But evidence-based research that can help us identify the healthiest environments to live is surprisingly scant. As scientists begin to tease apart the links between well-being and the environment, they are finding that many nuances contribute to and detract from the benefits offered by a certain environment – whether it be a metropolis of millions or a deserted beach.
“What we’re trying to do as a group of researchers around the world is not to promote these things willy-nilly, but to find pro and con evidence on how natural environments – and our increasing detachment from them – might be affecting health and well-being,” says Mathew White, an environmental psychologist at the University of Exeter Medical School.
White and other researchers are revealing that a seemingly countless number of factors determine how our surroundings influence us. These can include a person’s background and life circumstances, the quality and duration of exposure and the activities performed in it.
Generally speaking, evidence suggests that green spaces are good for those of us who live in urban areas. Those who reside near parks or trees tend to enjoy lower levels of ambient air pollution, reduced manmade noise pollution and more cooling effects (something that will become increasingly useful as the planet warms).
Time in nature has been linked to reduced physical markers of stress. When we are out for a stroll or just sitting beneath the trees, our heart rate and blood pressure both tend to go down. We also release more natural ‘killer cells’: lymphocytes that roam throughout the body, hunting down cancerous and virus-infected cells.
Researchers are still trying to determine why this is so, although they do have a number of hypotheses. “One predominate theory is that natural spaces act as a calming backdrop to the busy stimuli of the city,” says Amber Pearson, a health geographer at Michigan State University. “From an evolutionary perspective, we also associate natural things as key resources for survival, so we favour them.”
This does not necessarily mean that urban denizens should all move to the countryside, however.
City residents tend to suffer from more asthma, allergies and depression – but they also tend to be less obese, at a lower suicide risk and are less likely to get killed in an accident
City residents tend to suffer from higher levels of asthma, allergies and depression. But they also tend to be less obese, at a lower risk of suicide and are less likely to get killed in an accident. They lead happier lives as seniors and live longerin general. (Read more aboutfive of the world’s healthiest cities).
In other cases, rural pollution poses a major threat. In India, air pollution contributed to the deaths of 1.1 million citizens in 2015 – with rural residents rather than urban ones accounting for 75% of the victims. This is primarily because countryside dwellers are at greater risk of breathing air that is polluted by burning of agricultural fields, wood or cow dung (used for cooking fuel and heat).
Indonesia’s slash and burn-style land clearing likewise causes a blanket of toxic haze that lasts for months and sometimes affects neighbouring countries, including Singapore, Malaysia and Thailand. Meanwhile, smoke pollution from fires lit in South America and southern Africa has been known to make its way around the entire southern hemisphere. (That said, the air in the southern hemisphere is generally cleaner than in the northern hemisphere – simply because there are fewer people living there).
What about the idea of that pure mountain air? It’s true that black carbon aerosols and particulate matter pollution tends to be lower at higher altitudes. But trying to move above air pollution may cause other issues.
While people who live in in places 2,500m or higher seem to have lower mortality from cardiovascular disease, stroke and some types of cancers, data indicate that they also seem to be at an elevated risk of death from chronic pulmonary disease and from lower respiratory tract infections. This is likely at least in part because cars and other vehicles operate less efficiently at higher altitudes, emitting greater amounts of hydrocarbons and carbon monoxide – which is made even more harmful by the increased solar radiation in such places. Living at a moderate altitude of 1,500 to 2,500 meters, therefore, may be the healthiest choice.
There is a strong argument to be made for living near the sea – or at least near some body of water
On the other hand, there is a strong argument to be made for living near the sea – or at least near some body of water. Those in the UK who live closer to the ocean, for example, tend to have a better bill of health than those who live inland, taking into account their age and socioeconomic status. This is likely due to a variety of reasons, White says, including the fact that our evolution means we are attracted to the high levels of biodiversity found there (in the past, this would have been a helpful indicator of food sources) and that beaches offer opportunities for daily exercise and vitamin D.
Then there are the psychological benefits. A 2016 study Pearson and her colleagues conducted in Wellington, New Zealand found that residents with ocean views had lower levels of psychological distress. For every 10% increase in how much blue space people could see, the researchers found a one-third point reduction in the population’s average Kessler Psychological Distress Scale (used to predict anxiety and mood disorders), independent of socioeconomic status. Given that finding, Pearson says, “One might expect that a 20 to 30% increase in blue space visibility could shift someone from moderate distress into a lower category.” Pearson found similar results in a follow-up study conducted near the Great Lakes in the US (currently in review), as did White in an upcoming study of Hong Kong residents.
The team’s second analysis of nearly 200 recently redeveloped water sites will allow them to tease out how factors such as climate, weather, pollution levels, smells, seasonality, safety and security, accessibility and more, influence a given water body’s appeal. The ultimate goal, Bell says, is to find “what makes a great blue space.” Once the results are in, he and his colleagues will develop a quality assessment tool for those looking to most effectively restore urban canals, overgrown lakes, former docklands, rivers and other neglected blue spaces to make residents’ lives better.
“There might be a million other important things besides weather and daylight that influence someone in Hawaii versus Finland,” White says.
People who live in less regularly sunny places, like Vermont or Denmark, tend to have higher rates of skin cancer
In terms of health, data also suggest that, counterintuitively, people who live in more intermittently rather than regularly sunny places – Vermont and Minnesota in the US, for example, and Denmark and France – tend to have higher rates of skin cancer, likely because sunscreen is not part of daily routines. (Read more aboutfive countries where people live the longest).
Just as some green and blue spaces may be more beneficial than others, researchers are also coming to realize that the environment’s influence on well-being is not evenly distributed.
People living in lower socioeconomic conditions tend to derive more benefits from natural spaces than wealthy residents, White says. That’s likely because richer people enjoy other health-improving privileges, such as taking holidays and leading generally less stressful lives – a finding with important real-world implications. “Here in the UK, local authorities have a legal obligation to reduce health inequalities. So one way to do that is to improve the park system,” White says. “The poorest will benefit the most.”
Bell adds that proximity to nature actually tends to rank low on people’s lists of the most important factors for selecting a place to live, after things like safety, quietness and closeness to key locations like schools and work. But while the benefits of green and blue spaces should not be overplayed on an individual level, they are important for the scale at which they work.
And even so, one takeaway seems obvious: those living in a clean, oceanside city with ready access to nature – think Sydney or Wellington – may have struck the jackpot in terms of the healthiest places to live.
By Rachel Nuwer 1 June 2018