The health benefits of urban green spaces, such as increased life expectancy, reduced mental illness and improved cognitive function, are numerous and well known. However, the answer to the question of the exact area of green spaces needed to improve people’s health remains open.
What does Rule 3-30-300 mean?
Recent research conducted by ISGlobal, an organization supported by the “la Caixa” Foundation, examined the relationship between better mental health and the 3-30-300 principle of green spaces. According to this general rule, everyone must see at least three trees from their home, 30% of the trees must be in their neighborhood and live no more than 300 meters from the nearest park or green space.
Findings from this survey reveal that full compliance with the 3-30-300 Green Space Rule is significantly associated with improved mental health, reduced medication use, and fewer consultations with a psychologist, although this relationship is not statistically significant.
Findings from this study show that only 4.7% of survey respondents meet all three aspects of the green space rule. Thus, more than 43% of the respondents had at least three trees within a radius of 15 meters around their house, 62.1% had a significant green space within a radius of 300 meters, and 8.7% of the respondents lived in a relatively green area. On the other hand, nearly 22.4% did not benefit from all these conditions.
3 trees for every household.
The first rule states that everyone must find at least three trees from their home. Recent research demonstrates the importance of nearby and especially visible green environments for mental health and well-being. During the COVID-19 pandemic, people are mostly confined to their homes or their immediate surroundings, placing even greater emphasis on nearby trees and other green spaces, gardens and streets.
30% trees are covered in each neighborhood.
Studies show a connection between urban forests, for example, cooler, better microclimates, mental and physical health, and can reduce air pollution and noise. The world’s most ambitious green cities, including Barcelona, Bristol, Canberra, Seattle and Vancouver, have set targets to achieve 30% green. At the neighborhood level, 30% should be the minimum, with cities trying to achieve even higher canopy coverage as possible. In areas where trees are difficult to grow and thrive, for example in dry climates, the target should be 30% vegetation.
300 meters distance between residence and nearest green spaces.
Several studies highlight the importance of proximity and easy access to quality green spaces that can be used for recreational purposes. A safe 5-minute walk or 10-minute walk is often recommended. The European Regional Office of the World Health Organization recommends respecting a maximum distance of 300 meters separating adjacent green space (at least 1 hectare).
It encourages the use of green spaces for recreational purposes, which has positive effects in terms of physical and mental health. Of course, it is important to work with the local context, as the needs in low-density suburban areas, for example, will be different from those in dense urban areas. But here too, efforts should be made to provide access to quality urban green spaces, for example in the form of linear green spaces that act as cycle paths and sidewalks. Applying the 3-30-300 rule will improve and expand local urban forests in many cities, thereby improving health, well-being and resilience.