Body and Mind

Greener cities could help you to live longer

Greener cities could help you to live longer
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As the global population steadily increases it becomes significantly more likely that at some point most of us will end up living in a busy, urban area. Often grey and a bit gloomy, cities can feel close and claustrophobic leaving you craving fresh air under a green canopy. It always feels good to get out of the city but the benefit of green spaces might go beyond placebo.

By 2030, urban areas could provide a home for 60% of the world’s population with one in three people living in a city housing over half a million inhabitants, according to the United Nations. An increase in population density means that green spaces are often sacrificed to build more homes making cityscapes even more uninviting and widening the gulf between rural and urban living.

It might not just be aesthetics that suffer when green spaces are removed. In seeking a solution to pollution smog and rising temperatures, scientists are increasingly finding that plants and trees could provide answers to the problem of creating more sustainable cities. Urban living of the future could see us attempting to regreen environments by using unconventional means like green walls and roof gardens. Instead of treating the rural and urban as vastly different environments, our relationship with where we live needs to change to blur these artificial boundaries.

It’s no secret that walking in the fresh air surrounded by greenery certainly makes us feel better but there is also scientific evidence that it is measurable good for our physical health. Research from the University of East Anglia found that having access to green spaces can reduce your risk of type II diabetes, cardiovascular disease, premature death, preterm birth, stress and high blood pressure. This is pretty significant for global health as more than one of these illnesses can be found on the World Health Organisation’s top 10 causes of death.

Read More | Is the Science driving tree planting trends 'dangerously misleading'?

The link between green spaces and life expectancy

So, how much greener do our cities need to be to benefit our health? After taking a look at 9 major studies, Lancet Planetary Health found that just a small increase in the green spaces that surround your home could have an impact on your life expectancy. Across 7 countries, researchers collated information from 8.3 million people and found that a 10% increase in greenery led to a 4% decrease in early death on average.

The greenness of areas was measured using something called the “vegetation index”. On this scale, an arid desert would score 0 whilst a lush tropical rainforest would be 1; increasing this index by just 0.1 improves early death rates for people who live within 500m. Although the study doesn't explicitly look at why more tree might make you live longer, but the possibility that surrounding yourself with greenery could add years to your life is compelling.

In summer of this year the Mayor of Paris, Anne Hidalgo, announced a tree planting scheme to create an “urban forest”. At four iconic sites, the city will be creating “islands of freshness” intended to counter the bubble of heat generated by its inhabitants that encloses most urban environments. The city hall is planning to have 50 per cent of Paris covered by planted areas by 2030, a goal that will require every free centimetre to be utilized from verges to squares to roofs.

The UK government have also committed to regreening cities across the country. A £10 million plan with see 130,000 trees planted in towns and cities from London to Aberdeen. Then Environment Secretary, Michael Gove, called trees “vital in the fight against climate change” as he launched the £10m fund. Helen Griffiths, Chief Executive of Fields in Trust, told euronews Living "Our research found that parks and green spaces generate £34.2 billion worth of physical and mental health benefits each year. It’s a persuasive statistic, as is the fact that £111 million worth of NHS savings are made annually in reduced GP visits alone, because frequent park users have better general health and are less likely to visit their doctor."

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Atlanta's trees: A cautionary tale

Although tree planting may not necessarily be the solution to all of the planet’s pollution problems, in cities it has a direct positive effect on health and also on environmental factors that might impact it. Other studies highlighted by The Lancet paper show that trees, in particular, are great at reducing air pollutants as well as reducing the effects of noise and heat from heavy city traffic.

Once known as a "city in a forest", Atlanta in the United States provides a good case study for the effects of regreening. Between 1973 and 1999, over 225,000 hectares of trees were cleared to build shopping centres, roads, and rows upon rows of cookie cutter housing. Losing this dense tree cover led to a third more water running off the streets and into drains during storms, increasing the chances of damaging floods and making costly preventative measures necessary.

The decline in tree cover in Atlanta has had a serious impact on the cityAmerican Forests Report

Tree cover also reduces temperatures as shade keeps the sun off of the highly reflective materials that make up urban buildings. In stopping cities from becoming "urban heat islands", or areas where the air temperature is 1 to 4 degrees celsius higher than in surrounding rural areas, the study of Atlanta found that trees reduced summer energy usage. By reducing the amount of air cooling needed by the residents of Atlanta, the area's energy use would be slashed and emissions cut by nearly 600,000 tonnes of CO2. That's the same as taking 127,389 cars off the streets for a whole year.

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