Health benefits from nature experiences depend on dose

Nature within cities will have a central role in helping address key global public health 3 challenges associated with urbanization. However, there is almost no guidance on how much 4 or how frequently people need to engage with nature, and what types or characteristics of 5 nature need to be incorporated in cities for the best health outcomes. Here we use a nature 6 dose framework to examine the associations between the duration, frequency and intensity of 7 exposure to nature and health in an urban population. We show that people who made long 8 visits to green spaces had lower rates of depression and high blood pressure, and those who 9 visited more frequently had greater social cohesion. Higher levels of physical activity were 10 linked to both duration and frequency of green space visits. A dose-response analysis for 11 depression and high blood pressure suggest that visits to outdoor green spaces of 30 minutes 12 or more during the course of a week could reduce the population prevalence of these illnesses 13 by up to 7% and 9% respectively. Given that the societal costs of depression alone in 14 Australia are estimated at AUD$12.6 billion per annum, savings to public health budgets 15 across all health outcomes could be immense.