A scoping review will be conducted to identify the barriers and facilitators associated with the 24 utilisation of green and blue spaces. The review will follow the PRISMA-ScR guidelines, in addition to the 25 associated Cochrane guidelines for scoping reviews. A literature search will be performed across five 26 databases, and articles will be selected based on key inclusion/ exclusion criteria. All data will be extracted to 27 a pre-defined charting table. The primary and secondary outcomes will be mental and physical health 28 respectively. 29
This review will better inform relevant stakeholders of the potential enablers and barriers of nature-31 based interventions, and thereby improve provision and implementation of NBIs as public health initiatives. 32
Ethics and Dissemination 33 . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
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The copyright holder for this preprint this version posted July 4, 2020. In 2017, 792 million people worldwide lived with a mental health disorder (1), defined as 61 "syndromes characterized by clinically significant disturbance in an individual's cognition, emotional 62 regulation, or behaviour that reflects a dysfunction in the psychological, biological, or developmental 63 processes that underlie mental and behavioural functioning" (ICD-11, 2020) (2). This growing 64 prevalence of poor mental health has both direct and indirect costs, and in financial terms, is 65 estimated at between £70-100 billion annually for the United Kingdom (UK) alone (3).
A growing body of evidence suggests that nature-based interventions (NBIs) could be a cost-67 effective solution to improve mental health outcomes, while also addressing the increasing demand 68 from patients for less intrusive treatment options (4) . Indeed, contact with nature has been shown to 69 reduce stress and improve self-reported emotions, as well as increase attention capacity, happiness, 70 and vitality (5, 6, 7). It has also been shown to improve physiological outcomes such as longevity 71 and self-reported health (8).
Over time, NBIs have been referred to as 'green care', 'ecotherapy', 'social prescribing' or 73 'green prescribing', demonstrating the lack of consensus on terminology in this field (6). 'Blue 74 prescribing' is also increasingly considered a part of NBIs, since water environments (e.g. river, 75 coastlines) are as much a part of nature as green spaces (e.g. parks, public open spaces) (9). Zealand and Scotland as a means to improve mental health. While this is a positive step, NBIs rely 88 nonetheless on patients being able to access green and blue spaces (10). Yet, environmental (i.e. 89 quality, land management) and socio-structural barriers (i.e. socio-economic status, public transport 90 infrastructure etc.) to green and blue spaces limit the accessibility of NBIs in rural and urban areas 91 (12). Consequently, a scoping review will be conducted to assess how the barriers to the utilisation of 92 green and blue spaces influence the effectiveness of nature-based interventions.
. CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review)
The copyright holder for this preprint this version posted July 4, 2020. interventions and the lack of consensus surrounding their application. This systematic search 120 strategy will include free text and subject heading terms, adapted to each of the databases.
. CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
The copyright holder for this preprint this version posted July 4, 2020. . https://doi.org/10.1101/2020.07.03.20145946 doi: medRxiv preprint . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
The copyright holder for this preprint this version posted July 4, 2020. . https://doi.org/10.1101/2020.07.03.20145946 doi: medRxiv preprint 6 deemed to sit on the border between inclusion and exclusion. Duplicates will be removed from the 137 search at both screening stages.
The inclusion criteria for this scoping review are intentionally broad since this is an emerging 139 field, and the authors anticipate few studies, both narrow and broad in scope. To be included, studies 140 must can be either human-centric or review articles with reference to green or blue spaces and a 141 health perspective. Considering the contemporary topic of this scoping review, only studies from 142 1980 onwards will be included. Studies must also be published in either French of English due to the 143 absence of additional translational capacity.
Excluded studies will be those that do not fit the inclusion criteria and only report on either 145 NBI exposure or health outcomes alone. Studies will also be excluded if they were conducted before 146 1980. This should ensure that all relevant studies to the research question are included and analysed 147 accordingly, as well as a number of literature types described in Table 1 below. . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
The copyright holder for this preprint this version posted July 4, 2020. Thematic content analysis will be performed to group findings in categories sharing 158 similarities. This will be performed by one researcher and reviewed by the research group. Any 159 amendments to this scoping review protocol will be documented with reference to saved searches 160 and analysis. is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
The copyright holder for this preprint this version posted July 4, 2020. Wellbeing is developed through STH when individuals actively participate in gardening activities or by doing something (i.e. growing food). HT was an add-on to therapy for many years and its use increased since the 1980s, when numerous garden projects offering both STH and HT were developed in the UK. Food growing as a treatment intervention is another alternative.
Care farming (or social farming) is the therapeutic use of agricultural landscapes and farming practices. Health, social and educational care are provided by using components of the whole of part of the care farms, within a supervised, structured programme of farming-related activities.
Facilitated environmental conservation work delivers health, wellbeing and social benefits for vulnerable groups. As commissioned programmes, these are considered a form of NBI. Their facilitated and structured activities are designed for: 1) the conservation and management of natural places; and 2) for the health and wellbeing of participants.
AAI utilises animals in the rehabilitation or social care of humans. AAI includes: 1) AAA -activities with animals and having a therapeutic effect and 2) the more formal Animal Assisted Therapy (AAT) -a goal-directed intervention animals are the most important part of the treatment process being directed, documented and evaluated by professionals.
Green exercise therapy as a treatment option refer to individuals actively participating in green exercise activities (i.e. walking), which are facilitated and led by an instructor. Example: 'Walking for Health' in the UK (12).
Ecotherapy uses activities/exercises to emphasise "mutual healing and growth" between human and nature on enhancing one's wellbeing; to promote positive action on the environment and improve community wellbeing.
The immersion in natural, wild and/or wilderness settings provides many . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
The copyright holder for this preprint this version posted July 4, 2020. . https://doi.org/10.1101/2020.07.03.20145946 doi: medRxiv preprint health and development opportunities. Typically, this form of therapy is supervised by trained healthcare professionals who would: i) use nature as 'cotherapist'; and ii) use therapeutic activities in a wilderness location. OR (nature therapy)) OR (outdoor therapy)) OR (green spaces)) OR (green skills)) OR (green social care)) OR (nature-based therapy)) OR (green prescribing)) OR (green prescriptions)) OR (social prescribing)) OR (green exercise)) OR (green interventions)) OR (green health)) OR (ecotherapy)
Search: (((((((((((blue care) OR (blue spaces)) OR (blue interventions)) OR (naturebased interventions)) OR (social prescribing)) OR (blue prescriptions)) OR (blue prescribing)) OR (blue therapy)) OR (blue skills)) OR (blue activities)) OR (blue exercise)) OR (blue interventions)
Search: ((((((((((((((((((((((mental health) OR (EQ-5D)) OR (wellbeing)) OR (lifesatisfaction)) OR (happiness)) OR (emotion)) OR (mood state)) OR (stress)) OR (anxiety)) OR (depression)) OR (GAD-2)) OR (GAD-7)) OR (PC-PTSD-5)) OR (PHQ-2)) OR (PHQ-9)) OR (HDRS)) OR (SF-36)) OR (GHQ)) OR (questionnaire)) OR (formal diagnosis)) OR (diagnosis)) OR (self-esteem)) OR (loneliness)
Search: ((((((((((physical health) OR (physiological health)) OR (bmi)) OR (waistcircumference ratio)) OR (cardiovascular health)) OR (blood pressure)) OR (heart rate)) OR (MRI results)) OR (pulse rate)) OR (cholesterol)) OR (cortisol)
Search: ((((((((((age) OR (income)) OR (sex)) OR (ethnicity)) OR (socio-economic status)) OR (social gradient)) OR (deprivation)) OR (geography)) OR (employment)) OR (social determinants)
Search: (((((((((((((biodiversity) OR (access)) OR (accessibility)) OR (quality)) OR (safety)) OR (crime)) OR (infrastructure)) OR (public transport)) OR (individual will)) OR (motivation)) OR (pollution)) OR (temperature)) OR (weather)) OR (distance)
. CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review)
The copyright holder for this preprint this version posted July 4, 2020. . https://doi.org/10.1101/2020.07.03.20145946 doi: medRxiv preprint