Barcelona green space plan could improve health of 30,000, study finds

An ambitious push to create more green spaces in Barcelona – a city with one of the highest population and traffic densities in Europe – could improve the health of more than 30,000 people, reduce the use of antidepressants and save up to €45m (£40m) annually in costs associated with mental health issues, research suggests.

It builds on a growing body of evidence that has linked urban green spaces to better mental wellbeing as well as the prevention of depression, anxiety and insomnia.

“Green space is a huge and underutilised ally,” said Carolyn Daher of the Barcelona Institute for Global Health and one of the authors of the study, published this week. “We need to be much more invested in preventing illness and creating health and wellbeing at the source. And that’s where the urban model comes into play.”

The starting point for the research was a plan, launched by Barcelona officials in the Eixample district in 2020, to swap out car-clogged intersections for plant-filled spaces that prioritise pedestrians and cyclists. Known as Green Axes, or Eixos Verds in Catalan, the plan ultimately envisions turning one out of every three streets across the city into a green zone.

Researchers calculated that the plan, if fully implemented, could boost green space across the city by 5.7%. Using a framework established by previous studies that linked green spaces to mental health, they crunched the numbers on the potential impact of the Barcelona plan.

“What we found was that – even though we’re only increasing the green [space] by about 5 or 6% – you get quite a considerable reduction in the number of cases of mental health problems,” said Mark Nieuwenhuijsen, a co-author of the paper, also with the Barcelona institute.

Their modelling estimated that the surge in vegetation could prevent as many as 31,000 cases of “poor mental health”, decrease the number of visits to mental health specialists by 13% and reduce the use of tranquillisers and sedatives by 8% annually. The result could translate to savings of as much as €45m a year in direct and indirect mental health costs.

The estimates came with caveats: the green interventions need to be evenly distributed across the city and accompanied by policies that foster high-quality public transport systems and low-emissions zones as well as strategies to prevent speculation and gentrification.

While the findings offer a potent argument for increasing green space in a city where just 20% of the population meet the WHO’s recommendation for access to green space and where air pollution remains chronically high, not everyone is seemingly onboard, according to Nieuwenhuijsen.

“Unfortunately what we see at the moment is going the other way,” he said, pointing to recent reports of plans by regional authorities in Catalonia to cut down more than 100 trees in one of the city’s central parks in order to make way for a train station.

As municipal officials seek to trade traffic jams for tree-lined plazas, the reduction in traffic had become a polarising issue ahead of municipal elections in May, said Daher. “We need to show people the benefits of this because there’s been a lot of pushback,” she said.

The research had implications for cities beyond Barcelona, she said, particularly after the Covid pandemic laid bare the limits of healthcare systems around the world.

“I think a lot of people don’t understand that the urban environment that we live in is a public health intervention and a very important one,” she said. “It’s a very powerful way to create health from the beginning, so that less people get sick.”