A new study confirms that urban green spaces provide many health benefits, particularly from a cardiovascular perspective. The researchers conclude that there is a need to develop green spaces near where people live, and to expand them as soon as possible to better interact with nature.

Green spaces in cities linked to better heart health

Green spaces play a very important role in urban environments. Their presence appears to be associated with several significantly positive effects on the physical (physical activity) and mental (reduced symptoms of depression and stress) health of the population, including reduced exposure to pollution, noise and excessive heat.The Health Organization itself has stated that cities with attractive, well-connected green spaces are more likely to have a healthier population. Researchers at the University of Miami wanted to know if their multiple benefits also relate to a reduction in heart disease over time.

Their study presented at the European Society of Cardiology Congress (August 27-30) found that people who live in green neighborhoods are less likely to develop cardiovascular disease. "Higher levels of greenery were associated with lower rates of heart disease and stroke over time, both when an area maintained high greenery and when greenery increased," says lead study author William Aitken, M.D. "These relationships emerged over just 5 years, a relatively short time frame for a positive environmental impact."

As vegetation grows, do residents fare better?

The study included 243,558 Medicare beneficiaries aged 65 and older who lived in the same Miami neighborhood from 2011 to 2016. Their health records were used to obtain the 5-year incidence of cardiovascular disease: heart attack, atrial fibrillation, heart failure, hypertension, and stroke. Satellite images were used to assess the amount of visible and near-infrared (i.e., invisible) light reflected from the Earth's surface. "The chlorophyll in plants absorbs visible light and reflects near-infrared light, so measuring both indicates the amount of vegetation," the researchers note.

This system identified patches of green space and ranked them according to their importance while participants were also classified as living in patches of low, medium or high greenery in 2011. The process was repeated in 2016, a period of time during which the city conducted a tree planting program. "Thus, there was the possibility that a person living in a low-green patch in 2011 could be living in a high-green patch in 2016," the science team adds. The researchers then analyzed the risk of developing a new cardiovascular disease and the number of new cardiovascular conditions in these participants.

Social and economic benefits of green spaces

When comparing the heart health of people living in high-green areas to that of people living in low-green areas throughout the study, those in the former group had a 16% lower risk of developing new cardiovascular conditions. The researchers then compared the heart health of participants whose neighborhoods became greener over the years versus the heart health of participants who had always lived in low-green areas. Compared with the latter, residents living in areas that became greener between 2011 and 2016 had about a 15% lower risk of developing cardiovascular disease.

Finally, when the neighborhood became greener over time, residents developed 9% fewer new cardiovascular diseases, compared with residents whose green patch had not changed. According to the researchers, several factors may explain these observations. "For example, people living in greener areas may get more outdoor exercise and feel less stressed because of being surrounded by nature. In addition, vegetation does provide some protection from air and/or noise pollution," they say.

While further studies are needed to explore this finding in more detail, they already recommend that city planners and policy makers green cities as much as possible by planting trees as a low-cost investment to improve the health and well-being of a population. This would even relieve pressure on local health services and contribute to a stronger economy. "For the cost of a visit to the emergency room because of a heart attack, trees could be planted in a neighborhood of 100 residents and potentially prevent ten heart diseases in that group," the researchers conclude.