Does Green Space Benefit Health?
Research on Green Space
Research has found nature-based solutions can improve the health and well-being of urban residents through salutogenics; a study of the origins of health. Nature-based, or green space, has shown elements in the urban environment that facilitate psychological relaxation and stress relief, providing enhanced opportunities for physical activity and reducing exposure to noise, air pollution, and excessive heat. Many epidemiological studies have demonstrated various positive health effects of urban green spaces, including reduced depression and improved mental health, reduced cardiovascular morbidity and mortality, and reduced rates of obesity and diabetes. This research promotes the ideology between happy, healthy humans and the quality of greenness of the environment they live in. Urban green space is a nature-based solution, with a variety of known health and well-being benefits, that, if utilized, aid in the prevention of health issues.
Green Space Formulas for Health
The journey leading to beneficial health effects of green space is diverse and complex. Various research models try to explain the relationship between green space and health. One formula suggests these four interacting concepts; (1) improved air quality, (2) enhanced physical activity, (3) stress compensation, and (4) greater social cohesion. Another formula proposes; (1) physical activity, (2) engagement with nature, (3) relaxation, and (4) social interactions. Yet another formula argues that urban green spaces provide; (1) mitigation of the urban heat island effect by providing protection from heat-related health hazards, (2) improved social capital and cohesion, (3) and enhanced physical activity. In addition to the intentions outlined in these studies, another formula suggests exposure to natural microbes enhances immune system functioning as a major health and wellness benefit linking back to nature-based health solutions. Regardless of the formula used to measure the health benefit of green spaces on humans, the research results point to a positive effect from nature on a variety of health-related issues. Unfortunately, in order to persuade policymakers to require a percentage of acreage to be set aside in newly developed urban projects for green space establishment, more research and data are needed to narrow the knowledge gap concerning green space and how effective it is in preventing health issues and how therapeutic it is in treating existing ones.
Improved Relaxation and Restoration
The evidence of health benefits due to mental relaxation and restoration from contact with nature and green space is well documented. Research suggests that contact with nature, even visual only, triggers positive effects for persons with high-stress levels by shifting them to a more positive emotional state. These same stimuli in natural settings help to restore a sense of well-being in persons suffering from mental fatigue. One such study used wearable sensors to demonstrate a short walk in a green space enhanced relaxation and restoration of brain activity while also producing stronger short-term cognitive benefits. Another study showed that gardening alleviated acute stress faster than reading a book, based on the measured levels of Cortisol in the brain. Similar research demonstrates that exposure to green space reduces neural activity in the subgenual prefrontal cortex and alleviates depression symptoms. Recent studies have also provided evidence of chronic stress alleviation by green space. All of these studies point to a happier, healthier state of mind when green spaces are available for use.
Improved Immune System
Nature plays a fundamental role in enhanced immune functioning. It has been shown that visiting forests can increase immune system responses, including the expression of anti-cancer proteins. This suggests that immune systems benefit from exposure to natural environments or through contact with certain factors in green spaces. It has also been shown that children with the highest exposure to specific allergens or bacteria during their first year of life are less likely to have recurrent allergic sensitization. Living in residential areas with street trees is associated with lower asthma prevalence. Studies have demonstrated that increased biodiversity in the environment around homes results in a reduced risk of allergies. Greater exposure to commensal microorganisms, especially in children, may lead to more diverse skin and gut microbiomes, and provide protection against allergy and autoimmunity. These studies indicate a direct link between better immune system functioning, especially in children, from exposure to nature-based green space which can affect the quality of immune-related health issues throughout one’s life.
Enhanced Physical Activity and Fitness
Research on physical activity shows improvement in cardiovascular health, mental health, neurocognitive development, and general well-being and it also shows prevention of obesity, cancer, and osteoporosis. Providing attractive and accessible urban environments tends to encourage people to spend more time outdoors and encourages participation in physical activities. The quality of the urban green space and the presence of specific amenities are important factors facilitating physical activity in older adults. For urban residents with mental health problems, physical activity in green space may be particularly therapeutic. Numerous studies in multiple countries demonstrate that recreational walking, increased physical activity, and reduced sedentary time is associated with access to, and use of, green space in working-age adults, children, and senior citizens. Utilizing a satellite images data study, evidence of physical activity in green space, “green exercise”, is more abundant, at a higher level of physical activity, and regularly reproduced over physical activity in non-natural environments. The “green exercise” theory indicates that people are more likely to develop an exercise regimen and stick to it if green space is available to them. Providing appropriate design and equipment of green spaces, such as walkways, jogging trails, and fitness equipment; increases the likelihood of utilization of green space for physical activity benefits.
Enhanced Social Capital and Cohesion
Social relationships have a well-known positive effect on health and well-being, while social isolation is associated with morbidity and mortality. Green space can play an important role in fostering social interactions and promote a sense of community that is essential for social cohesion as well as human health and well-being. Public urban green space facilitates social networking and promotes social inclusion in children and adolescents. The quantity and the quality of available green space are directly linked with improved social cohesion at the neighborhood level while a shortage of green space is directly associated with perceptions of loneliness and lack of social support. However, the relationships between green space and social well-being are complex. Although observational studies demonstrate positive effects on well-being, understanding the underlying workings remains a challenge. Further research and studies will help determine specific characteristics associated with social networking and community cohesion around local green space availability. This information will help greatly in the design and development of future green spaces.
Restored Mental Health and Cognitive Function
Greater perceived neighborhood greenness is strongly associated with improved mental health in both males and females. Further analysis also demonstrates that this association is not mediated by physical activity. This suggests that psychological relaxation is an important contributing factor to health. It shows that individuals living in urban areas with more green space have reduced levels of depression, anxiety, and stress with overall better well-being compared to those living in areas with poorer availability of green space. Improved access to water bodies, blue spaces, also enhances mental well-being in urban areas. While most studies measured green space availability as a proxy measure of exposure, a multicity study in Europe linked the amount of time spent in green spaces with improved self-reported health and vitality. The effects were consistent in all four study sites in Spain, Lithuania, The Netherlands, and the United Kingdom suggesting that health benefits are independent of cultural and climatic contexts. Increased usage of green and blue spaces and greater residential greenness is also associated with improved behavioral development and a reduced rate of Attention Deficit Hyperactivity Disorder (ADHD) in children. Higher levels of greenness at home and school are associated with improved cognitive development in school children and a number of other studies have similarly demonstrated the positive impact of green space exposure on ADHD and related cognitive symptoms. There is even evidence of the therapeutic benefits of engaging people with autism to nature. All these studies collaborate the benefits of engaging in nature-based areas, especially for younger age groups.
Lower Potential of Obesity and Type 2 Diabetes
A summary of 60 studies from the United States, Canada, Australia, New Zealand, and Europe on the relationship between green space and obesity found that green space does help reduced obesity. A recent study in Spain confirmed these conclusions and showed living in greener residential areas and living in closer proximity to forests is linked with less sedentary time and reduced risks of overweight and obesity in children. Furthermore, there is some evidence that using green space for gardening influences physical activity, improves social well-being, and encourages eating healthy food, thereby reducing weight. A pilot intervention study for school-age children, using community gardening and education in nutrition as a basis, found that 17% of obese and overweight children improved their BMI classification by the end of the seven-week-long program. It is well-known that type 2 diabetes can be prevented by reducing obesity and improving physical activity. Cross-sectional observational studies in The Netherlands, Australia, and the United Kingdom demonstrate statistically significant associations between neighborhood greenness and reduced odds of having type 2 diabetes. By analyzing studies done around the world it is evident these findings are not related to geographical locations or cultures but consistent with all the human race and their need to have a physical connection to nature. Nature is a motivating catalyst that helps propel us into making better choices in regard to our physical health.
Increased Life Span
An analysis of previously conducted studies demonstrates that increased availability of green space is linked with a reduction of mortality. One study showed that the five-year survival rate in elderly individuals was positively associated with having access to green space suitable for taking a stroll and with parks and tree-lined streets near their residence. Another study of the population showed a greater amount of green space in neighborhoods was associated with reduced mortality from all elderly-related symptoms. This study also showed increased residential green space had a strong effect on reducing mortality from respiratory diseases in the elderly. Another study showed perceived greater neighborhood greenness being associated with reduced mortality risk during heat waves due to the urban heat island mitigating effects of green space. Residential proximity to green space is associated with a reduced risk of stroke mortality and shows a higher survival rate after having a stroke. Studies show access to green space reduces the detrimental impact of cardiovascular mortality while a greater distance to green space is associated with an increased risk of cardiovascular disease. A randomized intervention study demonstrated that walking in a park had a stronger effect on reducing blood pressure than a similar amount of walking along a busy urban street, suggesting this lifestyle could lead to a long-term clinical benefit. An observational study showed greater variability in the landscape, utilizing a combination of trees and open green space, is associated with a reduced risk of cardiovascular disease and stroke. The hypothesis for this variable in neighborhood greenness is thought to reflect two factors promoting physical activity – an aesthetically pleasing natural environment and access to urban destinations. It is important to note that each pathway providing access to green space can lead to more than one health benefit and that different pathways can also contribute to the same benefit. For example, cardiovascular benefits can be caused by enhanced physical activity, improved mental restoration leading to reduced chronic stress, and reduced exposure to air pollution and noise. Again, these studies, conducted in several countries, all show similar results and point to a need for well-designed, well-maintained, and strategically placed green space in urban areas for the maximum health benefits of all.
Available evidence suggests that access to urban green space leads to public health benefits in; (1) psychological relaxation and stress reduction, (2) improved immunity system, (3) enhanced physical activity and fitness, (4) enhanced social capital and cohesion, (5) restored mental health and cognitive function, (6) lower potential of obesity and type 2 diabetes, (7) and increased life span. Green space can also provide ecosystem services associated with reduced exposures to noise, air pollution, and excessive heat. The health benefits are consistent in all studies regardless of the physical activity exerted or in what country the studies were conducted. Noted negative green space effects are typically associated with poorly designed or poorly maintained areas, which can be easily reduced or prevented by proper planning, design, and maintenance. Measuring the availability, accessibility, and quality of green space, and monitoring green space usage are essential steps for providing needed information to support the requirements for green space health intervention. Overall, cities that build and maintain well-connected, attractive green spaces are likely to have healthier, happier, and more productive citizens with fewer demands placed on local health services.