Heres's a really interesting recent piece of research, asking what kinds of benefit to health accrue form what kinds of 'dose'? It's a vital question, especially if we are to move towards proper commissioning of the health and wellbeing services provided by ecosystems, because economics is always the most likely stumbling block.
The research is published in Nature's Scientific Reports and is available here. One of the authors is based in Cornwall, Kevin Gaston at the University of Exeter's Environment and Sustainability Institute.
Here's part of what the authors summarises about dosage:
"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".
That's the key - the immensity of the potential gain. We're using evidence like this to develop the case in Cornwall for a systematic and widely available nature-on-referral service at the moment. If you're really keen to explore this topic, theres' a kind of sister paper that summarises the value and thinking behind dose-response analysis when it comes to nature, available here.