GRA
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GCC: Study: plant roadside hedges rather than trees to combat near-road pollution

Mon Jan 07, 2019 5:25 pm

https://www.greencarcongress.com/2019/0 ... edges.html
Urban planners should plant hedges—or a combination of trees with hedges—rather than just relying on roadside trees if they are most effectively to reduce pollution exposure from cars in near-road environments, according to a new study from the University of Surrey.

In a paper published in Atmospheric Environment, researchers from the Global Centre for Clean Air Research (GCARE) looked at how three types of road-side green infrastructure—trees, hedges, and a combination of trees with hedges and shrubs—affected the concentration levels of air pollution. The study used six roadside locations in Guildford, UK, as test sites where the green infrastructure was between one to two meters away from the road.

The researchers found that roadsides that only had hedges were the most effective at reducing pollution exposure, cutting black carbon by up to 63 percent.

Ultrafine and sub-micron particles followed this reduction trend, with fine particles (less than 2.5 micrometers in diameter) showing the least reduction among all the measured pollutants.

The maximum reduction in concentrations was observed when the winds were parallel to the road due to a sweeping effect, followed by winds across the road. The elemental composition of particles indicated an appreciable reduction in harmful heavy metals originating from traffic behind the vegetation.

The hedges only—and a combination of hedges and trees—emerged as the most effective green infrastructure in improving air quality behind them under different wind directions.

Roadsides with only trees showed no positive influence on pollution reduction at breathing height (usually between 1.5 and 1.7m), as the tree canopy was too high to provide a barrier/filtering effect for road-level tailpipe emissions. . . .
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RegGuheert
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Re: GCC: Study: plant roadside hedges rather than trees to combat near-road pollution

Tue Jan 08, 2019 2:17 am

Brits prefer hedges to trees at the roadside. Film at eleven. :D
RegGuheert
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GRA
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Re: GCC: Study: plant roadside hedges rather than trees to combat near-road pollution

Tue Jan 08, 2019 5:29 pm

RegGuheert wrote:Brits prefer hedges to trees at the roadside. Film at eleven. :D
I think mixed is the way to go, combining aesthetics with effectiveness while we transition away from fossil fuels over the next forty years or so. Once the transition is complete, the hedges can be removed again if desired, leaving the trees.

OTOH, my city recently removed or reduced many of the hedges from the downtown area. I'm not sure why, but my guess is that they wanted to limit the number of places that homeless could sleep without being seen from the street by police driving by.
Guy [I have lots of experience designing/selling off-grid AE systems, some using EVs but don't own one. Local trips are by foot, bike and/or rapid transit].

The 'best' is the enemy of 'good enough'. Copper shot, not Silver bullets.

Kluth
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Re: GCC: Study: plant roadside hedges rather than trees to combat near-road pollution

Fri Jan 11, 2019 4:28 am

Man, that reason to remove the hedges sounds sad as hell...

DaveinOlyWA
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Re: GCC: Study: plant roadside hedges rather than trees to combat near-road pollution

Fri Jan 11, 2019 7:59 am

I have never seen a hedge get blown over in the wind blocking the road...
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GetOffYourGas
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Re: GCC: Study: plant roadside hedges rather than trees to combat near-road pollution

Fri Jan 11, 2019 9:42 am

Kluth wrote:Man, that reason to remove the hedges sounds sad as hell...
Yup, but sadly it's a growing trend in urban areas.

https://en.wikipedia.org/wiki/Hostile_architecture
Also known as defensive architecture, hostile design, unpleasant design, exclusionary design, or defensive urban design it is most typically associated with "anti-homeless spikes" — studs embedded in flat surfaces to make sleeping rough, uncomfortable, and impractical.
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