The health benefits of urban green spaces are numerous and well known, such as increased life expectancy, reduced mental illness, and improved cognitive function. However, the answer to the problem of the exact surface area of green spaces required to promote the health of populations remains open.
What does the 3-30-300 rule 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. In accordance with this general rule, everyone must be able to see at least three trees from their home, have 30% tree cover 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 linked to improved mental health, reduced medication use, and fewer consultations in a psychologist, even if this relationship is only statistically significant.
Findings from this survey indicate that only 4.7% of those taking the survey meet all three aspects of the green space rule. Thus, just over 43% of respondents had at least three trees within a radius of 15 meters around their home, 62.1% had a significant green space within a radius of 300 meters, and 8.7 % of respondents lived in a relatively green area. On the other hand, almost 22.4% did not benefit from all these conditions.
3 trees for each household.
The first rule states that everyone must be able to spot at least three trees from their home. Recent research demonstrates the importance of a nearby, and especially visible, green environment for mental health and well-being. During the COVID-19 pandemic, people have often been confined to their homes or their direct neighbourhoods, giving even greater importance to nearby trees and other green spaces, in gardens and along streets. .
30% tree cover in each neighborhood.
Studies have shown an association between urban forest cover and, for example, cooling, better microclimates, mental and physical health, and possibly also reduced air pollution and noise. Many of the world’s most ambitious greening cities, including Barcelona, Bristol, Canberra, Seattle and Vancouver, have set targets to achieve 30% green cover. At the neighborhood scale, 30% should be a minimum, with cities striving to achieve even higher canopy coverage where possible. Where it is difficult for trees to grow and thrive, for example in arid climates, the goal should be 30% vegetation.
300 meters distance between the place of residence and the nearest green spaces.
Numerous studies have highlighted the importance of proximity and easy access to quality green spaces that can be used for recreational purposes. A safe 5 minute walk or a 10 minute walk is often mentioned. The European Regional Office of the World Health Organization recommends respecting a maximum distance of 300 meters separating the nearest green space (of at least 1 hectare).
This encourages the use of green spaces for recreational purposes, which has positive repercussions in terms of physical and mental health. Of course, it will be important to work with the local context, as the needs in low-density suburban areas, for example, will be different from those in denser urban areas. But here too, efforts must 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 walking paths. Applying the 3-30-300 rule will improve and expand the local urban forest in many cities and thereby promote health, well-being and resilience.