Every year, between 3 and 4 million people around the world die as a result of air pollution and its lifelong impacts on human health, from asthma to cardiac disease to strokes. Each summer, thousands of unnecessary deaths result from heat waves in urban areas. Studies have shown that trees are a cost-effective solution for both of these challenges.
Yet investment in planting new trees—or even caring for those that exist—is perpetually underfunded. Despite the overwhelming evidence cities are, on average, spending less on trees than in prior decades.
And too often, the presence or absence of urban nature—and its myriad benefits —is tied to a neighborhood’s income level, resulting in dramatic health inequities. In some American cities, life expectancies in different neighborhoods, located just a few miles apart, can differ by as much as a decade. Not all of this health disparity is connected to the tree cover, but researchers are increasingly finding that neighborhoods with fewer trees have worse health outcomes, so inequality in access to urban nature makes worse health inequities.