Health Benefits from Nature Experiences Depend on Dose

Just sitting on a park bench for 30 minutes a week will do.  I bet this will never make it into a stroke protocol to reduce your depression and high blood pressure. The inability to even do this tiny bit for stroke survivors tells you how fucking bad your stroke hospital is. Costs almost nothing except for transport to the outside.
http://www.nature.com/articles/srep28551

• Danielle F. Shanahan
• , Robert Bush
• , Kevin J. Gaston
• , Brenda B. Lin
• , Julie Dean
• , Elizabeth Barber
•  & Richard A. Fuller

• Scientific Reports 6, Article number: 28551 (2016)
• doi:10.1038/srep28551
• Download Citation
• • Environmental sciences
  • Risk factors
  • Urban ecology

Received:

05 February 2016

Accepted:

03 June 2016

Published online:

23 June 2016

Abstract

Nature within cities will have a central role in helping address key global public health challenges associated with urbanization. However, there is almost no guidance on how much or how frequently people need to engage with nature, and what types or characteristics of nature need to be incorporated in cities for the best health outcomes. Here we use a nature dose framework to examine the associations between the duration, frequency and intensity of exposure to nature and health in an urban population. We show that people who made long visits to green spaces had lower rates of depression and high blood pressure, and those who visited more frequently had greater social cohesion. Higher levels of physical activity were linked to both duration and frequency of green space visits. A dose-response analysis for depression and high blood pressure suggest that visits to outdoor green spaces of 30 minutes or more during the course of a week could reduce the population prevalence of these illnesses by up to 7% and 9% respectively. Given that the societal costs of depression alone in Australia are estimated at AUD$12.6 billion per annum, savings to public health budgets across all health outcomes could be immense.

Introduction

Urbanization is emerging as one of the most important global health issues of the 21^st century^1,2, with cities becoming epicenters for chronic, non-communicable physical and mental health conditions^3,4. There is growing recognition of the crucial role of urban green spaces in addressing this public health challenge^5,6, with over 40 years of research showing that experiences of nature are linked to a remarkable breadth of positive health outcomes. This includes improved physical health (e.g. reduced blood pressure⁷ and allergies⁸, lower mortality from cardio-vascular disease⁹, improved self-perceived general health^10,11), improved mental wellbeing (e.g. reduced stress¹² and improved restoration^13,14), greater social wellbeing¹⁵, and promotion of positive health behaviors (e.g. physical activity^16,17). Consequently, cities across the world are investing in the provision, management and enhancement of public green spaces, with the 100 largest cities in the US alone spending over US$6 billion in 2015¹⁸. Advice about how to achieve health outcomes from green spaces currently remains very general^19,20. Evidence on how frequent or how long nature experiences need to be, or what types of nature are needed, is vital to ensure that investment in green space provision can cost-effectively help to meet the public health challenges of urbanization^21,22,23.
Here, for the first time we use the nature-dose framework posed by Shanahan et al.²¹ to quantify the link between health outcomes and experiences of nature, as measured by intensity (i.e. the quality or quantity of nature itself), and the frequency and duration of a city resident’s experiences. We focus on examples of health issues across four domains for which there is some prior evidence that nature exposure can provide benefits. These health issues are also particularly relevant for cities, and include mental health (the prevalence of depression), physical health (high blood pressure), social wellbeing (social cohesion), and a positive health behaviour (physical activity). These health outcomes could be tied to experiences of nature through a range of mechanistic pathways (some of which are outlined in Fig. 1)²². For example, a higher level of vegetation within a landscape (a measure of nature intensity) may be linked to enhanced physical, mental and social wellbeing through providing a visually complex environment that can lead to reduction in stress²⁴, reduction of mental fatigue²⁵, or by adding to the look and feel of a place and so providing a pleasant location for social or physical activities²² (Fig. 1). Similarly, variation in duration and frequency of nature exposure could also influence the long-term health outcomes people experience, with even short-duration exposure to natural environments shown to deliver an immediate reduction in blood pressure⁷ and greater feelings of restoration²⁶. Yet despite this, whether and how the intensity, frequency or duration of nature exposure leads to long-term and lasting effects on health remains unexplored.