Urban Green Infrastructure: Green Walls May Cut Urban Pollution

In the cities, the green wall which have vegetated surfaces not only look beautiful but also have other benefits as well, including cooling city blocks, reducing loud noises, and improving a building's energy efficiency. Some studies show that green walls can potentially reduce large amounts of air pollution in what's called a "street canyon," or the corridor between tall buildings due to the green wall in a street canyon could trapped or absorbed large amounts of nitrogen dioxide and particulate matter.

The green wall systems usually have built-in irrigation systems in which water is harvested at the bottom of the wall and recirculated back to the top. The types of plants on green walls differ, but can include grasses, vines, and other climbing plants—all of which must have strong root structures, Green Roofs for Healthy Cities'

Because a green wall's vegetation is working with a much smaller volume of air in a street canyon, it's more effective at absorbing or trapping the pollutants than if it was tackling a whole mass of air above the city. London and some cities in Western European countries have had trouble keeping air pollution in check—making green walls a possible solution. In addition, the green walls may improve your mood as well as your health.