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Green infrastructure and mental health

by Matt Downs

Dr Tom Young looks over some of the evidence that highlights the positive impact green infrastructure and systems have on mental health and the overall well-being of individuals.

The benefits of green space have been appreciated for millennia. The rise of dense urban spaces encouraged the development of green pockets within cities, to allow escape from hot, busy and noisy areas. 

Dr Tom Young is on the GRO Board and Environment Systems Manager at STRI Group.

Although the benefits of green spaces in cities have always been recognised, it is only in recent years that these benefits have begun to be fully quantified. This has started to allow policy and development strategies to place more emphasis on long-term human health outcomes of urban design. Much more work is needed to influence policy and planning legislation, but a wealth of knowledge and evidence proving the economic, human health and environmental benefits of incorporating green space into cities already exists.

Placed under the banner ‘green infrastructure’, urban green spaces range from parks, community gardens, green roofs, green walls, forests, landscaped areas and private gardens. Human health benefits are realised in a large number of interconnected ways, not all of which are immediately obvious. These can be broadly spilt into the following categories, Provisioning (natural resources produced), Regulating (maintaining the environment we live in) and Cultural (non-material benefits) (Coutts & Hahn 2015). I’ll focus on Regulating and Cultural benefits of green space.

Regulating 

Air pollution: vegetation can absorb and capture air pollution, reducing levels in the air for humans to ingest. However, care must be taken as sometimes certain species can contribute to respiratory disease though the production of pollen, volatile organic compounds or through altering air movement (Pawankar et al 2011, Hewitt et al 2020).

Climate regulation: Urban areas generally experience more extreme ranges in air temperature and flooding due to the large amount of hard, impermeable surfaces which absorb and reemit heat during the night, plus allow stormwater to run off extremely quickly. These effects are being exacerbated with the impact of climate change (Patz et al 2005). Elevated city temperatures are linked to 1000’s of deaths a year, particularly during heat waves. Large-scale modelling and studies have shown that city-wide greening can reduce overall city temperatures by up to 2.2ºC and the physiological equivalent temperature (method of assessing temperature effect on human body) by up to 14ºC (Balany et al 2020). Green spaces have also been used during heat waves as ‘cool’ islands to allow people to go and obtain some relief during hot night time conditions (Aram et al 2019).

Defours Place, London. Courtesy of GRO.

Cultural 

Mental health: A greater understanding of the link between human physical and mental health thankfully now places mental well-being as just as important as physical health (Coutts & Hahn 2015). Human relationships with nature is complex and hard to summarise concisely as individuals do respond differently to different environments depending on a range of social and physical health variables. However, the ability of green space to provide ‘mental restoration’ to renew “diminished functional resources and capabilities” results in a clear relationship with stress reduction and improved cognitive ability (Hartig & Staats 2003, Coutts & Hahn 2015, Ulrich et al 1991).

A classic study from Ulrich in 1984 showed that patients recovering from surgery required shorter hospital stays and reduced use of painkiller drugs when viewing trees from their hospital window, as opposed to a brick wall (Ulrich 1984). 

Access to or visibility of nature has also been shown to significantly improve patient and carer experience for palliative (end of life) patients. Even simple methods such as viewing a bird feeder, having an access ramp from a care room or, as mentioned earlier, being able to view trees from a window can have a large positive effect on patient stress, psychological well-being of patient and satisfaction of family/care givers on quality of care (Sagha et al 2018).

Social

Physical activity: A large amount of literature now exists which shows a relationship between access to green space and physical activity (Kaczynski & Henderson 2007), which can translate into reduction in obesity (Lachowycz & Jones 2011), although the relationship is complex and requires further investigation. Additional benefits can be realised in the social interactions from creating and managing green spaces, for example community gardens and assets.

The pool of available data quantifying the many interconnected and complex ways in which green infrastructure can improve human lives is now vast. The role of green infrastructure professionals is to now use this wealth of information to obtain clear and concise metrics to justify the use of green infrastructure and systems as vital parts of urban developments. Armed with this type of data, the argument against nature and resident friendly design becomes diminished, with the old way of doing things, in my view, much less sensible or attractive.

www.strigroup.com

References

Aram, F., Higueras García, E., Solgi, E., & Mansournia, S. Urban green space cooling effect in cities, Heliyon, 2019, Volume 5, Issue 4,

Balany, F.; Ng, A.W.; Muttil, N.; Muthukumaran, S.; Wong, M.S. Green Infrastructure as an Urban Heat Island Mitigation Strategy—A Review. Water 202012, 3577.

Coutts, C.; Hahn, M. Green Infrastructure, Ecosystem Services, and Human Health. Int. J. Environ. Res. Public Health 201512, 9768-9798

Hartig, T.; Staats, H. Guest editors’ introduction: Restorative environments. J. Environ. Psychol. 200323, 103–107

Hewitt, C.N., Ashworth, K. & MacKenzie, A.R. Using green infrastructure to improve urban air quality (GI4AQ). Ambio 49, 62–73 (2020)

Kaczynski, A.T.; Henderson, K.A. Environmental correlates of physical activity: A review of evidence about parks and recreation. Leis. Sci. 200729, 315–354.

Lachowycz, K.; Jones, A.P. Greenspace and obesity: A systematic review of the evidence. Obes. Rev. 201112, e183–e189.

Pawankar, R.; Canonica, G.W.; Holgate, S.T.; Lockey, R.F. WAO White Book on Allergy 2011–2012: Executive Summary; World Allergy Organization: Tokyo, Japan, 2011.

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