Green space is essential for good health but, in many cities, we don’t have enough of it or it is in the wrong place. We all enjoy a walk in the park, a street lined with trees or a view of trees from our window, but for those of us who are urban dwellers, we may not experience as much of this as we should.
Recently we analysed more than 1,000 cities in 31 European countries and found that up to 43,000 premature deaths could be prevented each year if these cities were to achieve the World Health Organisation (WHO) recommendations regarding residential proximity to green space. The data were published in The Lancet Planetary Health and the city ranking is available at isglobalranking.org.
The WHO recommends universal access to green space: there should be a green space measuring at least 0.5 hectares at a linear distance of no more than 300 metres from every home. Our results showed that 62% of the European population lives in areas with less green space than recommended.
Green space is associated with a large number of health benefits, including lower premature mortality, longer life expectancy, fewer mental health problems, less cardiovascular disease, better cognitive functioning in children and the elderly, and healthier babies. It also helps to mitigate air pollution, heat and noise levels, and provides opportunities for physical exercise and social interaction.
Particularly children, our future generation, appear to benefit from green space. For example, one study showed that children who went to a school with more green space had considerably better cognitive functioning than those who went to a school with less green space, while another study found that early childhood exposure to green space leads to fewer mental health problems in adult life.
Green space contributes to climate mitigation by reducing urban heat island effects, but it contributes relatively little to carbon sequestration, as cities account for only a small percentage of our land use and CO2 emissions are high. Green space can improve ecosystems and increase biodiversity in cities, particularly through well-designed green infrastructure throughout the city.
Too often green spaces are not close enough to where people live, so people don’t get the health benefits. The uneven distribution and health impact of green space is not only between cities, but also between different areas within the cities, which puts a significant proportion of citizens at a disadvantage, depending on which city or neighbourhood they live in. Poorer neighbourhoods in particular tend to have less green space and do not benefit from it.
European cities should focus on reclaiming urban land for green space, introducing nature-based solutions such as green roofs and vertical gardens, green school yards, green corridors, street trees, pocket parks, community gardens and other measures such as rerouting traffic, digging up asphalt and replacing it with green space, across the board. It is important that green spaces are accessible and close to residences.
Cecil Konijnendijk, an urban forester, recently proposed the 3-30-300 rule as a rule of thumb for green space in cities. He suggested that every citizen should be able to see at least three trees (of a decent size) from their home, there should be 30% tree canopy cover in every neighbourhood and no one should live more than 300 metres away from the nearest park or green space.
But the presence of green space may not be the only thing that matters: actual visits to nature are important for better health and well-being. Research suggests that two hours of visits per week is the minimum to maintain good health and well-being. Furthermore, the quality of green space —including biodiversity aspects such as the variety of tree species—is likely to be important, but so far has been less studied.
So why do cities still lack green space? Poor transfer of science to policy and practice, including cognitive bias, lack of and uncertainty in evidence, incommensurability between disciplines and sectors, vested interests and economic constraints are barriers to greening cities that we need to overcome. What is needed are leadership, skills, support, investment and some risk-taking to introduce more green space.
A number of large research projects are underway to address how we can overcome these obstacles. For example, the EU-funded GoGreenRoutes project is evaluating the implementation of nature-based solutions such as green corridors, linear parks, pocket parks and shared walkways to enhance physical and mental health in a large number of cities, and this will strengthen the evidence base. Importantly, the project will use co-creation to increase acceptance and effectiveness.
COVID-19 financial stimulus packages, such as the Biden administration’s infrastructure plan and the European Green Deal, can contribute a great deal financially to improve urban green space, particularly since parks provided great opportunities to mitigate mental health problems during the pandemic. Increasing urban green space should be a top priority for every city policy- and decision-maker.
There are too many ecological, environmental, climate, health and well-being benefits of green space to be ignored and we should urgently green our cities and bring green space closer to people. The barriers to greening may not be easy to overcome, but with a collective effort and the involvement of many and varied stakeholders (including you) it should be possible. Our green spaces are simply too precious.
Article originally published in ISGlobal Barcelona Institute for Global Health