Effects of urban green on the human health

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Effects of urban green on the human health

Paper “Biodiversity and Ecosystem Services”
Prof. Martin Hermy, prof. Bart Muys

Michiel De Bauw, Paulien Denis, Annelies Mertens, Julio Moguel Yanes,
Natalia Nieto Quevedo, Ward Standaert, Kobe Van Dijck, Margot Vanhecke

Table of contents

Summary……………………………………….………………………………p.3

1. Introduction.………………………………………………………………...p.3

2. Material and Methods………………………………………………………p. 5

3. Results………………………………………………………………………p.6

        3.1 Parks and greenways ………………….……………………………p.6

        3.2 Green roofs and rooftop gardens …………………………………...p.8

        3.3 Lane trees, pavement green and green walls ……………………...p.10

4. Conclusion…………………………………………………………………p.11

5.  References………………………………………………………………...p.12

6. Figures.……………………………………………………………….……p.14

Summary

This literature review focusses on the positive effects urban green elements can have on human health. Google and Google Scholar are used to obtain an overview of the different aspects of the subject, then more specific literature is found through Limo, the search engine of KU Leuven. Urban green elements are divided into three types: parks and greenways, green roofs and rooftop gardens, and lane trees, pavement green and green walls. For each of this type the benefits on different health threatening factors are assessed. All the groups benefit human health by reducing air pollution caused by traffic and by abating the urban heating effect. The first group is different because it influences the physical health of people. It enables and stimulates citizens to practice sports, like running. The second group differentiates itself because it can be used as an insulation for buildings, but has no specific positive effect on human health. The last group can reduce noise from pollution which also improves human health through stress reduction. To conclude, incorporating green elements in an urban environment influences human health in many ways.

1. Introduction

Over the last few decades, land use has been changing drastically. There is a gradual increase in the relative proportion of people living in urban areas. Between 2000 and 2050, the proportion of people living in urban areas is projected to rise from 46.6 to 69.6% (Lee and Maheswaran, 2011). Rapid and unsustainable patterns of urban development are making developing cities focal points for many emerging environment and health hazards. The growth of urban populations has a significant effect on the quality of global and local ecosystems, and the urban environment. This negative effect will play an increasingly important role in the health of city residents (WHO, 2016a).

Rapid urbanization has an impact on infrastructure, health and wellbeing. The health effects of urbanization are very broad: there is a change in the characteristic epidemiological disease profile and at the same time new diseases might appear. A denser population is a breeding hazard for diseases and these are spread more easily. The high density of motor vehicles locally increases the air pollution significantly (Chelala, 2015). This air pollution consists of greenhouse gases, fine particles and secondary pollutants like tropospheric ozone, which is toxic. In general, urban areas are dealing with higher concentrations of air pollutants (Ling et al. 2012). There has been a lot of research on the impact of air pollution on human health. Significant higher occurrence of heart attacks and lung diseases, including lung cancer, are observed in more polluted areas (Mabahwi et al., 2014). Some examples are CO, NO2 and ozone. Carbon monoxide (CO) is preventing oxygen uptake in the blood by a strong binding on the mitochondria. This is impeding the oxygen supply to the heart and so to the rest of the body. Nitrogen dioxide (NO2) can intensify lung infections. For children, it increases the risk of getting bronchitis and pneumonia. Ozone is a strongly irritating gas, affecting the lung airways by enforcing symptoms of long diseases. Besides the lungs, it causes injuries on the functioning of the cell respiration and eye irritation (Nurul Ashikin et al., 2014).  The most extreme problem is caused by particulate matter. The size of particles is directly linked to their potential for causing health problems. Particles smaller than 10 µm (PM10) in diameter cause the greatest problems. They penetrate deep into lungs and some may even get into the bloodstream. This gives rise to heart problems, respiratory symptoms and a decreased lung function. If there are a lot of concrete buildings, an “Urban Heat Island” might develop because of the heat storing capacity of the material. Excessive exposure to heat can have mild to serious consequences on human health (WHO, 2016b).

A report carried out by the World Health Organization (2016b), called the Global report on urban health: equitable, healthier cities for sustainable development, presents evidence that progress in urban health not only depends on the strength of health systems, but also on shaping healthier urban environments. A healthy population in urban areas is essential for creating economically competitive and inclusive cities. The report presents examples of effective initiatives by cities and nations around the world and subsequent successes. In Chapter 7, the authors talk about how to design healthier and more sustainable cities, which is off course a key factor in improving urban health.

An important aspect that has an influence on this improvement, is urban green. Green spaces like parks are crucial additions to cities. They offer the opportunity to be physically active and promote mental health. An advantage of trees and other types of vegetation is the provision of shade and the dissipation of heat by evaporation. There are examples of cities that adopt a policy, mandating green roofs for buildings of a certain height, in order to lower heat retention. All urban vegetation contributes to the capture of fine particulate matter. As can be concluded from the Global Report, researchers are realising the importance of urban green in the light of recent urbanization. However, not all positive aspects are assessed and not all opportunities are seized. In this report, we will list the different kinds of urban green and their influence on human health. Most studies report findings that generally supported the view that urban green has a beneficial health effect (Lee et al., 2010). We will try to illustrate the causal relationship, even though establishing this relationship is difficult, as it is very complex. In order to do this, we divided urban green into three separate categories, particularly parks, green roofs and lane trees, and pavement green, green walls and other green elements.

• 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:

1. General search:

1. 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.
2. We also had a look at the slides of the course “Urban Ecology and Green Management”, taught by Prof. R. Hermy.

1. Global idea:

1. 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).
2. 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.
3. We used our own knowledge to describe the health effects of urbanization and to asses which aspects of urban green we could address.

1.  Specific searches:

1. 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”, …
2. 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.

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