In 2016, a study from the Harvard T.H. Chan School of Public Health concluded that women who lived in homes surrounded by more vegetation had a lower mortality rate than those who lived in areas with less .
The study, which was conducted over an eight-year period, found that women who lived in the greenest surroundings had a mortality rate that was twelve percent lower than women who lived in the least green areas.
Since then, more and more research has gone into determining the link between nature and health, and so far the results are unanimous: the more exposure we have to nature, the healthier we are.
The Data is In
Nature exposure has been linked to a variety of health benefits, but the mechanism behind them is still not well understood. The researchers involved in this 2016 study determined four reasons why “greenness” might lead to a lower mortality rate:
- Improved mental health: for the purposes of the study, mental health was measured through a reduction in depression, which was estimated to account for nearly thirty percent of the benefits of living in areas with more vegetation.
- Increased opportunities for social engagement.
- Greater levels of physical activity.
- Reduced exposure to air pollution.
The association between lower mortality rates and exposure to nature was so strong it even surprised the researchers themselves.
“We were even more surprised to find evidence that a large proportion of the apparent benefit from high levels of vegetation seems to be connected with improved mental health,” said Peter James, a research associate in the Harvard Chan School Department of Epidemiology .
Out of the 108 630 women who were enrolled across the study, the researchers found that the higher amounts of greenness and lower mortality rates were the strongest for respiratory disease and cancer- women living in greener areas had a 34 percent lower rate of respiratory disease-related mortality and a thirteen percent lower rate of cancer-related mortality .
The environmental benefit of having more trees and plants in urban and suburban settings are well understood, but these findings suggested that improved health is a co-benefit to improving the environment.
Nature and Health
There is a wealth of evidence pointing toward the benefits of nature and health.
Children with attention deficit disorder have demonstrated improved concentration after a walk in the park , cancer patients who visited a forest showed increased activity and expression of anti-cancer proteins , “forest bathing” has been shown to reduce hypertension in the elderly , and even simply looking out a window at nature has been shown to improve recovery time for patients who have undergone surgery .
The Research Continued
In 2018, a group of researchers decided to take a deeper dive into understanding how nature has such a profoundly positive impact on humans. They conducted two separate studies, and came to some interesting conclusions.
First, they found that exposure to nature has a restorative effect on humans, and there are two theories to explain this impact: The Stress Reduction Theory (SRT) and the Attention Restoration Theory (ART) .
SRT suggests that exposure to natural environments facilitates positive emotional reactions, which in turn have a restorative effect.
ART suggests that nature exposure encourages effortless brain function, which helps the brain recover from fatigue.
2. Social Cohesion
Another explanation is that the social consequences of natural settings are the underlying mechanism to the health and wellbeing effects of nature. The evidence suggests that nature increases social cohesion within a community. Social cohesion refers to a sense of community, shared norms and values, positive and friendly relationships, and feelings of being accepted and belonging.
Additionally, exposure to nature appears to enhance social connections, and reduces feelings of loneliness and inadequate social support, which leads to an overall improvement in self-reported health.
3. Physical Activity
Having more natural space, particularly in urban settings, appears to encourage physical activity. Evidence has shown that “green physical activity”, or rather, physical activity while in direct contact with nature, improves health and well-being.
4. Impulsive Decision-Making
Impulsive decision making, or delay discounting, has been associated with chronic illness and premature death in the United States. This is because impulsive decision making is strongly implicated with a lack of exercise, poor diet, tobacco use, and excessive alcohol consumption.
Essentially, it is common for adults to choose whatever provides immediate gratification regardless of the long term effects. It appears that exposure to nature actually reduces the instance of impulsive decision-making, therefore leading to improvements in overall health .
The Five Categories of Health
This research falls in line with the US Department of Agriculture’s publication called Urban Nature for Human Health and Wellbeing, in which the authors outline the five general categories of health:
- Pollution and Physical Health
- Active Living
- Mental Health
- Stress Reduction
- Social Health, Cohesion, and Resilience .
The association between nature, pollution, and physical health comes down to two major factors: air quality, and urban heat.
Excess air pollution can lead to airway inflammation and reduced lung function, and worsen health problems like asthma, chronic obstructive pulmonary disease, and cardiovascular disease. Trees and vegetation in parks can reduce air pollution by directly removing air pollutants.
The cooling effects of green spaces in urban areas are directly quantifiable. Because cities are built primarily out of materials like concrete, metal, and asphalt that absorb significant amounts of heat, they tend to be much hotter than agricultural or forested areas. This heat has a direct impact on human health, and causes heat-related deaths, illnesses, and hospitalizations.
Greenspaces within cities, as well as vegetation planted throughout, have been shown to decrease the temperature leading to fewer heat-related deaths .
As previously outlined, greater exposure to nature has been demonstrated to impact the remaining four categories of health- active living, mental health, stress reduction, and social health.
It is important to remember that none of these categories operate independently of one another. Active living has been shown to improve mental health, as has stress reduction and social cohesion, and improving one category will improve them all.
How Much Nature Do We Need?
There is no ceiling in terms of how much exposure to nature is enough, however there has been some research done to determine the minimum requirements in order to experience health benefits.
A 2019 study published in Nature determined that at least 120 minutes (two hours) per week in nature was associated with improved health and wellbeing. The researchers determined that it did not matter how this time was split up (one two-hour session once per week or several shorter ones), as long as the minimum time requirement was met .
If you live in a dense urban center and you have difficulty getting out into nature as much as you like, consider keeping some plants inside your home or apartment. Indoor plants help you feel like you’re in a more natural setting, and while it’s not a replacement for getting outside to a park or trail, it still does provide some benefits.
So whether you take a stroll through the park, a walk through the forest, or simply find a peaceful spot by a stream to sit and relax, the research all points to the same conclusion: nature is good for your health.