A new study from The Nature Conservancy finds that an investment in tree planting of just US $4 per resident in some of the world’s largest cities could improve the health of tens of millions of people by reducing air pollution and cooling city streets.
Released today at the American Public Health Association annual meeting, the Planting Healthy Air study applies well-established research into how trees clean and cool the air locally at a global scale to identify those places where an investment in tree planting can make the biggest impact on people’s lives.
The Conservancy partnered with the C40 Cities Climate Leadership group to develop the study, with the aim of providing urban leaders with the data they need to demonstrate that investments in tree planting can improve public health in their cities.
“Trees can have a significant local impact on pollution levels and temperatures,” said Rob McDonald, lead scientist for global cities at The Nature Conservancy and the study’s primary author. “Urban trees can save lives and are just as cost-effective as more traditional solutions like putting scrubbers on smokestacks or painting roofs white.”
The challenges facing cities are significant, but trees can be an important part of the solution:
The Conservancy’s Planting Healthy Air study found that an annual global investment of US $100 million in tree planting could provide 77 million people with cooler cities and 68 million people with measurable reductions in particulate matter pollution.
Cities with high population density, high levels pollution and heat, and a low cost of planting trees showed the highest return on investment, with countries like India, Pakistan and Bangladesh topping the global rankings. But the data also shows neighborhoods in every city that offer a high potential benefit to residents from tree planting.
Trees are the only solution that both clean and cool the air, while simultaneously offering other benefits, including urban green space for residents, habitat for wildlife and carbon sequestration. Tree planting is a solution that mayors and other municipal leaders around the globe can implement to improve the lives of residents within their communities, reducing air pollution and slowing climate change.
“Trees alone cannot solve all of the world’s urban air and heat challenges, but they’re an important piece of the solution,” McDonald said.