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The most important tool for cutting urban pollution

By | July 19, 2012, 9:52 AM PDT

It’s no surprise that plants clean up our air, but just how much of a positive impact they can have on urban pollution is now more clear.

New research, which was published this week in the journal Environmental Science and Technology, shows that green walls and other plant infrastructure (as simple as trees and bushes and as complex as green walls) could reduce pollution in urban environments by as much as 30 percent. According to the researchers, green infrastructure — specifically green walls of grass, climbing ivy, and other plants — is more than 10 times more effective at reducing pollution than previously thought.

“Urban canyons,” where streets are surrounded by tall buildings made of concrete and glass, were the focus of the study. It’s in these urban areas where people are exposed to the highest levels of pollution. When researchers used computer models to show the impact of plants in these street canyons on pollution compared to plants in parks or on roofs, green walls were the most effective at removing pollution. Street trees, on the other hand were less effective in street canyons because they trapped pollution at ground level, but were effective on less polluted streets. The researchers also suggest “green billboards” as a way to increase the amount of plants in street canyons.

Up until now, every initiative around reducing pollution has taken a top-down approach – scrapping old cars, adding catalytic converters to cars, and bringing in the congestion charge – some of which have not had the desired effect,” said Rob MacKenzie, a professor at the University of Birmingham and one of the authors of the study, in a news release. “The benefit of green walls is that they clean up the air coming into and staying in the street canyon – planting more of these in a strategic way, could be a relatively easy way to take control of our local pollution problems.

[h/t BBC]

Photo: Flickr/Bill Anderson

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Tyler Falk

About Tyler Falk

Tyler Falk is a contributing editor for SmartPlanet.

Tyler Falk

Tyler Falk

Contributing Editor

Tyler Falk freelance journalist based in Washington, D.C. Previously, he was with Smart Growth America and Grist. He holds a degree from Goshen College.

Follow him on Twitter.

Tyler Falk

Tyler Falk

Tyler does not have financial holdings that would influence how or what he covers.

He writes for SmartPlanet and is not an employee of CBS.

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0 Votes
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Cutting emissions too
Cutting emissions by significantly more efficient engines/boilers etc also works.

It also has the benefit of reducing your energy bills, significantly lengthening your national energy reserves, and improving your energy security by lowering your dependance on tin pot dictators or monarchies in the dodgier Oil Producing States of the world.

I've also heard tree's do a magnificent job of carbon capture and storage - no requirement for complex chemical engineering plants sucking down exhausts, or barking mad scheme's to liquify/compress Co2 and pump it into old salt mines of oil wells underground.
Posted by neil.postlethwaite@...
Updated - 20th Jul
+1 Vote
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Urban Green Corridors
There is little doubt that adding significant vegetation to urban walls would/could reduce urban pollution - but how much water will it take to keep the walls green and how is that impact calculated compared to the reduced pollution. This is exactly why solutions are never simple - synergies exist all around and live by the adage - one action bears multiple reactions.
Posted by WGJConsulting
20th Jul
0 Votes
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condenser & sump water
There's a huge amount of ambient water removed through sump pumps and cooling coil condensers that could be used to water the extra plantings. Combine this with reductions in the urban heat island effect and the impact would be even larger overall.
Posted by kilrwat
20th Jul
+1 Vote
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Good idea, useful and also beautiful.
Who's paying for it?
Posted by opcom
Updated - 20th Jul
0 Votes
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Who is paying?
To opcom: Taxpayers pay, this is something where everyone would benefit.
Posted by k8 br
20th Jul
0 Votes
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Other benefits
Most places, green walls will improve the appearance of an area, even if not done as artistically as in the photo. They'll also provide shelter for birds, animals, and insects that may be beneficial, annoying pests, or something in between.
Posted by theotherwill
20th Jul
0 Votes
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People should be careful what they ask for.
Your observation is spot on. - - They'll also provide shelter for birds, animals, and insects that may be beneficial, annoying pests, or something in between. - -

The city of Boston has tried for decades to keep up and expand green spaces within the city. They have largely succeeded with some unintended side effects.

Squirrels, possums, skunks and coyotes have proven to be very adaptable to urban life. It is amazing how little green space they need to survive. Going out for dinner and a show in the theater distinct can go horribly wrong when you run into a skunk. No one has been attacked YET, but reports of dog walkers being stalked by coyotes are increasing. Little yapper dogs look good to a hungrey coyote.

The restoration of small wetland areas along local streams and rivers has increased the downtown mosquito population that hardly existed 30 years ago. Not a welcome thing when West Nile Virus and EEE are showing up more in trapped mosquitos.

You have to take the bad with the good.
Posted by Hates Idiots
Updated - 24th Jul
0 Votes
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The Most Important Tool...
The most important tool for cutting urban pollution...is that everyone with cars and trucks, move to the country. (waiting for the laugh...;)

Seriously, the most important tool for the pollution problem is, by far, "the human mind"!

All we have to do, is make the simple decision, that we have had enough of burning fuels. It's a hard habit to quit after a million years or so of it! Perhaps the UN ruling that finally put diesel exhaust in the "known carcinogen" category recently, will make some difference.

A 30 percent reduction from Nature is fine, but as humans, I know we can do way better than that. Clean plasma-based energy technology has arrived...but our current oil-based viewpoint is blinding us to the possibility of an abundant, zero pollution, future.

I say, let's grow lots of plants in the cities...but open our minds to zero tolerance for air pollution as well!
For example, check out what Keshe Foundation is doing with plasma-based technology.
Posted by mrfixitrick
20th Jul
0 Votes
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paved front gardens need planning application!
This issue has been acknowledged in Germany for years. There you hardly anywhere get a planning application to fully pave your front gardens. We need to introduce this here soon.
http://www.guardian.co.uk/environment/2012/jul/18/front-gardens-paved-parking-spaces?commentpage=last#end-of-comments
Posted by funnoy
21st Jul
+1 Vote
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Small beer compared to other development
This is small beer compared to the vast swathes of concrete and tarmac laid by developers of housing, retail, yet another (development subsidy funded) warehousing/industrial estate even though there are acres of vacant property begging for tenants, road schemes, pedestrianization schemes etc.

Also who want's a cat toilet on their front garden -Eew !!

If people are worries about drainage, councils and water companies actually cleaning drains out is a good solution - numerous around where I live are blocked with years of accumulated crap, some have small shrubs growing out of them - so long it has been since any Preventative Maintenance occurred.
Posted by neil.postlethwaite@...
25th Jul
0 Votes
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but small beer also helps
When it is brewed with used ingredients from a previous batch of beer.
Posted by atoms
27th Jul
0 Votes
+ -
People should be careful what they ask for.
There is little doubt that adding significant vegetation to urban walls would/could reduce urban pollution - but how much water will it take to keep the walls green and how is that impact calculated compared to the reduced pollution. This is exactly why solutions are never simple - synergies exist all around and live by the adage - one action bears multiple reactions.
Posted by babaluuu
17th Mar
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