Green Walls Clean The Air

BY ON May 1, 2013

Building with green walls

A few weeks ago, while walking down Madrid’s Paseo del Prado, I came upon a lush, textural wall of plants. “How beautiful!” I gushed to my husband. As it turns out, the wall is more than just a pretty facade, it has a practical purpose as well. Green walls like this one are yet another tool for reducing urban air pollution.

In the same way that houseplants filter out toxins and improve indoor air quality, outdoor vegetation helps control air pollution in “street canyons” — areas between tall buildings that trap pockets of polluted air.

A recent study found that within these canyons, green walls, like the one I saw in Madrid, can reduce street-level concentrations of nitrogen dioxide by as much as 40 percent, and concentrations of particulate matter by as much as 60 percent.

According to the study’s authors,

judicious use of vegetation can create an efficient urban pollutant filter, yielding rapid and sustained improvements in street-level air quality in dense urban areas.”

In addition to improving outdoor air quality by acting as living air filters, these walls provide several additional environmental benefits. For example, they help alleviate the heat island effect, make the building they grow on more energy efficient, lower noise — and they improve indoor air quality as well.

The green wall I spotted in Madrid, is one of several found in cities throughout Europe.

When beauty and function combine as they do in these walls, I am gratified. I am, after all, a proponent of rethinking our cities to make them greener and more sustainable.

Yet, as effective as these walls may be in reducing air pollution, their function is to control hazardous pollutants rather than prevent them from fouling our air in the first place.

That is why we must continue to push, and push hard for proactive measures to prevent toxins from entering our air. We must demand a plan to reduce carbon emissions — the only way to slow down climate change.


TOPICS: Clean Air Rules and Regulations, Climate Change, Indoor Air Pollution, Pollution, Soot, Toxics