Background and aims
There is growing evidence that green and blue outdoor spaces positively impact mental health and well-being. Impact occurs through mechanisms such as increased social contact, cognitive improvement, reduced stress and psychological recovery.1–5 Green and blue space (GBS) may also mitigate environmental stressors such as urban noise and poor air quality.6,7 Currently, there is limited evidence for a causal relationship between the ‘greenness’ and ‘blueness’ of environments and adult mental health;5,8 a key limitation being the lack of longitudinal studies.9 We present the largest, most comprehensive, longitudinal evaluation of the impact of changes in exposure to GBS on mental health and well-being among adults in Wales. We conducted this study in Wales due to the mechanism allowing dynamic linkage of environmental metrics to individual’s health data for the population of Wales, within the Secure Anonymised Information Linkage (SAIL) databank.10
Mental health and well-being
Mental health is defined by the World Health Organization (WHO) as ‘a state of well-being in which every individual realizes his or her own potential, can cope with the normal stresses of life, can work productively and fruitfully, and is able to make a contribution to her or his community’.11 Wellbeing is a complex multidimensional concept typically considered to evaluate whether or not life is worthwhile and has purpose.12 Subjective well-being is an important marker of quality of life, and is related to mental and physical health outcomes, including survival.13–15
Mental ill-health is one of the main contributors to the non-fatal global disease burden. It accounts for between 21.2% and 32.4% of years lived with disability,16,17 and impacts all age groups.18 In the UK, the Adult Psychiatric Morbidity Survey found that more than one-fifth of adults (aged 16 years or over) live with a common mental health problem.19 In addition, almost half (43.4%) of UK adults report a diagnosable mental health condition at some point in their life, with rates higher in women than men (51.2% and 35.2%, respectively).19 The 2015 Welsh Health Survey found that 13% of Welsh adults (aged 16 years or over) were currently receiving treatment for a mental health disorder.20
Mental ill-health poses a significant burden on health and social care systems. It costs the UK economy an estimated £70–100 billion per year, around 4.5% of the gross domestic product.21 In Wales, over 2007–08, the costs of mental ill-health (£7.2 billion) outweighed the health and social care costs of all other forms of illness (£6.1 billion).21 In this study we refer to common mental health disorders (CMDs) that comprise anxiety and depressive conditions that are generally treated by a general practitioner (GP).
Green and blue spaces
Blue spaces are dominated by a watery element, such as a lakeside, river or coast. Green spaces may include a watery element but are characterised by predominantly ‘green’ elements such as grass or trees. Green spaces, and the networks of those spaces, are defined by Natural Resources Wales (NRW)22 as a:
shorthand for both vegetated land-parks, community gardens, trees, woodlands and hedges, informal spaces, allotments and food growing sites, areas of water, such as rivers, canals, lakes and ponds and the sea shore. Green infrastructure describes the network created by all these spaces.
Green or blue spaces maybe be highly managed, such as urban parks, or more ‘natural’ spaces, such as native woodland. There is not necessarily an assumption of ownership and access rights; typically, this will be defined if relevant (e.g. ‘publicly accessible green spaces’ could refer to an urban park). The language used to describe environmental specifics varies but without a discernible pattern according to discipline or context.23 Terminology also varies according to the intended ‘use’ of a space or resource. We use the terms ‘green space’ and ‘blue space’, defined as spaces dominated by natural elements, in either rural or urban contexts, with green and blue space hereafter abbreviated ‘GBS’. Chapter 3 presents the comprehensive, spatially nested typology of GBS developed for this study.
Green and blue space and mental health and well-being
Green space
Reviews have shown that exposure to green space can promote life satisfaction,24 aid psychological restoration25 and mitigate the impact of stress.26 Views of green space from the home have been linked to measures of subjective well-being, and there are relationships between positive mental health in adulthood and overall greenness of the living environment,5 residential proximity to GBS27,28 and frequency of green space visits.29,30 However, these relationships are not necessarily straightforward. The complexity of characterising exposure to green spaces and the pathways through which they affect mental health means that causal relationships are not always clear.8,31 Most caution that the evidence is currently limited and often inconsistent.8
Factors such as age, sex, physical activity, ethnicity and socioeconomic status appear to moderate relationships between exposure to green space and mental health outcomes in adulthood.27,32,33 The associations between greener living environments and mental health appear to vary over the life course34 and there is little consistency according to gender.35 Green space may be of greater benefit to people from disadvantaged groups and living in more socioeconomically deprived areas compared with those in less deprived areas.8,27 Again, this is not a straightforward relationship and is not consistently statistically significant in studies investigating the effects of socioeconomic status.31 Less is known about interactions between ethnicity and the salutogenic effects of green space exposure, but a UK birth cohort study showed that ethnicity moderated relationships between residential green space and mental well-being.33
Blue space
The hazardous qualities of blue spaces are well known, but their salutogenic public health implications have, until recently, received less scientific attention (and less than those of green space).36,37 There is a growing body of evidence that exposure and proximity to blue space is linked to positive mental health and well-being.38 Living near the coast is shown to have general mental health benefits.4,39 There is also evidence that people living near (or with views of) the coast experience lower psychological distress.40,41 Epidemiological studies do not typically distinguish between coastal and freshwaters,41 but there is some evidence that proximity to inland water also yields positive mental health effects.42,43
Mediators and moderators of relationships between blue space and mental health are less well understood than those for green space, but it is likely that similar factors apply. For example, a 2019 study in England showed that the mental health benefits of residential coastal proximity appear to moderate the effects of low socioeconomic status.44 Physical activity also appears to be a mediator between positive mental health and coastal proximity. This effect is limited to terrestrial physical activity near the coast rather than ‘watersports’.43
Quantity, proximity, quality and type of green and blue space and mental health and well-being
The amount of green space in an area has been linked to good population mental health4,45 and reduced inequalities in health in the UK.44 However, there is insufficient evidence to dissect how type, proximity, quantity and ‘quality’ (either ecological or in terms of maintenance) or ‘qualities’ (the characteristics) of green or blue space each influence population-level mental health and well-being.46 Most available evidence linking GBS to health outcomes considers relationships at a local area level, typically the total amount of green space around residences, with no assumption about type, quality or usage.5
The type, quality, and qualities of GBS may be significant in the context of mental health benefits. Individual studies suggest that environment (or landcover) type is an important consideration for general and mental health.3,39,47,48 In urban settings, gardens and allotments are notably beneficial for mental health.49,50 The impact differs according to the type of garden, with private spaces appearing to be most strongly associated with better outcomes.51 In other studies, proximity to specific types of environments, such as coasts, have been found to be linked to better mental health.44
The impacts of GBS ‘quality’ on mental health and well-being are more difficult to assess, given the breadth of meaning that can be attached to this term. We consider ‘quality’ as the state, whether ecological or physical, of the green or blue space. ‘Qualities’ refers to the characteristics, or composition of the space. GBS ‘quality’ and ‘qualities’ are multidimensional concepts. They may be defined and assessed subjectively (e.g. perceived ecological quality, perceived safety) or objectively (e.g. public facilities, air pollution levels) in a number of ways. Evidence of links between indicators of GBS quality and mental health is limited.27,52 However, there are some studies supporting ‘quality’ and ‘qualities’ of GBS as important components for mental health and well-being impacts. General satisfaction with local green space is important,33,53 and perceptions of safety and maintenance determine people’s use of green space.54,55 Public accessibility and related urban planning influence the likelihood of the use and resulting experience of spaces, impacting potential health gain.53,56 The relative biodiversity of environments may also play a role, particularly in terms of the types of nature people experience,57,58 but evidence is limited and inconsistent.59
Overall, the type, proximity, quality, and qualities of GBS are likely to be important in the context of mental health benefits. However, current evidence is inconsistent for relationships between the: quantity,5 type60 and quality and qualities of GBS,27 and mental health and well-being.
Use of green and blue spaces
The studies mentioned previously often make no assumption about usage of the GBS. Usage of a space is theorised to be a factor in potential benefit;61 however, actual visits to, and time spent in, GBS are less well studied.5 Studies have, however, shown that recreational use of GBS is associated with multiple mental health outcomes.62,63 Further, there are indications that minimum weekly baselines of time spent in green spaces are linked to well-being and good mental health.63 Whether or not physical activity mediates benefit has been investigated in a number of studies, with mixed results.64
System-wide impacts of green and blue spaces
Additional pathways may link the presence of GBS to mental health. These include the mitigation or avoidance of the effects of urban heat islands, air and noise pollution, and flooding.46 Although evidence is limited in terms of demonstrable associations of these pathways with better mental health,65 some linkages have been demonstrated; for example, green spaces were found to be associated with reduced psychological distress from local noise pollution.66 Thus, there are likely to be multiple benefits of GBS, impacting our physical and mental health through indirect mechanisms within wider ecological systems.
Inequalities
There are inequalities in the distribution and accessibility of good quality GBS in the UK. People in deprived areas, minority ethnic communities, elderly people and those with long term poor health and disabilities often have less (physical) access to good quality green spaces. They tend to use green spaces less and are more likely to have negative perceptions regarding their usage of such spaces.67–69 These groups also tend to have poorer health outcomes.70,71 However, there is cross-sectional evidence suggesting that health inequalities are lessened with greater proximity to green or blue spaces.44,72,73
Policy context: green and blue space and mental health and well-being
Addressing the causes of poor mental health, promoting solutions and reducing burden to individuals, communities and society is a key concern for the UK and Welsh governments. Where we live, learn, work and play are determinants of mental health and influence key risk factors.74 As such, the relevance of place to mental health is recognised across contemporary policy and service delivery strategy in Wales, as it is across the UK, and is embedded within decision-making frameworks such as the Well-being of Future Generations (Wales) Act.75
The Healthier Wales strategy notes the importance of living and working conditions on health outcomes.76 The strategy details a ‘whole systems’ approach to health promotion and protection in Wales, recognising that health services are only one element of what determines health. This systems approach is reflected in the Well-being of Future Generations (Wales) Act.75 The Act requires public bodies, including the health and environmental services, to work together to address health, inequalities and living conditions. It also identifies a set of ‘well-being’ goals that all public bodies must work to achieve and requires these bodies to consider the long-term impacts of their decisions, including how these relate to the well-being of people in Wales. The Act and associated guidance highlight the need to ensure equitable provision of good quality living environments, including green and biodiverse spaces, for health. The decision-making frameworks associated with the delivery of the Act, especially the public services boards, are intended to reflect these interdependencies, ensuring that health impacts of decisions relating to the environment, and vice versa, are fully considered.
The importance of the natural environment, and green or blue spaces, in meeting these well-being goals is reflected in national policy. For example, the Welsh Together for Mental Health strategy states that natural environment can have significant positive impact on physical and mental well-being, noting that access is positively related to a number of mental health, developmental and behavioural outcomes and risk factors.75
Creating an Active Wales77 highlights the role of green space provision in supporting population physical activity.
The importance of place, and particularly green or blue spaces, to health is similarly reflected in the policies and strategies of NRW. NRW’s Outdoor Recreation and Access Enabling Plan 2015–2020 details the health benefits of outdoor recreation.22 The plan aims to increase appreciation and use of the natural environment to improve people’s health and well-being. They aim to deliver impact by ensuring equitable access to spaces, promotional and engagement activities, and through partnership working such as with the planning services. NRW’s State of Natural Resources Report 2016 suggests increasing green infrastructure (trees and green space) and increasing woodland cover as key for sustainable management of natural resources and the well-being of people in Wales.78
NRW’s Managing Today’s Natural Resources for Tomorrow’s Generations79 includes the aim ‘to make better use of local green space in both urban and rural areas the norm, together with a recognition that physical activity in the outdoors contributes to the prevention of many physical and mental illnesses’. Proximity to accessible green space and physical activity in the outdoors and its link to physical and mental health are identified as key indicators. NRW’s Improving Access for All policy acknowledges and pledges to tackle potential inequalities in access to GBS.80
In Welsh planning policy Facilitating Accessible and Healthy Environments is one of the five key national sustainable placemaking outcomes and has the specific ambition to provide ‘accessible and high-quality green space’.76 The strategy emphasises the role of GBS within wider networks of green infrastructure. It highlights the potential to enhance health and well-being through providing a context for physical activity, higher-quality living environments and quiet tranquil areas.
Evidence gaps and requirements
Decision makers at all scales, and from multiple sectors (public and third especially), are seeking effective evidence-informed ways to provide, manage and promote GBS for health. England’s Department for Environment, Food and Rural Affairs, for example, recently committed to investing in research to inform their service delivery, and in the provision and use of natural environments for health outcomes.81
NRW’s first State of Natural Resources Report 2016 explicitly linked Wales’s natural resources to the well-being of people in Wales.78,79
Improved evidence on the relevance of green or blue spaces to mental health is required to inform planning and area regeneration in the UK, which shape the environments people are exposed to. While there is a substantial body of evidence indicating the benefits of GBS for mental health and well-being, there are limitations to the existing evidence-base. There are high levels of heterogeneity between studies, in measures of GBS exposure and mental health and well-being outcomes, limiting the potential for robust meta-analyses.82 There is also a lack of evidence relating to certain population subgroups and potential pathways. There is insufficient evidence for determining the most appropriate size, location, configuration, connectivity, composition and characteristics of GBS for mental health outcomes.82
There are few longitudinal studies on either change in GBS exposure though time or on the impact of visiting GBS over the life course. In cross-sectional studies, which currently provide much of the evidence on the relationships between GBS and mental health and well-being, the direction of relationships is not always clear. For example, cross-sectional studies may be unable to determine whether green space exposure leads to good mental health, or if people with good mental health visit green space more often. Longitudinal studies enable a sequence of events to be constructed (e.g. mental health measured prior to and following a change in exposure), allowing for more confident inferences regarding causality.83 The small number of studies using longitudinal data are beginning to help unpick the causal direction of impact.45,84
There is evidence that public health interventions are cost effective in reducing health service expenditure,85 but evidence relating to nature-based interventions is limited,86,87 particularly in the context of mental health. Systematic synthesis of nature-based interventions is difficult due to plurality in valuation methodologies, but emerging evidence suggests significant value to health and social systems.86 Urban green spaces in the United States have been estimated to be worth between US$2.7 and $6.8 billion annually (2012).88 Physical activity taking place in natural environments in England has been estimated to be worth £2.18 billion in welfare gains,89 with a substantial proportion (£176 million) potentially derived from activity in marine environments.90 Natural areas must be accessible for such benefits to be gained. Pedestrian infrastructure, such as the Wales Coast Path, encourages physical activity leading to health benefits with high economic value, estimated at £18.3 million annually.91
Aim and objectives of the project
We aim to create novel linkages between environment and health data to enable quantification of the impact of exposure to GBS through time for a national population.
This project will address evidence gaps by:
Our project will also contribute to addressing the evidence needed by our project partner, NRW, for ‘place-based assessment of potential changes, both positive and negative, to the “total health impact” (mental, physical and well-being) arising from future land management options’.92 We will also produce findings to underpin future interventions, for example estimating effect sizes for interventions aiming to increase frequency of visits to GBS.
We deliver this project through a series of objectives, using data from a national population, and a nested survey sample.
National population dataset objectives
Create a longitudinal dataset of residential
GBS exposure data for all homes in Wales using UK Ordnance Survey (OS), local authority and remotely sensed satellite data.
Create an 11-year dynamic cohort of individual-level longitudinal residential
GBS exposure to answer the questions: ‘Is a greater residential exposure and access to
GBS associated with the likelihood of seeking help for a
CMD in general practice?’ and ‘Is the association between exposure, or access to,
GBS and seeking help for a
CMD modified by socioeconomic disadvantage and moving home?’
Survey dataset objectives
Create longitudinal, environment, health and demographic individual-level data linkages between survey and routine data within the
SAIL databank.
Utilise the data-linked National Survey for Wales (NSW) to answer the question: ‘What is the impact of
GBS residential exposure, modified by
GBS use and multiple socio-physical modifiers, on well-being and CMD?’
The national population dataset uses routinely collected health and demographic data (data collected for purposes other than research). The survey sample dataset links routine data in the SAIL databank with in-depth survey responses from the NSW. Both consider socioeconomic health and well-being inequalities.
Synthesising objective
To translate results into policy recommendations for government and disseminate results from health outcome and economic impact assessment to academics, stakeholders, and policy makers.
