Nature–Based Interventions for Improving Health and Wellbeing: The Purpose, the People and the Outcomes

1There are many pressing public health and environmental challenges associated with modern living, with rapidly growing levels of chronic, non–communicable physical and mental health conditions and global recognition of serious health risks posed by stressful living conditions. Engagement with nature is a common pursuit in cities and it is becoming increasingly recognised as a means to alleviate many of these challenges. Evidence now points to benefits for physical health (e.g., lower prevalence of high blood pressure and allergies), mental health (e.g., lower prevalence of depression and anxiety) and social wellbeing outcomes for people who spend time in nature. Moreover, there is evidence that the magnitude of such benefits can increase with the dose of nature. It is thus of significant concern that urbanisation and the challenges of modern life are leading to reduced engagement with the natural environment.

2To counter this development, nature–based health interventions (NBIs) can facilitate change through a somewhat structured promotion of nature–based experiences. NBIs are programmes, activities or strategies that aim to engage people in nature–based experiences with the specific goal of achieving improved health and wellbeing. For example, environmental manipulations where green and blue spaces are incorporated into cities can have positive outcomes associated with the management of habitats and flow of ecosystem services to people, but there is also a growing body of evidence highlighting the potential of green space for the treatment and prevention of physical, mental and social health and wellbeing challenges. This recognition that experiences of nature can provide benefits for people represents a major shift in public health thinking for both the prevention and the treatment of health issues, beyond considering nature solely as a risk–factor (e.g., through the transmission of insect–borne diseases).

3Reflecting the growing body of research demonstrating a link between interactions with nature and health, many governments, non–government organisations, public and private stakeholders are now beginning to consider these potential benefits in their policy and planning frameworks. Indeed, across the world, many NBIs are being implemented. These include, for example, minimum area targets for public green space and ‘nature prescriptions’, where doctors or other health practitioners prescribe nature–based experiences for patients living with specific health conditions. However, despite this growing movement, there is a dearth of guidance as to what NBIs are available and what specific health outcomes they might achieve and for whom. This can only limit the potential leveraging of natural settings to improve health and wellbeing outcomes for individuals and communities, potentially leading to inefficient and ill–targeted investment decisions.

4Here, we used expert elicitation to identify a range of NBIs that have been examined in the peer–reviewed scientific literature. This list of interventions is intended to provide a resource for decision–makers in government, non–government organisations, and other interested groups by outlining possible interventions, the potential health outcomes, and the target beneficiaries.

5We used a Delphi expert elicitation process to develop and then to refine and improve a list of NBIs that have received attention in the peer–reviewed scientific literature to date (Figure 1). The Delphi technique is an iterative method for building consensus. In this case, it was based on three rounds of questionnaires. Before the rounds of questions began, D.F.S. carried out a broad–reaching Web of Science literature search (initial search terms including ‘nature AND health OR wellbeing’, ‘nature–based health interventions’, ‘nature interventions’). The goal of this search was not a comprehensive review, but to develop a list of interventions—that is, programmes, activities or strategies that aim to engage people in nature experiences with the specific intention of improving health and wellbeing outcomes. The articles identified through the initial search were assessed, and NBIs identified where possible; further articles were found through the reference lists within the initial article set.

6Round 1. In the first round, experts were asked to review and refine the list of interventions to ensure that those with similar methods but different names were removed. Experts were also invited to add intervention types and provide example references. Experts also commented on the definition, goals, and target beneficiaries of each intervention and identified further relevant literature. Thirty experts were invited to contribute. All are scientists and/or health practitioners actively publishing peer–reviewed research on the connection between people, nature and health and wellbeing. Nineteen participated.

7Round 2. Following the initial review process, the comments were compiled and summarised by D.F.S. This involved the revision of text to improve accuracy and incorporate new information from experts. This revised list was recirculated to all 19 experts, and they were invited to agree or disagree with the content. The experts were also provided with their own original comments during this step. At this point, the experts were also invited to answer further questions on four specific intervention types for which a significant body of literature was available and for which the panel of experts had specific expertise. The questions focused on the reach of the interventions, barriers to individuals and organisations in implementing the interventions and potential unintended negative consequences.

8Round 3. The intervention list was again revised by D.F.S. on the basis of all comments made, involving addition of detail and refinement of definitions and other text. Some experts provided significant in–depth detail that went beyond the scope of this study, and in these instances, the detail was summarised. All responses from round 2 were anonymised and recirculated to all 19 experts again to review their own answers on reflection of other expert’s answers and ensure that the revision conducted by D.F.S. accurately reflected their views and that a consensus had been reached. They were also invited to add final thoughts triggered by the comments that had been put forward by their peers.

9All comments were synthesised to produce the final list presented in this article.

10Nineteen of 30 invited experts who were identified from across the world actively engaged with a Delphi expert elicitation process to review a compilation of NBIs identified through a literature search conducted by D.F.S. The 19 experts who participated in the review are all named authors on this paper. They represent a diversity of disciplines and areas of expertise relevant to the broad field of nature and health. Geographically, representation in the panel was particularly good from the United Kingdom and Oceania, while there were gaps in representation from Europe, Asia, Africa and the Americas. This was in part related to the availability of the identified experts to participate and in part, to difficulties in identifying experts who do not publish in English–language peer–review journals. The representation of national/cultural contexts in the literature reviewed, however, extended beyond those in which the 19 experts are situated.

11Twenty–seven distinct NBIs that have received some peer–reviewed research attention were summarised using the expert elicitation process (Table 1 and Table 2). Interventions were excluded from the list where health and wellbeing outcomes were not explicit goals (e.g., programmes that solely aimed to connect people with nature without the intention of also delivering health and wellbeing benefits).

12The intended outcomes and target beneficiaries varied widely across interventions, from the promotion of wellbeing and the prevention of chronic or lifestyle–based health conditions (e.g., through the provision of public parks) to targeted treatments for people living with specific health conditions (e.g., nature prescriptions for reducing high blood pressure). A categorisation of the different interventions is given in Figure 2; some aim to change the environment in which people live (e.g., providing new or better quality public green spaces; Table 1) and work (e.g., hospital, workplace), and others aim to change people’s behaviour and their interactions with nature (e.g., nature play/wild play programmes; Table 2 and Figure 2). There was some overlap in these categories where people engaged in nature–based activities through interventions that also involved enhancing the environment (e.g., ‘green gyms’ or environmental volunteering; Table 2).

13A closer investigation of barriers and potential negative implications for four intervention types was carried out, specifically, green prescriptions, wilderness therapy, green gyms and outdoor exercise groups (Table 2). There were a number of commonalities in the barriers, which included knowledge of health practitioners and lack of access to the intervention (especially where it relied on having transport or could not be completed independently as it relied on a specific organised programme). There were also some potential unanticipated negative implications, with risks of physical injury a common theme.

14The scientific literature includes studies on a diverse suite of nature–based interventions through which ill health might be prevented, health and wellbeing can be promoted, and/or specific illnesses might be treated. These interventions could provide a useful tool for enabling and encouraging people to engage with nature and, in doing so, potentially receive a multitude of physical, mental and social health benefits. Broadly speaking, the interventions identified in this study can be grouped into actions that change the environment in which people live, work, learn, recreate or heal, and those that change people’s behaviour through programs or other means. Because of this, the scale of impact varies from the population to the individual level and in the level of effort needed to achieve outcomes. Consequently, the selection of one intervention over another or the composition of a suite of interventions, must reflect the capacity and skills of the administering organisations, the goals of the activity or activities, as well as the needs of the population or the individual.

15A key feature of nature–based health interventions is that a single intervention can affect people in multiple ways and, therefore, potentially improve wellbeing across a range of domains. For example, nature prescriptions can both promote physical activity leading to many positive health outcomes, while also providing patients with the mentally restorative effects of natural spaces. Thus, investment in interventions can achieve significant outcomes across multiple domains and, when scaled up, could have significant and cost–effective implications for population health. Furthermore, nature can be pro–actively planned into city development activities to provide a protective factor against many health conditions. Research into the extent and magnitude of these outcomes is critical to assist decision–makers (such as hospital or care–home managers and urban planners) in weighing up the costs and benefits of investing in the various options, identifying ways to coordinate efforts (e.g., with regard to the siting of health care facilities) and ultimately supporting ‘prevent–to–save’ initiatives.

16As with other public health interventions, there are many factors that influence both the effectiveness and the success of NBIs. For example, the accessibility of public parks will inevitably influence their use by communities, and a number of studies have found people are more likely to exercise in neighborhoods with greater levels of park availability. There are also social equity issues at play. For example, disadvantaged neighborhoods have been repeatedly found to have less vegetation cover, fewer public parks and fewer street trees; additionally, organised user–pays programmes may be inaccessible for some disadvantaged sectors of society. Furthermore, the physical and mental capability of participants is a potential barrier to accessing some intervention types, as identified in this expert elicitation study. Social factors, such as acceptability of the intervention to local communities, are also likely to have an important influence on the uptake of nature–based health interventions; for example, several studies have now found that cultural differences have a critical influence on the use of public green spaces. Finally, an individual’s age, gender and other factors will play a role, as will perceptions of nature and the appropriateness of the nature setting in its wider context (e.g., ecological characteristics of the nature setting, facilities and infrastructure, programmed activities and experiences of social inclusion in the setting).

17As NBIs are not yet mainstream within the health care community, practitioner buy–in and knowledge was identified as a particular challenge in this study. Further knowledge and communication about the effectiveness of interventions gained from rigorous research is therefore likely to be an important precursor for their use, including understanding the limitations or barriers to success and accounting for local contexts. Active evaluation and communication of findings from relevant studies is needed to build more solid foundations for decision–making that will help improve health and narrow health inequities. This said, much is already known about the potential benefits and how they are realised, and public appreciation for parks and other NBIs has such long–standing support that many generations of urban residents have already been able to benefit from their availability.

18In this study, we used an expert elicitation process to compile a list of the nature–based health interventions that have received some research attention. This process is not without its limitations. Most notably, some interventions may have been overlooked, and the list was subject to a consensus on grouping and categorisation that others may have done in a different way. Furthermore, this study has thus not systematically addressed issues of intervention efficacy, effectiveness, and efficiency. While systematic analyses of efficacy and efficiency are as yet not possible for many intervention types because of a high level of variation in the methods used, outcomes measured within the literature to date (but see, e.g.,), and co–benefits realised by indirect means (e.g., parks along rivers may support nature experiences and also protect homes from flooding), such evaluations will be important avenues for future research. Finally, it bears mentioning that the recognition of the possibilities with nature–based interventions is engendering considerable innovation, as with the development of therapeutic gardens for new client groups (e.g., war veterans) and the use of nature experience to support the acquisition of mindfulness meditation techniques.

19We have identified a suite of NBIs that can be used to improve population health and wellbeing, and to address specific physical, mental and social health issues. The identified interventions broadly fall into two categories: those that change the environment, and those that change behaviours. The selection of an intervention will require the consideration of a range of factors, including cost, likely benefit, accessibility (including availability and social acceptability) and the capacity of the organisation to deliver it. Most importantly, however, the needs of the community or the individual and the goals of the intervention must be considered. To integrate nature–based health interventions into public health and planning policy, strong evidence for their effectiveness is important, and thus evaluation should be carefully built into new interventions.