‘Nature lessens anxiety and slows cognitive decline’

Peter James teaches environmental

health

at

Harvard

University's TH Chan School of Public Health. Speaking to Times Evoke, he discusses why nature equity matters:



I research how green spaces affect our health and well-being as well as equity in such nature access across racial and socioeconomic lines. Access to nature is a core element of many of our health outcomes and my work quantifies this. We use data from large-perspective cohort studies like the

Nurses

’ Health

Study

started in 1976. We’ve followed hundreds of thousands of individuals over decades. We study mortality and disease information and with participants’ addresses, link these to spatial data like satellite information showing nature.



We can then see how nature exposure is linked to several health outcomes. A growing amount of data now shows people who live in green spaces have better cognition and a slower rate of cognitive decline. This is consistent with the attention restoration theory which posits that we have evolved with nature and being within it is our natural setting. Modern society requires us to have directive attention, where we are focused on, say, a computer or a phone screen but nature allows us to replenish our attention and get ready for the next cognitive task. This could underlie why, when we are typing intensely on a computer, for instance, we look out of a window often and only then get back to it.



Nature boosts our attention. The stress recovery theory also finds that looking at nature’s scenes helps us recover from stresses quicker — evolutionarily, this allows us to be ready for the next survival task. People with more exposure to green spaces therefore perform better on biomarkers of stress and objective tests. They also have lower depression — we’ve found teenagers growing up in greener spaces experience lower

anxiety

levels.



In a study in Denmark , researchers looked at the psychological records of the entire population — people who grew up or lived in areas that were greener had lower incidents of every psychiatric outcome on the record fourty years later. This is an absolutely remarkable finding for mental health. We use many ways to measure these links. One method is GPS devices like smartphone apps to understand participant access to nature.

We use accelerometery or consumer wearables which give us granular, minute-level data of whether people become more vigorous in green spaces than built-up ones. We’re also using Google Street View data, processed through deep learning algorithms, to understand the percentage of trees or how much grass or bushes there are in a location. We can then say with specificity what seems to be the active ingredient in nature that helps participants the most, from trees to parks to sitting on the grass. But access to green spaces is inequitable — it’s easier for rich people and much harder for the poor to experience these. This exacerbates multidimensional health inequality. Access to nature should be treated as an essential factor for us to function. It should be considered crucial enough to be envisioned and planned for in our budgets. Importantly, ‘nature’ isn’t only an awe-inspiring reserve like Yosemite or travelling on safari. It is as simple as a tree standing by your home. A tree was planted by my house when my first child was born — I’ve watched it grow over the last three years. Everyone should be lucky enough to have access to everyday nature. A very appealing concept termed ‘3-30-300’ posits that every home should have a view of three trees, every neighbourhood should have thirty percent canopy cover and three hundred metres distance to the nearest green space. Humans are a part of nature. We need the profound benefits it gives us — and we need these equitably.

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