MIAMI — Apparently, Green Acres really is the place to be. New research reveals that people who live in tree-lined neighborhoods with an abundance of “greens” are less likely to suffer a heart attack or a stroke.
Making urban areas greener has many benefits, but researchers wanted to know whether it had any relationship with rates of heart disease. The team also examined whether planting more vegetation in a locality would be accompanied by reductions in heart disease over time.
The study includes data from more than 243,000 Americans aged 65 or older who lived in the same area of Miami from 2011 to 2016. Medical records were used to obtain the incidence of new cardiovascular conditions during the five-year study, including heart attacks, irregular heartbeat, heart failure, heart disease, high blood pressure, and strokes.
Satellite images were used to analyze the amount of sunlight reflected from the Earth’s surface. The researchers said that chlorophyll from plants typically absorbs visible light and reflects near-infrared light, so measuring both indicates the amount of vegetation. The “greenness” of city blocks was then classified as low, medium, or high.
“Higher levels of greenness were associated with lower rates of heart conditions and stroke over time, both when an area maintained high greenness and when greenness increased. It was remarkable that these relationships appeared in just five years, a relatively short amount of time for a positive environmental impact,” says study author Dr. William Aitken of the University of Miami in a statement.
Heart health for residents in high-greenness neighborhoods versus those in low-greenness blocks
The participants were categorized based on whether they lived in low, medium, or high-greenness blocks in 2011. The process was repeated for those same residents and the greenness of their blocks in 2016. There was the possibility that someone in a low-greenness block in 2011 could be living in a high greenness block by 2016 due to the tree planting program of Miami-Dade County Parks and Recreation during the study period.
Researchers analyzed the residents’ odds of developing any new heart disease events and the number of new cardiovascular conditions based on block-level greenness. The analysis was adjusted for other factors that could be related to heart disease including age, sex, and race.
The researchers first compared heart health among those continually living in highly green neighborhoods compared to low-greenness areas during the five-year study. Residents of high-greenness blocks throughout the study had a 16 percent lower odds of developing any new cardiovascular conditions compared to those in low-greenness blocks. Among participants who developed a cardiovascular condition during the study period, those in high-greenness areas developed four percent fewer new diseases compared with those in low greenness blocks.
The researchers then compared heart health in participants whose neighborhood became greener to those who continued to live in areas with low vegetation. When compared to residents of low-greenness areas throughout the study, those living in areas that increased their greenness from low in 2011 to high in 2016 had 15 percent lower odds of developing new cardiovascular conditions. Among participants who developed a cardiovascular condition during the study, those whose neighborhoods became greener developed nine percent fewer new cardiovascular conditions compared to residents of localities with continually low levels of greenness throughout the study.
“We suspect that multiple factors may account for these observations. For instance, people living in greener areas may do more outdoor exercise and might feel less stressed due to being surrounded by nature. In addition, vegetation could provide some protection from air and/or noise pollution. This is an area for further exploration,” says Dr. Aitken. “Tree planting and greening of neighborhoods is associated with multiple benefits and offers a relatively low-cost investment to enhance health and well-being in many circumstances. For the cost of one emergency room visit for a heart attack, trees could be planted in a neighborhood with 100 residents and potentially prevent ten heart diseases in this group.”
The findings were presented at the European Society of Cardiology Congress.
South West News Service writer Stephen Beech contributed to this report.