Mental health problems are a major cause of disease and disability worldwide. Currently, mental and addictive disorders contribute to 7% of all Disability-Adjusted Life Years (DALYs) of global burden of disease and 19% of all years lived with disability. There is therefore an emerging need for interventions to protect and promote mental health. A growing body of research shows that green spaces could play an important role in this, as exposure to nature has been shown to provide significant benefits for mental health.
A growing body of research shows that green spaces could play an important role in protecting and promoting mental health
Green spaces are open spaces partially or completely covered by natural elements (i.e. vegetation) and include urban parks, forests, gardens, and trees along the street. These environments provide daily contact with nature when present in the residential neighbourhood, near workplaces, or on commuting-routes between these and to other destinations. Urban green spaces are increasingly important as due to the rapid, worldwide urbanization, a growing number of people live in cities. Already over half of the world population lives in urban areas, and in Spain, this is already around 80% of the population. These urban areas often provide predominantly built environments where exposure to nature is scarce.
Exposure to nature may be indispensable for human wellbeing. Humans are suggested to have an intrinsic urge to connect with nature and other forms of life. Contact with nature may help reduce feelings of stress, restore the ability to concentrate and pay attention, and improve the emotional state. Indeed, experimental studies have observed that study participants had an improved mood, more self-esteem, and a lower level of stress when they were exposed to natural environments. Regarding longitudinal exposure, epidemiological studies observed that an increased long-term exposure to green spaces is associated with improved mental health. In these studies, long-term exposure to green space was assessed as, for instance, the amount of vegetation surrounding the home, the percentage of land in the residential neighbourhood dedicated to green space, or the distance from the home to the nearest green space. These exposures were associated with improved mental health outcomes in numerous observational studies, including large, population-based studies and longitudinal studies.
How green spaces can be linked to mental health
An increased availability of and access to green space could promote mental health by providing a calm, restorative, and serene refuge. Even by just visual access (i.e. viewing natural scenes), green space exposure could reduce stress and restore the ability to pay attention and concentrate. Moreover, green spaces provide a place for physical activity and social interactions with neighbours. In addition, exposure green space has been associated with a reduced exposure to other environmental stressors such as air pollution and noise, which could harm mental health.
Even by just visual access (i.e. viewing natural scenes), green space exposure could reduce stress and restore the ability to pay attention and concentrate
For instance, a recent study of ISGlobal found a protective association between the amount and access to green space and anxiety and depression. This association was observed to be partially explained by a reduced exposure to air pollution and noise and, to a lesser extent, by increased physical activity and social support.
Green spaces and children
Exposure to green spaces has been suggested to be especially beneficial for children. Over the last decades, there has been a large change in where children grow up and where they play; nowadays, most children grow up in neighbourhoods with little greenspace and, moreover, spend most of their time inside. In contrast, spending time in greenspace provides opportunities for “unorganized play”; natural elements can stimulate the urge to explore the surroundings, not only discovering other forms of life (insects, plants, trees, etc) but also own abilities to run, climb, and use their imagination. As such, contact with nature could be extremely beneficial for child development and mental health.
Natural elements can stimulate the urge to explore the surroundings, not only discovering other forms of life (insects, plants, trees, etc) but also own abilities to run, climb, and use their imagination
An increasing number of epidemiological studies have confirmed this beneficial association between exposure to green space and mental health in children and adolescents; a recent systematic review of 21 studies reported that most studies observed a beneficial association between green space exposure and mental health in children, adolescents, and young adults, including outcomes of emotional and behavioural difficulties, mental well-being, and neurocognitive development. The review found the strongest associations between increased green space exposure and decreased hyperactivity and inattention problems in children.
Green spaces and older adults
Also for older adults, green spaces could have an important beneficial impact on mental health. Older adults in general spend more time in their direct neighbourhood environment than younger generations due to, for instance, retirement or reduced mobility. Green spaces in the neighbourhood provide incentive for daily walks and opportunities for interactions with neighbours, which help older adults to stay physically and socially active, which in turn benefits mental health.
An increasing number of studies has investigated the association between long-term green space exposure and outcomes of mental health (including stress, depression, and anxiety) in middle aged and older adults. Most of these studies showed a significant, protective association. One of the works with the strongest study design observed a 13% reduction in risk of depression among older women (54-91 years) who lived in the highest quintile of residential green space compared to those living in the lowest over a follow-up of 10 years.5
One of the works with the strongest study design observed a 13% reduction in risk of depression among older women (54-91 years) who lived in the highest quintile of residential green space
These results are especially relevant considering the rapid growth in the older population adults and the increasing number of older adults living in mainly urban environments, where they may be more vulnerable to exposure to air pollution, heat, and noise and social isolation than younger age groups.
Over the last decades, there has been a large change in the places where we live and work. In previous generations, many people depended on agriculture and lived in rural areas. Nowadays, most people live in cities and spend most of their days inside in their homes, offices, schools, etc. Our daily contact with nature now largely depends on access to green spaces. A growing evidence base of research shows that increased exposure to these environments is associated with improved mental health. Therefore, green spaces have important contributions to healthy urban living and should be considered a significant resource for public health.