Increasing vegetation in urban areas can reduce all-cause mortality, the study reveals

A new analysis of vegetation and mortality found that between 34,000 and 38,000 deaths could have been reduced by local increases in green vegetation in U.S. metropolitan areas.

Growing vegetation in U.S. urban areas can substantially reduce all-cause mortality, according to a new study led by researchers at Boston University School of Public Health.

Published in the journal Frontiers in Public Health, the national study found that growing green vegetation in large metropolitan areas could have prevented between 34,000 and 38,000 deaths, according to 2000-2019 data. The study also showed that general green in metropolitan areas has increased in the last 20 years, by almost 3% between 2000-2010 and 11% between 2010-2019.

The study is based on well-established research on the health benefits of greenery, providing quantitative value to the potential impact of urban greening initiatives on mortality.

“We know that living in greener areas can have a positive impact on our physical and mental health, but there is a lack of data on how changes in the distribution of greenery can affect mortality rates across the country.” says the study’s lead author, Paige Brochu. , PhD student in the Department of Environmental Health. “Our study quantifies the impact of the expansion of greenery in urban areas and shows how increasing green vegetation could increase a person’s life expectancy. Policy makers and urban planners can use this information to support local climate action plans and ensure that such plans include greening initiatives. “

For the study, Brochu and colleagues used publicly available population data from the U.S. census, mortality data from the WONDER system of the Centers for Disease Control, and green data from NASA’s Landsat satellites. to conduct a nationwide health impact assessment that estimated the increasing impact of green vegetation for all causes. mortality among adults age 65 and older in 35 major U.S. metropolitan areas. The study period focused on three different time periods over a 20-year period: 2000, 2010, and 2019. Using the standardized vegetation difference index (NDVI), a widely used metric that estimates the amount of vegetation green, researchers estimated 34,080 -38,187 elderly deaths; or between 15 and 20 deaths per 10,000 elderly people-; they could have been avoided between 2000 and 2019 with a 0.1 NDVI increase in the 35 metropolitan areas.

They estimated that global greenery increased 2.86 percent between 2000 and 2010 and 11.11 percent between 2010 and 2019, with the largest regional increase observed in the south (from .40 percent in 2000 to, 47 percent in 2019).

Brochu points out that greening may not be feasible in all cities due to differences in climate, water sources, urbanization, and landscape, but planners may use the results of the study to examine changes. local in the green over time and develop appropriate and effective climate action. plan in your cities.

“The increase in greenery in an arid southwestern climate is different from the increase in greenery in an urban area of ​​the Pacific Northwest,” says Brochu. “If the climate in an area makes it difficult to plant lush trees, planners can use this greenery data as a starting point and consider other types of vegetation that may be more realistic for their local climate.”

“One of the main questions that urban planners ask is where they should implement greening, and we can quantify the impact of greening initiatives for them, because there is a cost to planting greenhouses. trees or the planting of shrubs, “says the study’s lead author, Dr. Kevin Lane, Assistant Professor of Environmental Health. “Being able to target which areas would have the highest mortality reduction may justify these campaigns, not only as a mitigation measure, but as a way to directly improve health.”

One component of this assessment also reported a case study on the health impacts of the uneven distribution of greenery in Louisville, Kentucky, which was published in The Lancet Countdown’s 2020 report on climate and health. The case study estimated that a small increase in greening could have prevented 400 deaths among adults 55 and older in the Louisville metropolitan area.

Researchers hope to further explore local changes in the distribution of greenery in other urban areas and how these changes may have informed cities ’climate action plans. That analysis could also be replicated globally, thanks to satellite-based NDVI measurements, Lane says.

“One of the great advantages of using satellite-based measurements is that we can compare health impact assessments of US mortality with those made in Europe and other areas, so that we can understand the global impacts of mortality, “says Lane. “This work will allow us to quantify whether a potential strategy for climate change adaptation could have impacts not only on our urban areas, but around the world.”

At SPH, the study was co-authored by Dr. Patrick Kinney, Professor of Urban Health at Beverly A. Brown, and Dr. Marcia Pescador Jimenez, Assistant Professor of Epidemiology. The study was also co-authored by Dr. Peter James of Harvard Pilgrim Health Care and Harvard TH Chan School of Public Health.


Boston University School of Public Health

Magazine reference:

10.3389 / fpubh.2022.841936

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