The More Trees, the Longer People Live, Reveals New Study

Having more trees in Philadelphia could prevent between 271 and 400 premature deaths per year.
Loukia Papadopoulos

We all love trees. They provide shade and shelter and reduce CO2 emissions but did you know they could also help people live longer? The first city-wide health impact assessment of the effects of tree canopies on premature mortality in Philadelphia has been released and it found some pretty interesting results.


It turns out that having more trees in the city could prevent between 271 and 400 premature deaths per year. The study was led by Michelle Kondo, a Philadelphia-based research social scientist with the U.S. Department of Agriculture Forest Service, and her colleagues. 

The research evaluated the potential impact of Greenworks Philadelphia, a plan to increase tree canopy to 30% across the city by 2025, on human mortality. The work is one of the first to use a tool developed by public health researchers in Spain and Switzerland called the Greenspace-Health Impact Assessment in order to estimate the number of preventable deaths based on physical activity, air pollution, noise, heat, and exposure to greenspaces.

Kondo and her team calculated the annual number of preventable deaths associated with changes in tree canopy in Philadelphia between 2014 and 2025. They looked at three scenarios of urban green space.

The results showed that increasing urban tree canopy to the Greenworks Philadelphia levels could prevent 400 deaths annually. However, even lesser increases in tree canopy still ended up in reduced mortality.

A mere 5% increase could result in an annual reduction of 302 deaths and a 10% increase could achieve a reduction of 376 deaths

"This study supports the idea that increasing tree canopy and urban greening efforts are worthwhile, even at modest levels, as health-promoting and cost-saving measures," Kondo said.

"In recent weeks, as residents of many cities experienced quarantine conditions, we experienced a heightened need for public green space," Kondo added.

"While the COVID-19 pandemic has meant that we need to pay attention to our proximity to other people and take precautions to limit our contact, time outside in parks and forests has been critical to maintaining our mental and physical health."

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