The largest ever study to look at urban green spaces has outlined how green areas can impact mortality.
According to a systematic review and meta-analysis conducted by the Barcelona Institute for Global Health (ISGlobal), in collaboration with Colorado State University and the World Health Organization (WHO), has emphasised how urban green spaces can protect against premature all-cause mortality.
The analysis, published in The Lancet Planetary Health, which included nine longitudinal studies involving seven countries – Canada, United States, Spain, Italy, Australia, Switzerland and China – and a total of over eight million people, provides strong evidence on the impact of increasing green areas on mortality.
Urban green spaces reduce mortality
Half of the world’s population lives in cities, where there is often a lack of green space.
Many studies suggest that green spaces in cities have a positive health effect, including less stress, improved mental health, and lower risk of cardiovascular disease, metabolic syndrome and premature death, among others.
However, many of these studies look at only one specific point in time and use different ways to measure exposure to greenness.The research team decided to summarise the available evidence and focus on studies that were longitudinal studies following the same cohort of individuals during several years. They used a simple measure of exposure to green space – the Normalised Difference Vegetation Index (NDVI) based on satellite images.
The meta-analysis of these studies found that an increment in greenness around homes is significantly associated with reduced premature mortality. More specifically, the study provides an estimate for the protective effect: a 4% reduction in premature mortality per each increment of 0.1 in vegetation score, within 500 meters of the residence.
David Rojas, researcher at ISGlobal and Colorado State University and first author of the study, said: “This is the largest and most comprehensive synthesis to date on green space and premature mortality and the results support interventions and policies to increase green spaces as a strategy to improve public health”.
Rojas and colleagues are currently applying the results of the above meta-analysis to estimate the number of premature deaths that could be prevented in cities around the world if the city achieved its ambitious goal of increasing green infrastructures.
“Urban greening programmes are not only key to promoting public health, but they also increase biodiversity and mitigate the impacts of climate change, making our cities more sustainable and livable” concludes Mark Nieuwenhuijsen, director of the Urban Planning, Environment and Health Initiative at ISGlobal.
