live in a big city has many benefits and some drawbacks, the clearest being pollution and the stress of a life where the rush it is contagious without remedy. Take a break in an urban park or simply disconnect while looking at the trees from the window offers serious health benefits. According to science, urban green spaces promote longer life expectancy, better cognitive functioning and mood while reducing mental health problems. However, the exact amount of green space needed to improve people’s health remained unanswered.
better mental health
The study findings showed that full compliance with the 3-30-300 green space rule was clearly associated with a better mental health, less use of medications Y fewer visits to a psychologist, although the association was statistically significant only for the latter. Greenness of residential surroundings, but not window visibility of trees or access to significant green space, was significantly associated with better mental health.
The results indicate that only 4.7% of the population surveyed met the three criteria of the rule of green spaces. Just over 43% of respondents had at least three trees within 15 meters of their house, 62.1% had significant green space within 300 meters, and 8.7% lived in an area with sufficient surrounding vegetation. However, almost 22.4% did not have any of these elements.
Study in Barcelona
This cross-sectional study was based on a sample of 3,145 Barcelonans between the ages of 15 and 97 who participated in the Survey of Barcelona Health 2016 –carried out by the Barcelona Public Health Agency– and were randomly recruited. Mental health status was assessed with the 12-item General Health Questionnaire (GHQ-12). Eighteen percent of participants reported poor mental health, and 8.3% reported seeing a psychologist in the past year. In addition, 9.4% reported using tranquilizers or sedatives and 8.1% reported using antidepressants in the past two days.
“The study found that there are relatively few green spaces in Barcelona and that the 3-30-300 rule is fulfilled only for a small percentage of people, despite its beneficial effects on mental health,” he explained. Mark Nieuwenhuijsen Director of Urban Planning, ISGlobal Environment and Health Initiative and lead author of the study.
“There is an urgent need to provide citizens with more green spaces. We may need to remove asphalt and plant more trees, which would not only improve health, but also reduce heat island effects and contribute to carbon sequestration,” Nieuwenhuijsen noted. “Any initiative that leads to a greener city will be a step forward, the key message is that we need more and faster greening,” added the study’s lead author.
According to the research team, similar studies should be carried out in cities with more trees than Barcelona, since the lack of green spaces, especially sufficient grove, limits the ability to evaluate the 30% aspect of the 3-30-300 rule. “The question is to what extent a 30% tree canopy cover is feasible, especially in compact cities,” the researchers concluded.