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Greenery, Health, and Well-being: Understanding the health benefits of greenery at a city, neighbourhood,… Poskitt, Mark 2020-07

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Greenery, Health, &Well-beingUnderstanding the health benefits of greenery at a city, neighbourhood, and building scaleBy Mark Poskitt July 2020PLAN 528 Graduating ProjectIntroductionFor as long as I can remember, greenery has been an important part of many of the things I enjoy doing and that contribute to my personal well-being. Growing up in a semi-rural part of New Zealand, I spent a significant part of my youth and teenage years outside exploring local forests on foot or two wheels. Some of my best memories from this time are of multiday hikes in stunning, rugged natural settings, or of epic evening mountain bike rides with friends through steep, rooty, heavily jungled native bush. As I got older and began my academic career in geography, philosophy, and ultimately planning, I became increasingly intrigued about greenery and its intersection with well-being. Why did I find being under canopy so calming and restorative? Did other people feel this way too? Can greenery play a role in promoting well-being in the increasingly urbanized world many of us live in?Throughout my graduate studies I have been involved with a number of research projects relating to this topic, providing me with an opportunity to fully immerse myself in the literature around greenery and public health. This booklet provides an accessible synthesis and overview of some of the key relationships between greenery and health, how they work, and why they are important. Front page: Clark Park in East Vancouver. Photo by authorInset: The author enjoying some greenery on two wheels in Queenstown, New Zealand1Despite the growing abundance of research surrounding this topic and its crucial importance for the planning of healthy cities and neighbourhoods, I have found that many of my friends and colleagues (including those both inside and outside of the planning profession) know surprisingly little about this subject. As such, this booklet is not intended to be a highly academic paper or literature review. Rather, my aim is to create a succinct easy-to-use resource for planning practitioners, politicians, students, and the general public who wish to gain a better understanding of how greenery can benefit their individual health and the health of their communities. The main content of this booklet is structured into three distinct chapters related to scale: the city scale; the neighbourhood scale; and the building scale. At each scale, the effect of specific green design features (such as parks, street trees, or rooftop gardens for instance) on a particular component of human health is explained, alongside a brief discussion of the co-benefits of these design features. Each of these sub-sections contains a small set of carefully selected “recommended readings” for the curious reader wanting to delve deeper into a particular issue. Towards the end of the book, a  final chapter highlights the relevance of three other natural elements – sun, water, and air – for indirectly enabling the health benefits associated with greenery and for directly contributing to human health in their own right. Who is this booklet for?Navigation2Note: This document is best viewed in “two-page” mode, as facing pages tend to complement each other.Table of ContentsPart 1 | City + Regional ScalePart 2 | Street + Neighbourhood ScalePart 3 | Building ScalePart 4 | Sun, Water, AirGreenspacesGreenwaysUrban Forests   5  7  9  13  15  17   21  23 25   4   12   20  28Street Trees Green StreetsEffective Pervious Area (EPA)Green OutlooksGreen RoofsInterior Vegetation3City & Regional ScaleHealth Benefit:Pathway:Explanation:Greenspaces such as regional and city parks are associated with many health benefits. One of the most important yet commonly overlooked benefits is the positive effect these spaces can have on psychosocial well-being. Psychosocial well-being refers the subjective mental, emotional, and spiritual sense of well-being that individuals may experience as a consequence of positive social relations and interactions with others 1. When Greek philosopher Aristotle famously remarked that “man is by nature a social animal” he highlighted an important truth about our species. For thousands of years, humans have recognized the fundamental importance of social connection and community in contributing to well-being. Humans generally like creating and nurturing friendships, and positive interactions with other people is something we value and which makes us feel good 2. With modern advancements in the fields of public health, environmental studies, and human psychology, we are beginning to get a more robust understanding of the types of spaces that are conducive to psychosocial well-being, and why.  Greenspaces can offer unique and attractive recreational amenity areas that can serve as a formal and informal community meeting point3. For example, parks provide a space for team sports where members of a community can socialize and exercise simultaneously. Dogwalkers with nothing in common apart from their pets have the opportunity to exchange a friendly word with each other as they admire one-Social Interaction Psychosocial well-beingGreenspaces5The recreational pull of greenspaces means that many different people are using these public spaces concurrently, increasingly the likelihood of chance or intended social interactions. Photo of a city park in London (UK) by Timothy Mbugua.Part 1City + Regional ScaleCo-benefit:1 Burns R.A. (2017) Psychosocial Well-Being. In: Pachana N.A. (eds) Encyclopedia of Geropsychology. Springer, Singapore2 Kawachi, I., & Berkman, L. F. (2001). Social ties and mental health. Journal of Urban health, 78(3), 458-467.3 Kuo, F. E., Sullivan, W. C., Coley, R. L., & Brunson, L. (1998). Fertile ground for community: Inner-city neighborhood common spaces. American Journal of Community Psychology, 26(6), 823-851. doi:10.1023/A:10222940289034 Sugiyama , T., Leslie, E., Giles-Corti, B., & Owen, N. (2008). Associations of neighbourhood greenness with physical and mental health: do walking, social coherence and local social interaction explain the relationships?. Journal of Epidemiology & Community Health, 62(5), e9-e9.5 Kong, L., Lau, K. K. L., Yuan, C., Chen, Y., Xu, Y., Ren, C., & Ng, E. (2017). Regulation of outdoor thermal comfort by trees in Hong Kong.Sustainable Cities and Society, 31, 12-25.Recommended readings:Thermal regulationanother’s canine companion. For older adults, greenspaces offer a pleasant environment to meet with friends or observe the world from a park bench. For children, greenspaces can be an exciting and exploratory area to play in and make friends with other kids from the same neighbourhood. The recreational pull of greenspaces mean that all of these different people are using the same public space, which increases the likelihood of chance or intended social interactions. These interactions strengthen social bonds within a neighbourhood, and boost the subjective psychological feeling of well-being experienced by individuals that make up a community 4. Greenspaces can regulate the thermal environment in two key ways. Firstly, through the process of evapotranspiration, trees and vegetation in greenspaces emit absorbed solar energy in the form of moisture rather than latent heat 5. This cools the near-ground atmosphere. Secondly, tree canopy provides shade in summer months, which blocks the direct sun from hitting the ground. Both of these pathways have a cooling effect on the ground-level thermal environment that can improve the comfort of human users during summer months or in warm climates, and mitigate the potential for overheating, sunburn, and heatstroke.6Part 1City + Regional ScalePathway:Explanation:Greenways can be understood as “protected corridors of land managed for resource conservation and/or recreational use” 1. Greenways can be designated pre-emptively prior to any development in an area, or they can be ‘reclaimed’, as in the case of urban strips of land that have been transformed into green active transportation corridors. In many cities old railway lines are used for this purpose, such as the Arbutus Corridor in Vancouver. Greenways are often used to connect neighbourhoods with a downtown core, and integrate environmentally friendly forms of human mobility such as cycling and walking into the wider transportation network 1. At a metropolitan or regional scale, greenways can also be used to connect different municipalities.Given that greenways are primarily used to encourage active forms of human movement, the main health benefits associated with this design feature stem from the increased physical activity that these promote 2. Studies such as that on the Comox corridor in Vancouver (see case study) have shown that living close to a greenway increases the amount of physical activity an individual will do, whilst also reducing the amount of time they spend sedentary in cars 3. Both of these outcomes have significant physical health benefits. For example, increased physical activity contributes to lower rates of cardiovascular disease and obesity. Physical activity can also reduce the risk of type 2 diabetes and some types of cancers, lower blood pressure levels, improve sleep (which itself has a plethora of positive health benefits), increase bone and muscle strength, and enhances balance – an especially important physical health benefit for older people at risk of falls 4.Increased physical activityPhysical healthGreenwaysHealth Benefit:The Green Path (Den Gronne Sti) in Central Coopenhagen. Source: Jennifer Len Hart.7Co-benefit:1 Benedict, M. A., & McMahon, E. T. (2012). Green infrastructure: linking landscapes and communities. Island press.2 Dallat, M. A. T., Soerjomataram, I., Hunter, R. F., Tully, M. A., Cairns, K. J., & Kee, F. (2014). Urban greenways have the potential to increase physical activity levels cost-effectively. The European Journal of Public Health, 24(2), 190-195.3 Frank, L.D., Hong, A., Ngo, V.D.(2019). Causal evaluation of urban greenway retrofit: A longitudinal study on physical activity and sedentary behavior. Preventive Medicine. Volume 123, June 2019, Pages 109-116.4 Warburton, D. E., Nicol, C. W., & Bredin, S. S. (2006). Health benefits of physical activity: the evidence. Cmaj, 174(6), 801-809.5 NCDOT. (2013). WalkBikeNC: North Carolina Statewide Pedestrian and Bicycle Plan. Retrieved from readings:Economic activityAs well as encouraging physical activity and facilitating a shift away from car-centric transportation networks, greenways can provide many local economic benefits such as improving land values and generating tourism. In Oakland, CA, the three-mile green belt circulating Lake Merrit near the city centre is estimated to have added US$41 million to surrounding property values, whilst in Salem, OR, land directly bordering a greenway was found to be worth on average $1,200 more per acre than land only 1000 feet further away 1. Additionally, greenways can boost tourism and create economic opportunities for the likes of local bicycle shops, tour companies, restaurants and bars, retailers, and accommodation providers. In their state-wide pedestrian and bicycle plan ‘WalkBikeNC’ adopted in 2013 for example, the North Carolina Department of Transportation estimates that the construction of a further 300 miles of new greenway infrastructure would result in an annual increase of visitor spending of US$68 million, support 1,600 jobs, and generate $174 million for the state economy 5. Greenways are not only good for community health: they are good for business too.  Case Study | Comox-Helmken GreenwayPart of the Comox-Helmken Greenway. Source: Ken Ohrn via Spacing Vancouver.Greenways, such as the Arkansas Razorback Regional Greenway shown above, can attract tourists and stimulate local economic activity in addition to benefiting community health. The Comox-Helmcken Greenway (often referred to as the “Comox corridor”) constructed during 2013-2014 is an east-west green pedestrian and cyclist passageway connecting Vancouver’s West End neighbourhood (including the adjacent popular Stanley Park) to the rest of Vancouver’s downtown. From 2012-2015, a study by the UBC Health and Community Design Lab was undertaken to assess the travel, health and activity patterns of residents living nearby this greenway before and after the completion of the Comox corridor 3. Below are some of its key findings which highlight the associations between greenways, increased physical activity, and well-being for residents living near the Comox corridor during the study period:• Number of daily bicycle trips increased by 32.3%• The number of daily automobile trips decreased by 22.9% • 16% increase in the number of days participants engaged in moderate physical activity• 8% self-reported decrease in time spent sitting and being sedentary• 9.8% decrease in the number of days of poor physical and mental healthHealth Benefit:Pathway:Explanation:As with greenspaces and parks, urban forests provide a unique vegetated area designated for human recreation and ecological protection. Whereas trees are an important but non-essential component of these other two green design features, urban forests are heavily treed by definition, and dedicated human pathways may be a limited to small sections of the urban forest. Because of this, urban forests can often harbour a great variety of fauna and flora species, and act as a pocket of “wild” within the city. Unlike parks, urban forests are typically not extensively manicured or maintained. Urban forests have many human health benefits, both indirectly and directly 1. One particularly well documented benefit is the calming, stress-reducing effect forests can have on humans. Studies by Park et al 2 and Lee et al 3 and have showed that exposure to a forest environment for even a short amount of time can reduce stress levels – a result that is typically quantified by assessing salivary cortisol levels, one of the main biomarkers of physiological stress. Although there is a multiplicity of research documenting the link between exposure to trees and stress reduction, less attention has been given as to why this link exists. One explanation is that when early humans evolved, green forests were our home environments, associated with peace and safety. At a subconscious level, exposure to such environments enhances parasympathetic nervous system functioning – the part of the human body associated with “resting and digesting” that combats our internal “fight or flight” reaction associated with sympathetic nervous activity and high stress levels 4. Another interrelated hypothesis is that exposure to trees may help restore our attention (see Attention Restoration Theory) by reducing the amount of external stimulation and distractions we are surrounded by, and presenting us with a visually interesting and attractive natural environment that engages our fascination, giving our brain a chance to recoup 5. This in turn can enhance our ability to regulate and deal with stress, and induce a sense of relaxation and mental calmness. Enhanced immune functioning + Attention restorationStress reductionUrban ForestsUrban forests can have a calming, restorative effect on humans which can enhance immune functioning. Photo of Riccarton Bush, Christchurch (NZ), by Jason and Jamie Young.Part 1City + Regional Scale9Co-benefit:1 TreeCanada. (n.d.). Compendium of Best Urban Forest Management Practices. Chapter 3: Benefits of Urban Forests. Retrieved from Park, B. J., Tsunetsugu, Y., Kasetani, T., Hirano, H., Kagawa, T., Sato, M., & Miyazaki, Y. (2007). Physiological effects of shinrin-yoku (taking in the atmosphere of the forest)—using salivary cortisol and cerebral activity as indicators—. Journal of physiological anthropology, 26(2), 123-128.3 Lee, J., Park, B. J., Tsunetsugu, Y., Ohira, T., Kagawa, T., & Miyazaki, Y. (2011). Effect of forest bathing on physiological and psychological responses in young Japanese male subjects. Public health, 125(2), 93-100.4 Kuo, M. (2015). How might contact with nature promote human health? Promising mechanisms and a possible central pathway. Frontiers in psychology, 6, 1093.5 Kaplan, S. (1995). The restorative benefits of nature: Toward an integrative framework. Journal of environmental psychology, 15(3), 169-182.6 Nowak, D. J., Greenfield, E. J., Hoehn, R. E., & Lapoint, E. (2013). Carbon storage and sequestration by trees in urban and community areas of the United States. Environmental pollution, 178, 229-236.Recommended readings:Carbon sequestration Carbon sequestration refers to the process of capturing and storing atmospheric carbon dioxide. Carbon dioxide is the most commonly produced GHG emission and is one of the key drivers behind anthropogenic accelerated climate change – a global phenomenon that has, and will continue to have, many significant implications for the health of human and non-human life. Because of their ability to store and process carbon and produce oxygen, trees are nature’s own sequestration specialist. The average annual carbon storage rate per square meter of tree cover in urban areas is estimated to be 0.28kgC/sq.m, and the size of a tree directly influences its carbon storage and sequestration potential. Large trees greater than 77cm in diameter sequester approximately 90 times more carbon than small trees less than 8cm in diameter 6. The carbon uptake of a tree is also related to its leaf longevity, meaning that evergreen trees contribute greater to carbon reduction than comparable sized deciduous trees. Succinctly, urban forests – especially those containing large, mature, evergreen trees – can play an important role in sequestrating carbon and mitigating the impact of human pollution on the health of our planet.Case Study | Attention Restoration TheoryAttention Restoration Theory (ART) is an important idea within the greenery and health literature, first put forth by researchers Rachel and Stephen Kaplan in the late 1980s. According to this theory, exposure to nature has the ability to renew and restore attention after exerting mental energy. The Kaplans suggest that this process involves four key cogitative phases:1) A clearer head and ability to concentrate 2) Mental fatigue recovery3) Soft fascination or intrigue4) Reflection and restorationEach of these phases are important contributors to the overall ART process, and do not necessarily have to occur in the sequential order outlined above. For an environment to be restorative and conducive to allowing these cognitive phases to occur however, it must “be away” or separate from a location where a person has been exerting mental energy (usually in a physical sense); allow for ‘soft’ or ambient fascination (such as low stimulation environments that are interesting or appealing but do not demand out full attention or concentration); be immersive and comfortable; and be compatible with a person’s personal preferences – meaning they must choose to be in said environment for their own reasons and guided by their own motivation, rather than for external reasons. Although a seemingly abstract hypothesis in this light, many studies over the last several decades have supported and illustrated the applicability of this theory to different types in restorative environments – including natural, vegetated settings. 10Street & Neighbourhood ScalePathway:potential to indirectly benefit human health and well-being. In addition to these however, research has demonstrated that exposure to nearby street trees and greenery can have a calming effect on humans, which can enhance their ability to regulate emotions and aggression, ultimately reducing incidents of crime. For example, a 2001 study of 145 residents of inner-city public housing in Chicago by Kuo and Sullivan1 found that “residents living in relatively barren buildings reported more aggression and violence than did their counterparts in greener buildings” with exposure to nearby nature (grass, street trees, and vegetation). Controlling for all other factors and likely confounding variables, the authors of this study also found that “levels of mental fatigue were higher in barren buildings, and aggression accompanied mental fatigue” (pg.543). Succinctly, those exposed to greenery had better attention functioning and less mental fatigue than residents of barren buildings, which positively impacted their ability to regulate emotions and control aggressive tendencies. At a community scale, this decreased the incidents of domestic violence amongst public housing residents 1. Interestingly, this study is not alone in reporting the linkages between greenery and crime reduction. A growing body of evidence suggests that ‘greening’ vacant lots or public spaces (by putting in community gardens and trees) Explanation:Key primary functions of street trees are to contribute to the character and aesthetic of a neighbourhood, create a pleasant walking environment for pedestrians, reduce the amount of direct sun exposure of store frontages and the sidewalk, and in some instances, act as a traffic calming measure. All of these functions have the can reduce nearby crime in an area 2. A study of the effect of greening vacant lots on crime in Youngstown, OH, during 2016 for example, showed a statistically significant reduction in all nearby crime types measured (including felony assault, burglary, theft, car theft, and robbery) in those lots that had received a green treatment versus those that had not 3. Similarly, a more recent study in Portland by Donovan and Prestemon (2012) found that large mature trees in public right of ways are generally associated with lower rates of criminal activity in surrounding areas 4. The authors suggest that this relationship may be partially explained by the fact that trees make public spaces more desirable which enhances pedestrian activity and increases the chances of a criminal being observed. Trees also indicate to potential criminals that a neighbourhood is well cared for, suggesting that were they to attempt a crime, they may be more likely to be observed by an authority. Both of these pathways – actual increased neighbourhood activity and the perception of activity / authority – can disincentivise criminal activity. Such potential explanations are supported by the likes of Kuo and Sullivan 1, who suggest that well maintained trees and vegetation outside a house act as a cue to potential criminals “that the inhabitants actively care about their home territory and potentially implying that an intruder would be noticed and confronted” (pg.347).  1) Reduced mental fatigue + enhanced attention and ability to regulate emotions2) Increased community presence + perception of passive surveillanceReduced aggression + crime reductionStreet TreesHealth Benefit:Part 2Street + Neighbourhood Scale13Co-benefit:1 Kuo, F. E., & Sullivan, W. C. (2001). Aggression and violence in the inner city: Effects of environment via mental fatigue. Environment and behavior, 33(4), 543-571.2 Spector, J. (2016, April). Another reason to love urban green space: it fights crime. Retrieved from Kondo, M., Hohl, B., Han, S., & Branas, C. (2016). Effects of greening and community reuse of vacant lots on crime. Urban Studies, 53(15), 3279-3295.4 Donovan, G. H., & Prestemon, J. P. (2012). The effect of trees on crime in Portland, Oregon. Environment and behavior, 44(1), 3-30.5 Clay, E. (2002). Food security: concepts and measurements. In Thomas, H.C. (Ed.) Trade Reforms and Food Security. Rome, Lazio: Publishing Management Service of the United Nations. Retrieved from readings:Food securityA growing trend in many cities around the world is the mapping of edible street trees, such as those which produce fruits and nuts. “Falling Fruit” for example, is a global cartographic database which displays millions of records of edible trees from different cities around the world, including their precise geographic location and species type. Databases of this sort can enhance community access to a plethora of nutritious tree-borne edibles, thereby contributing to local food security – the condition where “all people, at all times, have physical, social and economic access to sufficient, safe and nutritious food which meets their dietary needs and food preferences for an active and healthy life” 5. An illustration of this in practice is the Trees to Tables program led by the Ottawa Food Bank (ON), which aims to fight hunger in Ottawa by harvesting fruit from city-owned street trees and distributing it amongst local food banks. The grassroots Edible Landscape Project in Ireland, which is currently coordinating the planting of community orchards and fruit and nut trees across Ireland, provides a further example of this co-benefit.14Studies such as that conducted by Kuo and Sullivan (2001) have shown that street trees proximal to (and visible from) residential buildings can have a calming and restorative effect on residents that can contribute to lower rates of aggression. Photo of street trees in a Chicago neighbourhood sourced from Sara Freund.Pathway:Co-benefit:neighbourhoods.A key benefit of green streets is the mitigation effect these can have on neighbourhood air and noise pollution 2. There are two pathways through which this can occur. The first is by providing a physical screen against pollution. In this instance, vegetation literally blocks, absorbs, or muffles sound produced by automobiles and traps the air pollution generated by these vehicles. The second, is through traffic calming. Often, green street initiatives will narrow the existing road width in order to provide more space for vegetation along a street verge. This in turn reduces the amount of traffic volume able to move along a street at any given time, which subsequently reduces the amount of air or noise pollution being generated. The diversity of vegetation within a streetscape can also create a more crowded visual field for drivers, which can subconsciously cause them to slow down and drive more cautiously. This may reduce vehicle noise, as well as contributing to a safer street. The positive health implications of green streets should not be understated 3. According to the WHO, air and noise pollution are the two leading environmental threats to public health globally. Recent estimates from this organization suggest that at least 1 million healthy life years are lost in western Europe alone annually as a consequence of traffic induced noise pollution 4, and 4.2 million annual premature deaths caused worldwide as a Explanation:A ‘green street’ is a road or street that incorporates green infrastructure features (both natural and man-made), including trees, vegetation, green walls, small gardens, grass, swales, and low impact development features that facilitate improved hydrological or ecological functioning 1. Green streets can include street trees but are much more than just that and have become an urban movement in their own right. Many north American cities, including Philadelphia, Milwaukee, Toronto, Vancouver, and New York, have dedicated ‘green streets’ programmes which aim to highlight the benefits of these street typologies and often provide funding and guidance for community groups wanting to create green streets within their own consequence of ambient (outdoor) air pollution 5. Although green streets exist at a neighbourhood level, the impact they can have on population health when implemented across entire cities is considerable. Green streets are one of the easiest street-retrofit strategies that can be used to simultaneously enhance the quality of a streetscape environment for pedestrians, disincentivize automobile usage, and improve safety and public health 1. Physical screening of pollution + traffic calmingBiodiversity corridors Reduced air + noise pollution exposureGreen StreetsHealth Benefit:Part 2Street + Neighbourhood ScaleIn addition to mitigating the effects of pollution on pedestrians and residents, green streets can act as a wildlife corridor by providing a contiguous strip of greenery. This is especially applicable if a network of continuous green streets connects two separate large ecological patches such as an urban forest or large urban park, enabling an easier passage for animals from one habitat to the other.  Given that habitat fragmentation and destruction are indubitably one of the greatest risks to biodiversity in this day and age, preserving natural areas and increasing the connectivity between these within  our cities is crucial for the well-being of the non-human animals who share our cities and regions 6. 151 EPA. (2009). Green Streets: A Conceptual Guide to Effective Green Streets Design Solutions. Retrieved from GreenBlue Urban. (2015, April). Trees as Sound Barriers. Retrieved from Ulmer, J. M., Wolf, K. L., Backman, D. R., Tretheway, R. L., Blain, C. J., O’Neil-Dunne, J. P., & Frank, L. D. (2016). Multiple health benefits of urban tree canopy: The mounting evidence for a green prescription. Health & Place, 42, 54-62.4 WHO. (2011). Burden of disease from environmental noise: Quantification of healthy life years lost in Europe. Retrieved from WHO. (2018). Ambient (outdoor) air pollution fact sheet. Retrieved from Henry, R. C., Palmer, S. C., Watts, K., Mitchell, R. J., Atkinson, N., & Travis, J. M. (2017). Tree loss impacts on ecological connectivity: Developing models for assessment. Ecological Informatics, 42, 90-99.Recommended readings:Biodiversity corridors Green streets have many benefits, including their ability to mitigate flood risk, facilitate biodiversity, and screen nearby residents from harmful air and noise pollution detrimental to human well-being. Photo by jaminwell. Case Study | Noise + Human HealthWhen most of us think of global health crises,  it is unlikely that noise pollution will be  the first thing to come to mind. According to a growing body of research however, it is apparent that noise can, and is, detrimentally effecting human health globally in a number of significant ways. One of the most widespread impacts of noise pollution is noise-induced hearing loss. Other common negative effects include stress, high blood pressure, sleep disturbance, a reduction in productivity, and a general diminishing quality of life.A recent study undertaken by the WHO (2011) estimates that in terms of annual DALYs (disability adjusted life years) lost in Europe alone due to the health effects of noise pollution, 61,000 years are lost due to heart disease, 45,000 years for cognitive impairment of children, 903,000 years for sleep disturbance, 22,000 years for tinnitus, and 587,000 for annoyance 4. Noise pollution can stem from many causes, but the most common cause globally is road traffic.Photo by the author.16Pathway:the world as a superior flood mitigation strategy over expensive and cumbersome infrastructural solutions that must constantly be maintained 2.Explanation:A commonly overlooked health benefit of greenery in urban areas is its ability to enhance resilience against natural hazards that threaten human lives and livelihoods, such as floods 1. All greenery must, in order to survive, exist in soil so that it can absorb water and nutrients. In contrast to impervious surfaces such as concrete or asphalt, vegetated soils are porous and can infiltrate and store significant amounts of water in the occurrence of a heavy rainfall event. This reduces surface runoff, and eases the pressure placed on a city’s man-made drainage systems, thereby improving flood resiliency at a neighbourhood and street scale. Because of its effectiveness in enhancing drainage, greenery and green areas are increasingly being used by cities around So how does improved flood resilience benefit human health? Globally, floods are the most common natural disaster in both the developed and developing world and have the highest Increased natural infiltration + drainageEnhanced flood resilienceEffective Pervious AreaHealth Benefit:Increasing the effective pervious area of a neighbourhood can be achieved by implementing different forms of green infrastrucucture, and reducing the amount of exposed concrete or asphalt. What is ultimately comes down to however, is more vegetation in public spaces and streets. Photo by the author, East Vancouver, BC.17Co-benefit:EducationPart 2Street + Neighbourhood ScaleGreen infrastructure features and ecosystem services in urban environments that increase the effective pervious area of a streetscape provide a proximal educational resource for students at all levels in a wide-range of disciplines,  including ecology, hydrology, engineering, urban planning, urban design, public health, hazard resilience, and environmental studies. Students are able to analyse and assess first-hand the effectiveness of green design features and apply some of their theoretical knowledge from the classroom into practice. Alongside benefiting students’ learning, this may also provide an opportunity for productive research partnerships between universities, schools, municipal governments, and community groups that can ultimately improve and refine the success of targeted green interventions. amount of fatalities of any natural disaster type. In addition to the risk they pose to human life, floods have a huge impact on human livelihood and economies, which in turn can have numerous flow-on effects for human health. During 2019 in the USA alone, flood events in the Arkansas, Missouri and Mississippi river basins cost the national economy over US$20 Billion 3. At an individual health level, homelessness, lost employment, and disrupted social networks as a consequent of flooding can result in significant physical and emotional stress that is likely to impact all aspects of a person’s well-being. To illustrate the scale of these individual social health costs, a recent report compiled by Deloitte Access Economics 4 estimated that the 2010-11 Queensland floods in Australia caused approximately AUS $14.1 billion in damage, $7.4 billion of which can be attributing to “intangible” damages including psychological distress and ongoing mental health issues caused by these floods, an increase in risky substance use, short term unemployment, and an increase in family violence. According to one study by Alderman et al (2013), residents in Brisbane (capital of the state of Queensland, Australia) that were directly affected by these floods were 5.3 times more likely to report poorer health than those not impacted by the floods, 2.3 times more likely to have post-traumatic stress disorder (PTSD), 2.3 times more likely to report decreased sleep quality, and 1.9 times more likely to report psychological distress 5 . Due to increased sea levels and extreme weather events associated with climate change, flood risk is likely to increase in many areas around the world over the coming decades. Now more than ever, there is a need for innovative and efficient strategies to mitigate the impact of flooding in cities. Utilizing green ecosystem services provides a promising, cost-effective direction with many attractive co-benefits. 1 EEA. (2017, November). Green Infrastructure and Flood Management: Promoting cost-efficient flood risk reduction via green infrastructure solutions. Publications Office of the of the European Union, Luxembourg. Retrieved from2 Opperman, J. (2014). A Flood of Benefits: Using green infrastructure to reduce flood risks. The Nature Conservancy. Retrieved from Smith, A. (2020). 2010-2019: A landmark decade of U.S. billion-dollar climate and weather disasters. Retrieved from Deloitte Access Economics. (2016, March). The economic cost of the social impact of natural disasters. Retrieved from Alderman, K., Turner, L. R., & Tong, S. (2013). Assessment of the health impacts of the 2011 summer floods in Brisbane. Disaster medicine and public health preparedness, 7(4), 380-386.Recommended readings:18Building ScalePathway:many times by different researchers in a diversity of settings, and cited by thousands. Results have been astonishingly consistent. In many modern hospitals, external windows are an increasingly advocated-for design feature 2. But how does this relationship work? What is it about a natural view that is so therapeutic? As with forests walks, relaxing in the park, or Explanation:In 1984, the American researcher Roger Ulrich published a paper reporting an unusual but profound finding about the therapeutic benefits of viewing nature in hospital patients recuperating from surgery 1. In the words of Ulrich himself: “Twenty-three surgical patients assigned to rooms with windows looking out on a natural scene had shorter postoperative hospital stays, received fewer negative evaluative comments in nurses’ notes, and took fewer potent analgesics than 23 matched patients in similar rooms with windows facing a brick building wall.”Since then, Uldrich’s study has been replicated Enhanced Immune FunctioningEnhanced healing + improved patient experienceGreen OutlooksHealth Benefit:Uldrich’s 1984 study showed that green outlooks can enhance post-surgery healing rates and improve the patient experience. Since then, an abundance of research highlighting the health and economic benefits of incorporating greenery into hospital design has transpired, contributing to a gradual rethink of the way our healthcare facilities are built.strolling along a greenway, visual exposure to nature from inside a building can arrest our attention, calm our brain, and reduce sympathetic nervous activity in the body. This in turn can reduce stress levels and blood pressure, enhance pain tolerance, and boost immune functioning 3. The end result: happier, more satisfied patients; shorter hospital stays; reduced healthcare spending, and better healthcare outcomes 4. 21Co-benefit:1 Ulrich, R. (1984). View through a window may influence recovery. Science, 224(4647), 224-225.2 Beatley, T. (2011). Biophilic cities: integrating nature into urban design and planning. Island Press.3 Yamaguchi, Y. (2015, October).Better Healing from Better Hospital Design. Retrieved from Kazmierczak, L. (2018, April). Nature’s Cure: How biophilic design can enhance healing. Retrieved from NHS. (2019). Guide to NHS waiting times in England. Retrieved from 6 Haddad, L. M., Annamaraju, P., & Toney-Butler, T. J. (2020). Nursing shortage. In StatPearls [Internet]. StatPearls Publishing.Recommended readings:Reduced healthcare spendingPart 3Building ScaleA direct and important co-benefit of natural views within hospital settings is reduced healthcare spending. In our society today, many hospitals around the world are sorely understaffed, under resourced and underfunded. This not only applies to hospitals in the developing world, but also many hospitals in the global North too. Waiting times for non-urgent consultant-led treatment in Britain’s National Health System (NHS) for example are commonly up to 18 weeks from the time an appointment is booked 5, whilst America is currently experiencing a significant nursing shortage that is projected in worsen as the baby boomer demographic group reaches old age 6.  In this context, any healthcare savings derived from exposure to greenery enable resources to be reallocated to other areas within the healthcare system where there is significant need.  22Pathway:to the UHI effect the annual mean temperature within a city with more than one million inhabitants can be between 1-3°C higher than surrounding rural areas, and on a clear calm night this number can reach upwards of 10°C 2.By raising the average temperature of a city, UHI’s are a health concern for individuals in a number of ways, although these negative effects are most keenly felt in summer months and/or in already hot climates. For example, UHI can increase urban temperatures to a level that is physically uncomfortable – and even dangerous – for pedestrians 3. Asides from putting them in a bad mood, this can potentially lead to more serious health outcomes such as dehydration, heatstroke, and even death. Urban heat islands have been demonstrated to amplify the frequency and severity of heat waves, and the number of mortalities during these events 4. With global temperatures set to increase over the coming decades as a consequence of climate change alongside a continued rural-urban drift, finding ways to address the UHI effect is crucial for protecting the well-being of urban residents – especially those most vulnerable to heat exhaustion, including seniors and young children. Vegetation has been demonstrated to be effective at mitigating the effects of an urban heat island through processes of evapotranspiration and by providing shade. Evapotranspiration refers to the Explanation:The urban heat island (UHI) effect refers to a microclimate situation where an urban environment is warmer than surrounding rural areas. The UHI effect is a widely recognized and discussed phenomenon within the literature, and is one of the most commonly cited examples of anthropogenic modification of the atmospheric environment 1. There are several overlapping reasons why a UHI might occur. The heat produced by human activities in cities, including transportation and the heating of buildings for human comfort, is a primary contributor. The material composition of cities from common construction materials including metal, concrete, and asphalt, which are prone to absorb solar energy and reemit it as sensible heat that warms the near ground atmosphere, is another. Due Increased evapotranspirationReduced urban heat island (UHI) effectGreen RoofsHealth Benefit: process whereby vegetation will emit absorbed solar energy in the form of moisture. In contrast to the sensible heat emitted by concrete for example which warms the near-ground atmosphere, the moisture produced by vegetation actually has the opposite effect of cooling the air, thereby directly mitigating the effects of UHI. In addition to this process, vegetation can also reduce the UHI effect by providing shade. This can make the public realm more comfortable for people and reduce the amount of direct solar energy directly hitting exposed urban surfaces in the first place. Given that a large proportion of urban space is occupied by buildings, one of the key areas where vegetation could be implemented as a UHI mitigation strategy is on roofs 5. In contrast to ground level where vegetation features and green spaces are more common, the roofs of large buildings in many cities around the world have conventionally been left as blank concrete slabs. Given that interspersing greenspace and vegetation into the built environment regularly will have a greater impact in reducing UHI than creating highly concentrated greenspace areas 6, green roofs have significant potential as a key strategy for reducing UHI in cities. 23Part 3Building ScaleCo-benefit:1 EPA. (2014, June). Reducing Urban Heat Islands: Compendium of Strategies. Retrieved from Oke, T. R. (2002). Boundary layer climates. Routledge.3 Santamouris, M. (2014). Cooling the cities–a review of reflective and green roof mitigation technologies to fight heat island and improve comfort in urban environments. Solar energy, 103, 682-703.4 Tan, J., Zheng, Y., Tang, X., Guo, C., Li, L., Song, G., ... & Chen, H.(2010). The urban heat island and its impact on heat waves and human health in Shanghai. International journal of biometeorology, 54(1), 75-84.5 Susca, T., Gaffin, S. R., & Dell’Osso, G. R. (2011). Positive effects of vegetation: Urban heat island and green roofs. Environmental pollution, 159(8-9), 2119-2126.6 Li, J., Song, C., Cao, L., Zhu, F., Meng, X., & Wu, J. (2011). Impacts of landscape structure on surface urban heat islands: A case study of Shanghai, China. Remote Sensing of Environment, 115(12), 3249-3263.7 Government of South Australia. (2010, December). Rain Gardens, Green Roofs and Infiltration Systems: Water Sensitive Urban Design (WSUD) Summary Sheet. Retrieved from readings:Water sensitive urban design (WSUD)A significant co-benefit of rooftop gardens is their ability to reduce runoff and trap contaminants during rainfall events, making them a prime example of water sensitive urban design 7. Conventionally, most urban buildings constructed within the last millennium have a bare, impervious roof from which rainfall is funneled directly and rapidly into a city’s stormwater drainage system.  Any pollutants or rubbish on these roofs are swept up by this runoff.  Because of the speed at which this process occurs, impervious rooftop surfaces will typically lead to an increased runoff volume and peak flows in a heavy rainfall event, which can place significant pressure on urban drainage systems and increase the risk of a flood event. Rooftop gardens can mitigate this risk by providing a pervious vegetated area that can infiltrate and store rainwater, thereby reducing the amount of water entering urban drainage systems and slowing down the rate at which this occurs. The soil underneath this vegetation can also trap pollutants contained within surface runoff, mitigating the amount of contaminants entering a stormwater system. Rooftop gardens, such as this one atop Chicago’s city hall, can reduce UHI whilst simultaneously reducing urban flood risk by infiltrating and slowing down surface runoff.Photo sourced from ShareAmerica.24Pathway:38% reduction in fatigue, and a 44% reduction in anger and hostility amongst workers compared to a control group (no plants introduced) who experienced no changes to these categories 1.The implications of these numbers should be apparent: workers who are less fatigued, stressed, and angry, will work more efficiently, improving the overall efficiency of a workplace environment. Such implications have been confirmed by recent research in the academic community, such as a 2014 paper from the Explanation:The therapeutic benefits of greenery and biophilic architecture are increasingly being utilized by some employers around the world as an ambient strategy to enhance employee productivity in the workplace environment. As described elsewhere in this booklet (see ‘urban forests’ and ‘street trees’ sub-sections), greenery has the ability to reduce stress levels, tension, and aggression in those nearby, and can elevate mood and restore attention. At a building level, these effects can have a positive effect on workers which can lead to enhanced performance and productivity. In a unique 2010 study of workplaces in Australia for example, researchers from the Sydney’s University of Technology found that introducing plants into the work environment led to a 37% reduction in symptoms of tension and anxiety, a Attention restoration Improved workplace satisfaction + productivityInterior VegetationHealth Benefit:Regular, visible interior plants in an office workspace has been shown to reduce mental fatigue, stress, and tension in employees, and boost workplace productivity and creativity. Photo by Nbuyoshi Shioda. University of Exeter (UK) which found that employee productivity increased by 15% when previously bare work environments were filled with houseplants 2. As one of the researchers behind this publication, psychologist Dr Chris Knight, explained in an interview with The Guardian, “what was important was that everybody could see a plant from their desk. If you are working in an environment where there’s something to get you psychologically engaged you are happier and you work better” 3.25Co-benefit:1 Craig, A., Torpy, F., Brennan, J., & Burchett, M.D. (2010). The positive effects of office plants. Nursery papers (6). Retrieved from Nieuwenhuis, M., Knight, C., Postmes, T., & Haslam, S. A. (2014). The relative benefits of green versus lean office space: Three field experiments. Journal of Experimental Psychology: Applied, 20(3), 199.3 Malik, S. (2014, September 1). Plants in offices increase happiness and productivity. The Guardian. Retrieved from 4 Plambech, T., & Van Den Bosch, C. C. K. (2015). The impact of nature on creativity–A study among Danish creative professionals. Urban Forestry & Urban Greening, 14(2), 255-263.5 Browning, B., & Cooper, C. (2015). Human Spaces: the global impact of biophilic design in the workplace. Retrieved from Lichtenfeld, S., Elliot, A. J., Maier, M. A., & Pekrun, R. (2012). Fertile green: Green facilitates creative performance. Personality and Social Psychology Bulletin, 38(6), 784-797.7 Madsen, S. (2019, January). Benefits of Plants in the Office: Increased Creativity. Wasatch Greenscapes. Retrieved from readings:CreativityIn addition to boosting workplace productivity, there is evidence to suggest that visual exposure to nature can stimulate creativity by increasing individual curiosity, concentration, flexible thinking, and the ability to take on new ideas and information 4.  According to a large international study of over 7,000 office workers from 16 different countries presented in The Human Spaces Report into the Global Impact of Biophilic Design 5, exposure to natural elements such as greenery within the workplace can enhance creativity by 15%. This enhanced creativity is likely facilitated by the attention restoration and subsequent improved mental functioning triggered by exposure to greenery, and the association of the colour green with growth – something that may subconsciously “evoke the motivation to strive for improvement and task mastery” (Lichtenfeld, 2012 6 as quoted in Madson, 2019 7). Part 3Building ScaleInterior vegetation inspiration.Images left to right sourced from W.M. McLendon; Greenery Unlimited; and Brabbu Design Forces.Sun. Water. Air. Sun.Water.Air.The focus of this booklet has been on the health benefits of a specific natural element, greenery. It is important to note however, that greenery exists as one part of a broader interconnected complex natural system. Greenery relies on sunlight and water for nourishment for instance, and is only able to grow in the right climatic conditions. At the same time, greenery is able to take in carbon dioxide from the surrounding atmosphere and convert it to oxygen, contributing to cleaner more breathable air. Greenery is able to enhance the ability of soil to absorb and retain water and nutrients, and as we have seen from the preceding chapters, provides a plethora of benefits to other living organisms. Humans are but one of many animal species that benefit massively from this natural element.  In addition to acknowledging that greenery operates in – and is sustained by – a wider natural system, it is important to highlight how other elements within this natural system can directly benefit human health too. As a concluding endnote to this booklet, the following section provides a brief high-level description of some of the ways three specific other natural elements – sun, water, and air – can contribute to human health and well-being. 29Part 4SunWaterAirSunWaterThe sun enables green plants to grow by providing solar energy which is converted into usable chemical energy through the process of photosynthesis.Water is necessary to sustain all life forms in some way. For greenery, water is a crucial ingredient in the process of photosynthesis which allows the conversion of carbon dioxide and water into new plant material (growth) and oxygen. Sunlight is a source of Vitamin D for humans. Vitamin D facilitates the intake of calcium and phosphorous in humans, and is a vital nutrient for bone growth and immune functioning. Numerous studies have highlighted the benefits of vitamin D for fighting off disease, including the likes of influenza and heart disease. Exposure to sunlight has also been shown to play a role in regulating mood and can contributed to mitigating depression and anxiety. Sunlight is important for calibrating human’s internal body clocks, and regular daylight exposure can facilitate healthy sleep patterns in adults and children.Relationship to greenery: Relationship to greenery: Human health benefits:30AirPlants need air to photosynthesis (which provides them with sustenance and energy to grow) and to breath.As well as being reliant on sufficient air to be able to survive, greenery plays an important role in improving the air quality for other living species by capturing carbon dioxide (carbon sequestration) and converting it into carbon and oxygen – the later of which is released into the atmosphere during photosynthesis. The amount of oxygen produced by an acre of tree coverage each year equates roughly to the amount of oxygen consumed by 18 people annually. The size of a tree directly influences its carbon storage and sequestration potential, with large evergreen trees able to store and convert carbon at a much greater rate than smaller types of vegetation. Due to their simultaneous ability to both mitigate bad air quality (by taking in carbon) and actively improve air quality (by producing oxygen), greenery provides a powerful tool for addressing the air pollution problem in most cities that is the cause of a huge number of respiratory related morbidities and mortalities. As with greenery, there is a growing body of literature documenting the therapeutic effects of blue spaces on humans. In particular, exposure to natural blue spaces such as rivers, lakes, and the sea has been demonstrated to benefit human mental health and psychosocial well-being and promote physical activity. Furthermore, blue spaces – and in particular the ocean and areas where rivers meet the sea – are a crucial food source for humans. Globally, fish provides almost 3 billion people with over 15% of their average per capita protein intake and in Europe, the average person consumes roughly 27 kg of seafood per year. Due to its crucial role in sustaining all lifeforms, water is seen as spiritually significant and sacred by many cultures around the world. In Maori culture for example, water is considered to be an important treasure (taonga) that possess a lifeforce (mauri) and has a spirit (wairua) which must be safeguarded.Responsible environmental stewardship over our oceans, lakes, and rivers is important for protecting this precious and often culturally significant life-supporting food source, and will enable future generations to benefit from the therapeutic and recreational opportunities provided by blue spaces.Relationship to greenery: Human health benefits:31Part 4SunWaterAirHuman health benefit:Conclusion:The primary goal of this booklet is to be informative in an accessible and easy-to-understand way. My hope is that through this document, you – the reader – will have gained a better understanding of the multiplicity of interconnected ways greenery can benefit human health, and the mechanisms behind these relationships. In other words, you will not only know how greenery benefits human health and well-being, but also why. In addition to increasing awareness, this booklet is intended to be a gentle call to action. By structuring this booklet into different chapters based on scale (city, neighbourhood, and building) and highlighting the benefits and co-benefits associated with different types of greenery, the reader will be able to recognize what is most applicable to them in there daily sphere of influence and everyday life, and ideally be motivated to act on this. For the general reader, this may be as simple as incorporated interior plantings into one’s home or becoming involved with a community garden or local green street initiative. For business owners, this could mean integrating biophilic design features into the workplace in order to boost employee satisfaction and productivity. For planners and designers, it could mean incorporating green ideas into their practice, whilst for politicians, it may be a matter of putting forth motions to increase access to greenspace or create new city parks. With a growing world population and an increasing shift to urban living, addressing some of the major current challenges faced by cities around the world – including climate change, structural inequality, housing affordability, and exposure to natural hazards – will require innovative, flexible solutions. Greenery does not provide all the answers, but it does have the potential to contribute to healthier, happier communities and cities in a meaningful, sustainable way. It is hoped that this booklet will be a useful resource for communities and individuals aiming to turn this potential into a reality.A Greener, Healthier Future?32


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