This report promotes a relatively simple solution to the problem of increasing heat and air pollution in cities: plant more trees. Trees cool the air by casting shade and releasing water vapor, and their leaves can filter out fine particulate matter (PM)—one of the most dangerous forms of air pollution, generated from burning biomass and fossil fuels.
The report documents analysis that tree planting efforts could improve the health of millions of people, and that trees are as cost-effective as many other common solutions. The report also shows that most of the cooling and filtering effects created by trees are fairly localized, so densely populated cities—as well as those with higher overall pollution levels—tend to see the highest overall return on investment (ROI) from tree plantings.
