We all know how relieving a good shade tree can be on a 100-degree day. But what if trees could dramatically reduce heat-related illnesses and deaths in our world's hottest cities?
Researchers recently published findings in the International Journal of Biometeorology about how increased tree cover and reflective surfaces could reduce emergency room visits in Los Angeles. The study is critical because rising temperatures impact human health and increase heat-related morbidity rates in hot, dry, urban areas.
Wired reported that simple acts such as planting more trees and painting roofs white could cut the city's heat-related ER visits by up to 66%. The researchers' conclusions build upon assessments that these types of sustainability measures could prevent 25% of heat wave-related deaths.
Fewer ER visits mean less strain on the city's medical system and healthier L.A. residents, especially children and older adults whose bodies can't cool themselves properly or who suffer from breathing conditions exacerbated by extreme heat. Tree-filled areas are often 15 degrees cooler than industrialized neighborhoods with no green space, and researchers are studying which trees will be the most resilient to rising temperatures in the years ahead, as Wired detailed.
Because of differences in tree cover and building materials, the "urban heat island effect" varies significantly between city neighborhoods and houses on the same block. To improve human health outcomes, it's ideal to start planting trees in cities' most vulnerable neighborhoods while educating and collaborating with residents so that they understand the cooling benefits and life-saving potential.
However, as Wired noted, urban forest additions such as the ones proposed for L.A. will need steady attention to reduce risks, including branches falling on vehicles or blocking power lines.
"We want to do planting, maintenance, and then preservation. So keeping existing mature trees in place is actually really critical to canopy expansion," said Rachel Malarich, the city forest officer of Los Angeles.
Along with other urban cooling technologies such as heat-reflective paint and rooftop gardens, trees give us the hope of saving lives while beautifying city spaces and making our homes more livable.
"While it's generally a feel-good kind of investment for cities, we need to tie those investments to public health outcomes because the improvements that can be made are really meaningful," said Edith de Guzman, a University of California, Los Angeles environmental researcher, co-author of the study, and the co-founder and director of the Los Angeles Urban Cooling Collaborative.
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