Portland State Magazine Winter 2016

16 pORTLAND STATE MAGAZINE winter 2016 wr i t t e n b y J OHN K I RK LAND Looking at the link between urban trees and health made in the AMERICAN JOURNALIST William Vaughan once called suburbia the place where the developer bulldozes the trees, then names the streets after them. The same is true for cities. After all, how many pine trees do you see on Portland’s Pine Street? How many oaks on Oak Street? Answer: few, if any. Doing away with trees is unhealthy. According to Vivek Shandas, PSU urban studies and planning professor, there is a direct relationship between a lack of trees in urban areas and stressors such as air pollution and elevated heat, called “urban heat islands.” Both are hazardous to human health, especially for the elderly and the very young. And as Shandas discovered, they tend to occur more in lower-income neighborhoods. To show this, Shandas and his colleagues developed a free computer mapping tool ( map.treesandhealth.org ) that displays Portland neighborhoods in terms of their tree coverage, traffic- related air pollution, heat index, level of poverty and relative age of their residents. Once you’ve pinpointed neighborhoods that could use the greatest improvement, the app will tell you how many trees need to be planted to boost their overall livability. Shandas rolled out the Trees and Health app in summer 2015. It includes maps of the Portland metro area and 12 other U.S. cities with populations of 400,000 to 700,000. These are cities that are big enough to have a voter base to push for more trees but small enough that planting efforts would make a difference. His goal is to include all cities in the United States with populations of 100,000 or more. “This is a tool that allows us to predict the highest health benefits from planting trees,” he says. “I want to generate a conversation about how we can think more deeply about social and environmental health and encourage a pragmatic approach to planting trees.” Trees provide numerous well-documented health benefits. They absorb carbon dioxide and produce oxygen, and they also scrub pollutants out of the air. “A single tree can absorb 10 pounds of air pollutants a year and produce nearly 260 pounds of oxygen—enough to support two people,” the American Forests conservation group states on its website. Shandas found that trees d0 an even better job of removing air pollution than was previously thought. In developing the app, he and his research team set up sensors throughout Portland that measured nitrogen oxide, a common air pollutant. While it was commonly thought that trees could reduce nitrogen oxide by 7 percent, Shandas’ sensor research found the figure to be nearly double that. Trees have social benefits as well. Shandas says they slow traffic because drivers are less inclined to speed in areas where trees fill their peripheral vision. He even cites a U.S. Forest Service study in which women had higher birthweight babies in neighborhoods with more mature trees. The thought is that trees are associated with a sense of calmness and wellbeing that affects pregnancy in a healthy way. There’s also a troubling social correlation: wealthier neighborhoods tend to have more tree canopy than poorer neighborhoods. A 2010 study by researchers at Auburn University and the University of Southern California found that trees were viewed as more of a luxury than a necessity—a luxury that was demanded more by people living in affluent neighborhoods. They found that for every 1 percent rise in income, the demand for forest cover increased by 1.76 percent. USERS OF the Trees and Health app can see the stark differences in Portland’s neighborhoods with just a few clicks of a mouse. On one end of the spectrum is the Gateway neighborhood in Northeast Portland—an area at the high-traffic confluence of I-84 and I-205. It SHADE