A walk in the park: how green spaces can help mental well-being and more

People | Human Health

By Laura Butula, Kingfisher Writer

Published December 17th, 2021

Humans have a strong connection with nature, and there is plenty of evidence validating the positive effect of urban green spaces on human health and mental well-being. Here, we explore how green spaces alleviate negative emotions associated with pandemic isolation, racial health disparities, PMS symptoms, and air pollution.

Whenever people feel anxious or restless, they often go outside and take a 30-minute walk outdoors. This is a common stress-release practice; in fact, many individuals are strong advocates of this regime. It may be that the key equation for contentment is as follows: happiness equals natural environment (e.g., green spaces) plus physical activity.

Zrinjevac Park in Zagreb, Croatia | Zagreb ♡ You / Flickr

Green spaces can be defined as open spaces with natural elements located in urbanized areas. Parks, playing fields and recreational areas all fit this description. Over the past few decades, there has been a surge in evidence validating the physiological, psychological and social benefits of green spaces, as is the focus of this article.

For example, it has been demonstrated that green spaces affect mental well-being, symptoms of premenstrual syndrome (PMS), air pollution levels, and racial health disparities. All of these interesting influences will now be discussed.

‘Over the past few decades, there has been a surge in evidence validating the physiological, psychological, social, and economic benefits of green spaces.’

Notably, the World Health Organization (WHO) supports the socio-ecological approach of using green spaces to make people more mentally secure and physically healthy, stating that cities should include 'a physical and built environment that encourages, enables and supports health, recreation and well-being'.

One of the initial studies about the physiological profits of green spaces in 1978, showed that relaxation levels of volunteers increased when they viewed ‘vegetation-only’ and ‘vegetation with water’ colour slides. The basis of this conclusion, known as Stress Reduction Theory, was supported by data of the volunteers’ brain wave activity.

More recent studies argue that the positive influence of green spaces depends on psychological factors of individuals, including self-enabling aspects (e.g., motivation and attitude.) They may also depend on personal barriers (e.g., ill health and lack of time), and in particular, residential location.

A study assessed the effectiveness of blue-green spaces on the mental health of those affected by quarantines and lockdowns during the COVID-19 pandemic. It demonstrated that people with access to outdoor spaces (e.g., balcony and garden) coped better with social isolation and lifestyle changes.

The setting of an outdoor party. | Susanne Nilsson / Flickr

This study was based on the response of 5218 individuals from nine countries, including Spain, which was undergoing a ‘severe lockdown’ at the time. The authors found that residents in Spain experienced positive emotions (‘happy’ was mentioned in 30.1% of responses) if their views included natural elements. However, considering residents with limited or urban views, only 23.3% of individuals reported ‘happy’ emotions in lockdown.

‘The authors found that residents in Spain experienced positive emotions ('happy' was mentioned in 30.1% of responses) if their views included natural elements.’

This study showed that those with limited views or urban views have a greater chance of experiencing anxiety and depression. Unfortunately, a proportion of individuals who live in urban areas do not have access to private green spaces or balconies. Notably, the benefits of green spaces demonstrated in this study depend on the accessibility to these areas.

Green spaces have the potential to reduce racial health disparities

When considering the current COVID-19 pandemic, green spaces have also been recognised for their influence on racial health disparities. A nationwide study used data from 125 U.S counties (making up 40.3% of the U.S population) to show how five core mechanisms of green spaces essentially produce lower racial disparities in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection rates.

These five mechanisms state that an increase in the number of green spaces leads to (i) more people outdoors, (ii) more physical activity for various racial groups, (iii) boosted mental-well being, (iv) strengthened social skills and (v) improved air quality via reduced exposure to particulate matter (PM).

All together, these five mechanisms explain how differences in access, quality and quantity of green spaces in different counties can influence racial health disparities by 18%. This finding may help bridge the gap for those affected by racial health inequalities.

Increasing the number of green spaces accessible to communities can help bridge the gap for those affected by racial inequalities in health outcomes | Nerea Marti Sesarino / Unsplash

Green spaces can help reduce PMS symptoms

Another recent study showed that lifelong exposure to residential green spaces can have a positive effect on the symptoms of PMS. For many women, PMS can trigger anxiety, depression, and overall neuroticism. It is therefore critical to explore how negative factors associated with PMS can be mitigated.

A study used questionnaire responses from 1069 Scandinavian women aged 18-49 years, and satellite-derived Normalized Difference Vegetation Index (NDVI) data on green spaces. Responses were analyzed against a PMS symptom count, ranging from zero to eight.

The authors concluded that every interquartile range increase in NDVI resulted in a 6% decrease in the incidence rate of PMS symptom count. In other words, exposure to green spaces was associated with a lower probability of experiencing PMS symptoms. Specifically, a closer proximity to nature correlated to lower odds for 50% of the investigated PMS symptoms, including anxiety and depression.

‘Closer proximity to nature correlated to lower odds for 50% of the investigated PMS symptoms…’

The potential to reduce air pollution

Another health benefit of green spaces that has been discussed for almost a century is the potential to decrease air pollution levels via reductions of harmful levels of PM. Quantitative studies regarding the effect of green spaces on PM typically include models, real-life measurements or experiments. A novel literature review highlights the key advantages of the association between green spaces and PM.

Firstly, green spaces have a deposition effect on PM concentrations, through the potential to modify, delay or remove airborne PM. Deposition can be defined as a temporary or permanent settlement of PM on plants.

Deposition is viewed as a favourable event that prevents the resuspension of airborne PM into the atmosphere. A study demonstrated how the presence of roadside vegetation was correlated with a 60% reduction in PM via deposition effects.

‘The presence of roadside vegetation was correlated with a 60% reduction in PM via deposition effects.’

Secondly, vegetation is known to modify PM. For example, some plants can bioaccumulate individual PM elements (e.g., airborne metals) through selective sorption via the roots). Likewise, microbial communities present in soil can degrade pollutants and have detoxification effects.

A session for urban planning. | sub>urban Reinventing the Fridge / Flickr

Thirdly, green spaces can affect air quality via dispersion mechanisms, whereby plants act as physical barriers to pollutants, altering the course or speed of airborne PM. Of course, this effect depends on the location, alignment, height, depth and density of plants.

Reducing air pollution through green spaces also has positive benefits for bodily functions. New evidence showed green spaces can improve fetal renal functions by reducing levels of air pollution, as mentioned above. This novel study showed that residential green spaces within a 100 metre radius were associated with higher glomerular filtration rates (eGFR) in newborns, which is a sign of healthy body functionality.

Based on the growing body of literature explaining the importance and contribution of green spaces in urban areas, it seems obvious that effective urban planning should acknowledge the inclusion of parks and playing fields. Despite all of this research, it remains a challenge to translate scientific evidence into prospects for urban planning.

It is imperative to further explore and discuss the effects of green spaces on human health, as 69.6% of the global population is expected to reside in urban areas by the year 2050, according to a United Nations report published in 2004. In this future scenario, the documented advantages of green spaces on mental health become especially important to avoid potential community conflicts.

‘It is imperative to further explore and discuss the effects of green spaces on human health, as 69.6% of the global population is expected to reside in urban areas by the year 2050.’

Featured Image: Francisco Anzola | Flickr

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