Green innovations are growing in both presence and popularity. Buildings across the globe continue to be renovated or built to include green aspects, such as gardens on roofs or collecting rainwater. Cities are generally the most affected by pollutants at ground level due to pollution being trapped by buildings which has led to studies on how to reduce ground level pollutants through green innovations.
A study recently published in the journal Environmental Science and Technology studied how to cut pollution in street canyons. Street canyons are formed by skyscrapers and other large buildings blocking pollutants formed on the ground from escaping and diluting. Pollutants common on the ground level include particulate matter and nitrogen dioxide, amongst others.
The team studied computer models of the impact of street canyons on pollution accumulation. The team also studied the impact trees have on removing pollutants at the ground level and how the impact of green walls would alter pollution levels. The team determined that trees did well to remove pollutants but their impacts were limited under increased pollution levels. Also, trees could prevent pollution from leaving ground level if their canopies acted as a shield.
The team determined that green walls, such as those containing ivy and other similar plants, along with trees planted in effective ways on streets could reduce pollutants by thirty percent. The team indicated that alongside greening the sides of buildings, it would be effective to place green walls in various locations similar to billboards.
Co-author of the study, Rob MacKenzie, stated: “Up until now, every initiative around reducing pollution has taken a top-down approach- scrapping old cars, adding catalytic converters, bring in the congestion charge- some of which have not had the desired effect. […] Planting more [green walls] in a strategic way could be relatively easy way to take control of our local pollution problems.”