Green walls “clear winner” in reducing pollution

Living Walls Effectively Mitigate Air Pollution – investigators in Karlsruhe, Birmingham, and Lancaster have established that plantings like green walls or even trees, bushes, and creeping plants can improve air quality in cities by up to 30%.

Biochemist Thomas Pugh and colleagues … conducted the street canyon study by utilising a computer model of a green wall with vegetation generic to a Western European city. Noting factors such as building placement and wind speed, they recorded the chemical reactions taking place on the living wall.

A clear pattern emerged showing the street canyon absorbed large amounts of particulate matter and nitrogen dioxide.

Pugh emphasizes that this approach to reducing air pollution doesn’t necessarily require an expensive program but can be done piece by piece.  From a press release from Karlsruhe Institute of Technology (KIT):

In a computer simulation of the air enclosed and chemical reactions influencing the concentration of pollutants in the air, the researchers compared the effects of plants grown directly along the streets with those of plants in parks or on roofs. Green walls were the clear winners. Trees along the road also produced good results, but only in less polluted streets, where the tree tops did not retain the polluted air on the ground. To increase the fraction of vegetation in inner cities, the scientists among others propose a type of “green billboard.”

See more from the American Chemical Society.  All via Living Architecture Monitor, a good source of information on green roofs.