Dive Brief:

• The urban heat island effect can harm city residents’ cardiovascular and respiratory health, particularly in lower-income neighborhoods, and lead to premature deaths in some cases. Adding more trees as cooling agents to the urban environment could prevent some of those deaths, according to findings from a modeling study published this week in The Lancet, a global research journal.
• Researchers conducted a health impact assessment looking at data from 93 European cities during the summer of 2015, per a research summary. They found that one-third of the premature deaths attributed to higher temperatures that summer could have been prevented by increasing urban tree cover to 30%, but average tree cover in European cities stands at about half of that at 14.9%.
• The authors say it’s the first study looking at how increased tree cover could prevent premature deaths. “Our ultimate goal is to inform local policy and decision-makers about the benefits of strategically integrating green infrastructure into urban planning to promote more sustainable, resilient and healthy urban environments and contribute to climate change adaptation and mitigation,” said lead author Tamar Iungman in a press release.

Dive Insight:

While the study examined heat in Europe, heat-related deaths are rising in the U.S. It’s not just an issue in traditionally hot cities. For example, following the heat dome over Portland, Oregon, in summer 2021, Multnomah County reported that 72 people died due to heat-related illness. 

The concept of green infrastructure as a means to cool cities, clean the air and better handle rainfall is getting increased attention among cities and national leaders as a multi-beneficial and often affordable solution.

More trees aren’t the whole solution, though. Tree-planting programs must be well-designed for benefits to be distributed equitably, experts say. In New York City, for example, Mayor Eric Adams committed to planting 20,000 trees each year for the next four years, but observers worry that budget cuts at the Parks Department will minimize the ability to properly maintain trees.

The authors of The Lancet study acknowledged that increasing tree coverage should be combined with other strategies to reduce extreme heat exposure significantly. In the U.S., other solutions in hot cities like Phoenix and Los Angeles, for example, have included implementing lighter-colored, reflective coatings to paved surfaces to reduce some of the heat exacerbated in paved urban areas. Miami-Dade County, Florida — one of a handful of local governments with a chief heat officer — also recently released an extreme heat action plan that details potential policies around adding protections for outdoor workers, requiring safe cooling in housing, and more.