Plant-Covered Walls Could Scrub Air for Cities
A new computer model found plant-covered walls could remove significant amounts of air pollution from city streets.
CREDIT: Pack-Shot | Shutterstock.com
Could you imagine plant-covered "green billboards" in your city? Walls covered in greenery could remove 10 to 12 times more air pollution than rooftop gardens, a new computer model has found.
The new model examines how different configurations of plants in cities could reduce pedestrians' exposure to two important air pollutants, nitrogen dioxide and particulate matter. And it's discovered that plants have a much greater impact than previously believed in "street canyons" formed by skyscrapers lining a busy road.
Greenery could remove an average of 7 to 30 percent of the nitrogen dioxide and particulate matter in a street canyon, Environmental Health Perspectives reported. Previous studies found that plants removed less than 1.5 percent of the air pollution in an area. The new model's creators, earth and atmosphere researchers from Germany and the U.K., got higher numbers by focusing on street canyons only. In such environments, plants may act like "an air purifier running in a small, enclosed room as opposed to a large, open space," Environmental Health Perspectives reported.
The researchers suggested cities install green billboards. We've never heard of any plant-covered billboards or walls built specifically to scrub the air, but Walter Warriner, community forester for Santa Monica, Calif., told Environmental Health Perspectives such structures could appear soon. Urban foresters like him have recently started to quantify the benefits of greenery in cities, a trend that may lead them to green walls.
The U.K. and German scientists published a paper about their model in June 2012, in the journal Environmental Science & Technology.