees and flora on pavements and walls are also important when assessing urban health. They have a large effect on the capture of fine particulate matter and toxicants.

2. Material and methods

A literary study was carried out by the authors. The following search scheme was used:

- General search:

- We used search engines like Google and Google Scholar to search for “urban green”, “urbanization”, “urbanization AND health effects”, “green city”, “green in cities”, “health AND city”, “urban ecology”, etc. The results were used to get a general impression of the subject and to look for references to interesting papers.

- We also had a look at the slides of the course “Urban Ecology and Green Management”, taught by Prof. R. Hermy.

- Global idea:

- We developed a more specific idea of what to write about after reading the Global Report on urban health by WHO (2016) and The health benefits of urban green spaces: a review of the evidence by Lee et al. (2010).

- We used the reference papers mentioned in Google searches as base to start our assessment. We concentrated on more global papers that could give us an idea of the health effect of urban vegetation. Some papers or websites were used as references in the introduction.

- We used our own knowledge to describe the health effects of urbanization and to asses which aspects of urban green we could address.

- Specific searches:

- Using the search platform Limo, the collections of all KULeuven libraries and other LIBISnet-libraries can be searched. Specific searches were carried out using the following key words: “physical activity AND health”, “health benefits parks”, “greenways AND health”, “greenways AND traffic accidents”, “parks AND health”, “green roofs”, “green roofs AND human health”, “green roofs classification”, “ecotechnology AND green roofs”, “thermal regulation AND green roofs”, “city temperature AND urban green”, “air pollution AND urban trees”, “air pollution AND pavement green”, “air pollution AND moss”, “urban green AND noise reduction”, …

- The references mentioned in the papers found through Limo were also used to gather more information. This allowed us to specifically use referenced papers, which is a good indication of their reliability.

3. Results

3.1 Parks and greenways

The health benefits of parks and greenways can be further divided into different categories. First the physical and psychological benefits will be discussed, then the indirect benefits.

Physical and psychological benefits

In cities, inhabitants don’t always live close to forests, nature reserves or other sources of nature. Therefore, parks are a good way to implement green, biodiversity and nature related recreational options inside a city. Having a park nearby stimulates people to go outside and exercise, thus increasing strength, endurance and flexibility, decreasing obesity and the symptoms of depression or anxiety and improving psychological well-being (Gies, 2016). A study by the American Journal of Preventive Medicine shows that a “creation of or enhanced access to places for physical activity combined with informational outreach” leads to a 48.4% increase in the frequency of physical activity (Kahn et al., 2002). According to Macaluso et al. (2015) an increase in physical activity leads to an increase in physical and mental health. It is thus clear that having a park nearby has a positive influence on human health because of an increase in physical activity.

Another form of urban green that is park related are the so called ‘greenways’. A greenway “is a strip of undeveloped land near an urban area, set aside for recreational use or environmental protection” (Oxford Dictionary of English[a]). A greenway can be a walking trail, a strip shaped park or an abandoned railroad. It is sometimes used to link two parks together or used as a traffic-free way of transportation. Greenways are exclusively for walking and (most often) cycling. They are popular for going to work or school in a safe, healthy and fun way. Having those trails nearby stimulates exercise as well. One of the major benefits of greenways is that walking and cycling are being separated completely from car traffic leading to less traffic accidents. This stimulates even more people to choose for this eco-friendly and healthier way of transportation. The opposite is also true, illustrated in Figure 1 (Dora and Phillips, 2000).

It is therefore important to provide enough greenways and safe hiking and cycling routes in a city. Another health benefit of parks and greenways are the social benefits. Parks are very popular to meet with friends, walk the dog and interact with others. It is a place to relax within the busy, always-working city. Greenways can connect friends and families, stores, schools and work environments. This connection is not car-based and therefor social interaction is very easy. When no greenway is available, transportation by car is stimulated, leading to a more asocial way of transportation (Dora and Phillips, 2000).

Indirect benefits

Other benefits of parks include those which affect human health in an indirect way such as improved air quality by dust removal and climate regulation.

These benefits can also be considered in other spaces such as green roofs and other kinds of urban green. The particularity of the parks is the massive artificial plantation with diversity of species that can establish an ecosystem at a large scale. At the same time, parks can provide a better and healthier environment for the people living in cities. Parks and greenways help to fight the air pollution that cause several health problems in urban areas around the world. Atmospheric pollutants can be absorbed by the foliar surface of the plants; therefore, urban green projects must study which plant species are optimal in function of their pollutant removal property and parks