Nav: Home

Cities need to 'green up' to reduce the impact of air pollution

May 16, 2017

The harmful impact of urban air pollution could be combated by strategically placing low hedges along roads in a built-up environment of cities instead of taller trees, a new study has found.

The study, just published in the journal Atmospheric Environment, points out that low hedges reduce the impact of pollution from vehicles in cityscapes where there are large buildings close to roads, far more effectively than taller trees. In some environments, trees actually make the pollution more concentrated depending on prevailing wind conditions and built-up configurations.

The study is a collaborative effort by partners from the UK, Europe and USA, led by the University of Surrey's Professor Prashant Kumar, under the umbrella of H2020 funded project, iSCAPE: Improving Smart Control of Air Pollution in Europe.

Higher trees only have more of an impact in reducing air pollution in areas which are more open and are less densely populated by taller buildings.

Urban air quality continues to be a primary health concern as most of the world's population currently lives in urban areas (54% in 2014), and percentage is projected to rise to 66% by 2050; this is coupled with the fact that one of the main global sources of air pollution in cities is traffic emissions.

Professor Prashant Kumar, who is Chair in Air Quality & Health at the University of Surrey, said future urban planning need to consider designing and implementing more "green infrastructure", such as trees or hedges in the built environment to create a more healthy urban lifestyle.

Green infrastructure in cities is an urban planning solution for improving air quality as well as enhancing the sustainability of cities for growing urban populations. These green solutions include street trees, vegetation barriers (including hedges), green (or living) walls, and green roofs. They act as porous bodies which influence local dispersion of pollution and aid the deposition and removal of airborne pollutants, making the air cleaner.

Professor Kumar said: "We all know air pollution is a major factor of everyday urban life. This comprehensive review highlights that trees and hedges, as well as other green infrastructure, must be used strategically to help create healthier, less polluted cities that are also more pleasant for everyone to live and work in.

"Our other research study into London's air quality, published this week in Atmospheric Environment, investigated the underlining factors responsible for the air pollution exposure in urban environments. The other aspects, such as time of day and wind speed, emerged as important predictors of air pollution exposure for the above-ground modes (car, bus, walk) compared with openable/non-openable windows for the underground trains.

"Our earlier study showed the weathering impact of air pollution on the building materials such as limestone, sandstone and carbon steel, used in many heritage buildings and built infrastructure. This is why we need to protect buildings as well as humans in cities in future urban planning, so the strategic placing of hedges, trees and other green infrastructure can have a direct benefit as an air pollution control measure in cities."

The study also highlighted that green infrastructure has both positive and negative impacts on air quality at street levels, depending on the urban location it is in as well as its vegetation characteristics.

In a "street canyon" environment, where buildings like skyscrapers are close together on either side of the street, high-level green infrastructure (such as trees) generally have a negative impact on air quality. Instead, low-level hedges reduce air pollution exposure in such places. In a similar way, green walls and roofs act as a sink to effectively reduce pollution.

In open road conditions, thick, dense and tall vegetation barriers restrict the freshly emitted vehicle emissions from reaching roadsides in high concentrations where people walk, cycle or live nearby.

Apart from air pollution reduction, other benefits of urban green infrastructure include urban heat island mitigation, the potential reduction in energy consumption, better stormwater management, and climate change mitigation.

Professor Kumar added: "Under the framework of the iSCAPE project, we are currently performing targeted field investigations to quantify the effects of different types of green barriers along the busy open-road sides. This will help to develop evidence-based guidelines to support future urban planning and the public to make informed choices to "green up" their surrounding environments."
-end-
Reference

Abhijith, K.V., Kumar, P., Gallagher, J., McNabola, A., Baldauf, R., Pilla, F., Broderick, B., Di Sabatino, S., Pulvirenti, B., 2017. Air Pollution Abatement Performances of Green Infrastructure in Open Road and Built-up Street Canyon Environments - A Review. Atmospheric Environment, Online link: https://doi.org/10.1016/j.atmosenv.2017.05.014

Notes for editors
  • Road traffic creates many harmful pollutants including particulate matter (PM), ultrafine particles (UFP) and gaseous pollutants such as nitrogen oxides (NOx), carbon monoxide (CO) and sulphur dioxide (SO2). To combat this; urban vegetation removes gaseous pollutants by absorption through leaf stomata or plant surfaces.

  • This study is led by the University of Surrey's team as a part of the iSCAPE (Improving Smart Control of Air Pollution in Europe) project, which is funded by the European Community's H2020 Programme (H2020-SC5-04-2015) under the Grant Agreement No. 689954.
  • More information on the damage done to buildings by air pollution can be found on Dr Prashant's 2013 paper Footprints of air pollution and changing environment on the sustainability of built infrastructure.


University of Surrey

Related Air Pollution Articles:

Spotting air pollution with satellites, better than ever before
Researchers from Duke University have devised a method for estimating the air quality over a small patch of land using nothing but satellite imagery and weather conditions.
Exposure to air pollution during pregnancy is associated with growth delays
A new study by the Barcelona Institute for Global Health (ISGlobal) has found an association between exposure to air pollution during pregnancy and delays in physical growth in the early years after birth.
Nearly half of US breathing unhealthy air; record-breaking air pollution in nine cities
Amid the COVID-19 pandemic, the impact of air pollution on lung health is of heightened concern.
Air pollution linked to dementia and cardiovascular disease
People continuously exposed to air pollution are at increased risk of dementia, especially if they also suffer from cardiovascular diseases, according to a study at Karolinska Institutet in Sweden published in the journal JAMA Neurology.
New framework will help decide which trees are best in the fight against air pollution
A study from the University of Surrey has provided a comprehensive guide on which tree species are best for combating air pollution that originates from our roads -- along with suggestions for how to plant these green barriers to get the best results.
Air pollution is one of the world's most dangerous health risks
Researchers calculate that the effects of air pollution shorten the lives of people around the world by an average of almost three years.
The world faces an air pollution 'pandemic'
Air pollution is responsible for shortening people's lives worldwide on a scale far greater than wars and other forms of violence, parasitic and insect-born diseases such as malaria, HIV/AIDS and smoking, according to a study published in Cardiovascular Research.
Air pollution in childhood linked to schizophrenia
Children who grow up in areas with heavy air pollution have a higher risk of developing schizophrenia.
Air pollution can worsen bone health
A new study by the CHAI Project with over 3,700 people in India associates air pollution with a higher risk to develop osteoporosis.
Depression and suicide risk linked to air pollution
People exposed to higher levels of air pollution are more likely to experience depression or die by suicide, finds a new analysis led by UCL, published in Environmental Health Perspectives.
More Air Pollution News and Air Pollution Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: Reinvention
Change is hard, but it's also an opportunity to discover and reimagine what you thought you knew. From our economy, to music, to even ourselves–this hour TED speakers explore the power of reinvention. Guests include OK Go lead singer Damian Kulash Jr., former college gymnastics coach Valorie Kondos Field, Stockton Mayor Michael Tubbs, and entrepreneur Nick Hanauer.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Dispatch 6: Strange Times
Covid has disrupted the most basic routines of our days and nights. But in the middle of a conversation about how to fight the virus, we find a place impervious to the stalled plans and frenetic demands of the outside world. It's a very different kind of front line, where urgent work means moving slow, and time is marked out in tiny pre-planned steps. Then, on a walk through the woods, we consider how the tempo of our lives affects our minds and discover how the beats of biology shape our bodies. This episode was produced with help from Molly Webster and Tracie Hunte. Support Radiolab today at Radiolab.org/donate.