Going green in the city
The relationship between nature within urban settings on physical and mental health
Welcome to the latest Compassionate Nature article, which continues the consideration of greenspaces within urban settings and the relationship to health.
“We have a responsibility as human beings to take care of nature in our cities. In return, the benefits to our health would be huge.”
The words of Dr Cecil Konijnendijk, Professor of Urban Forestry at the University of British Colombia, quoted in a Natural History Museum (NHM) article by Callum Mair, highlights the dual benefit to both wildlife and public health from supporting nature within urban environments. In the last edition of Compassionate Nature the relationship of greenspaces such as public parks within town and cities was considered with a focus on the health of older people. The NHM article highlights other identified health benefits which greenspaces and vegetation support urban residents with, including mitigating air pollution, helping to manage extreme temperatures and benefits to mental wellbeing. Konijnendijk presents an argument that linking up green spaces and loosing control of nature within cities is required to help with maximising the support of the wildlife we share the spaces with, which also improves the health benefits we may experience.
The NHM article further highlights, as the studies included in the previous Compassionate Nature post did, that access to public green spaces is not equal for everyone, with the elderly, ethnic minority groups and those from socioeconomically deprived areas less likely to have access to green or blue spaces.
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In a 2023 paper Konijnendijk suggested a “3-30-300” guide for urban forestry planning to support wildlife, benefit public health and improve accessibility to greenspaces. Urban forestry is defined by Forest Research, part of the UK’s Forestry Commission, as “all the trees in the urban realm – in public and private spaces, along linear routes and waterways and in amenity areas. It contributes to green infrastructure and the wider urban ecosystem. It provides numerous benefits to human society and it does so in vast quantities.”
In the suggested guidance the 3 relates to the ability of a resident to see at least three trees from their home, school or workplace. The 30 relates to having at least 30% of tree canopy coverage within neighbourhoods of town and cities. To support accessibility and address inequalities it is important to note this is at neighbourhood level rather than town or city level and where there are limitations on growing trees the target should be at least 30% vegetation. Lastly the 300 relates to the World Health Organisation guidance that every resident should have a free public greenspace within 300 meters of their home. The 30 and the 300 have evidence supporting them while Konijnendijk choose 3 for the visible trees to link it in with the other two numbers.
A recent paper by Jonathon Taylor and colleagues (2024) underlines the physical health benefits from urban forestry with regard to extreme heat. Their analysis suggests that tree coverage within the city of London resulted in 153 less deaths as a result of hot temperatures across the period 2015 to 2022 . The analysis used data from the Met Office, tree canopy coverage and population statistics, finding that areas with greater tree coverage during the 2022 heatwaves had significantly lower average temperatures than areas with less coverage.
In addition to the physical health benefits, what further evidence do recently published papers offer around urban nature and mental health benefits ?
Greenspace characteristics
Are all types of urban greenspaces equal in terms of health benefits? What characteristics of those spaces may be more beneficial than others? Femke Beute and a team of international researchers 2023 scoping review tried to address these questions by exploring the evidence base for the influence on mental wellbeing and mental illness of different types of greenspaces and their characteristics.
Research geek aside - a scoping review helps to determine the scope of evidence towards a topic, alongside indicating the level and type of available research. It can be useful for considering emerging evidence and can help identify gaps and future directions for research.
In the review the authors suggest that greenspaces within urban settings offer three pathways supportive to public health. Firstly they can mitigate negative physical health factors, such as air pollution. Secondly they offer a restorative environment that can benefit cognitive and emotional states. Thirdly they support something they term instoration, covering activities which benefit wellbeing such as exercise and social interaction. The review included peer-reviewed quantitative studies of all age groups from 1995 to 2020 which considered greenspace and mental wellbeing, with the studies covering various designs (e.g. interventions, comparisons). This provided a sample size of 215 studies, with the selection process highlighting a huge increase in related studies from 2018 onwards.
The results of the review suggest that forests, parks and trees/vegetation were the most studied greenspaces. I found it interesting that gardens, which contribute a huge amount to urban greenspace coverage, were lower down in the type of space studied and that nearly half of the studies which included a garden were from Asia. The majority of the selected studies considered greenspaces within the context of healthy populations, with only 23 studies involving participants from clinical populations. Over a third of the studies (36%) used University students for the participants, a common occurrence within psychological studies. Most of the studies considered the influence from visiting greenspaces, with much less research around their use for exercise or as part of a healthcare programme.
Overall the review found there were not enough studies that had compared different types of greenspaces or their characteristics with regard to mental health benefits to draw any firm conclusions. Additionally the review highlights that often researchers are unclear in the description and definition of the greenspaces they are considering. While the majority of the studies included looking at exposure to greenspaces, what individuals experienced from doing so is under researched and would benefit from qualitative studies. The review itself has a limitation on how the researchers choose to categorise the selected 215 studies which may have influenced the review findings. The clear message the review presents is that the current evidence base on the characteristics of greenspace and mental wellbeing is mixed and unclear, with more well defined research required to understand what is beneficial especially for those experiencing specific mental health conditions.
Positive influences
A 2023 systematic review by Finnish researchers considered the influence of greenspaces upon individuals levels of subjective wellbeing and happiness. Manoj Syamili and colleagues reviewed studies published from 2013 to 2023 that involved participants aged 15 or older and which assessed subjective wellbeing benefits as a result of exposure to or an intervention involving an urban greenspace. The review process selected 57 studies, which were an almost even balance of global north and global south publications. The majority of the studies were surveys, with 8 field studies, and measured subjective wellbeing from cognitive and emotional perspectives, such as mood state or life satisfaction. Greenspaces were assessed around characteristics such as quality (e.g vegetation) and frequency of use. Significant positive relationships were found between subjective wellbeing and, in order of influence, greenspace accessibility, quality, exposure, frequency and proximity. However the review highlights that with multiple measures of subjective wellbeing employed across the studies it is hard to combine the study results and assess overall benefits. The review also highlights that social factors were found to be influential on the benefits associated to mental wellbeing from greenspaces, noting that levels of crime and social cohesion meditated the relationship. So while it again supports the evidence towards certain characteristics being helpful, assessing how and why these may benefit mental wellbeing is difficult from the existing evidence base.
Long term view
One issue that reviews of evidence and studies often mention is the lack of longitudinal research. However, in 2023 a large scale longitudinal study was published which provides some further insight into the relationship between proximity and accessibility of green and blue spaces to mental wellbeing. Rebecca Geary and a research team undertook a population study of adults aged 16 years old and over living in Wales, using anonymised data from the National Health Service, demographic data and environmental data. The project was sponsored by the National Instutite for Health and Care Research, which is funded by the Department of Health and Social Care, and included the data of just over 2.34 million Welsh adults across the time period of 2008 to 2019. The study considered the proximity of publicly accessible natural spaces to levels of common mental illnesses, such as depression, alongside considering demographic and socioeconomic factors. The individuals within the study consisted of 51% males and 49% females, with just under a quarter (22%) having a diagnosed common mental illness during that time, which were more prevalent within females.
The analysis suggested that both more vegetated greenspaces and greater accessibility to greenspaces corresponded with lower levels of mental illness. The benefits to mental health from greenspaces appeared to be greater to those individuals living in deprived areas. The analysis also suggested that greenspace proximity may offer a preventative factor to individuals who had a historical mental illness. There are limitations to the analysis, including that the NHS data did not provide the opportunity to differentiate between mental illnesses or their severity. Additionally the identification of a mental illness was only based on where medication had been prescribed, so not all cases were available to the analysis. Despite these limitations, this study provides a longer term view on the positive influence of nature within urban settings upon individuals mental health.
In his recent book Urban Jungle Ben Wilson highlights that John Claudius Loudon, the landscape designer of Derby Arboretum who featured in the previous post on parks, had in the 19th century stated that residents of towns and cities should have access to greenspaces within half a mile of their homes. This is not that dissimilar to the current WHO guidelines. The relationship of nature and health within our towns and cities is not something new, however rapid increasing urbanisation during the 20th and 21st centuries coupled with the adverse effects to the climate of human activities, has brought a pressing need to encourage both greater contact and connection with nature.
In his book, Wilson argues that the term urban nature is incorrect and it should be urbane nature, to reflect the way that we have controlled nature in places such as parks. This control is something the Victorian designers like Loudon would have recognised and encouraged but perhaps that this is the difference from their approach to one that is needed now. Wilson highlights that some of the most biodiverse urban spaces are private gardens, which account for large percentages of urban land. For those town and city residents with a garden, the greenspace which can do so much to support wildlife and our health is literally on the doorstep.
To support nature in our urban settings perhaps we need to loosen control, to allow the greenspaces, whether a public space such as a park or a private space like a garden, to be more “wild” and help to address the decreasing levels of wildlife. In doing so perhaps we may find a healthier relationship with both nature and our own wellbeing.
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References
Beute, F., Marselle, M. R., Olszewska‐Guizzo, A., Andreucci, M. B., Lammel, A., Davies, Z. G., ... & de Vries, S. (2023). How do different types and characteristics of green space impact mental health? A scoping review. People and Nature, 5(6), 1839-1876. https://doi.org/10.1002/pan3.10529
Geary, R. S., Thompson, D., Mizen, A., Akbari, A., Garrett, J. K., Rowney, F. M., ... & Rodgers, S. E. (2023). Ambient greenness, access to local green spaces, and subsequent mental health: a 10-year longitudinal dynamic panel study of 2· 3 million adults in Wales. The Lancet Planetary Health, 7(10), e809-e818. https://doi.org/10.1016/S2542-5196(23)00212-7
Konijnendijk, C. C. (2023). Evidence-based guidelines for greener, healthier, more resilient neighbourhoods: Introducing the 3–30–300 rule. Journal of forestry research, 34(3), 821-830. https://doi.org/10.1007/s11676-022-01523-z
Syamili, M. S., Takala, T., Korrensalo, A., & Tuittila, E. S. (2023). Happiness in urban green spaces: A systematic literature review. Urban Forestry & Urban Greening, 128042. https://doi.org/10.1016/j.ufug.2023.128042
Taylor, J., Simpson, C., Brousse, O., Viitanen, A. K., & Heaviside, C. (2024). The potential of urban trees to reduce heat-related mortality in London. Environmental Research Letters. https://doi.org/10.1088/1748-9326/ad3a7e
enjoyed reading this :)