City trees: green infrastructure to help cities clear the air

This long, hot summer has certainly been one to remember. But while many of us have enjoyed the sunshine, the soaring temperatures have had a critical effect on air quality, particularly in urban areas. In London and some other UK cities, pollution warnings were issued during the July heatwave.

The hidden killer

Air pollution in Europe is a bigger killer than obesity or alcohol. In the UK, 40,000 deaths a year are attributable to the effects of poor air quality. During the summer months, cities become heat islands that push air pollution to ever more dangerous levels. This summer has seen reports of increased numbers of people, particularly children, admitted to hospital with breathing difficulties, which many have blamed on air pollution.

As we’ve previously reported, in 2017 and 2018, national, regional and city authorities are acting to improve air quality, and around the world urban planners are trying out innovative ideas to combat the heat island effect. Last year, we blogged about Milan’s Bosco Verticale – a ground-breaking project that installed thousands of plants on the balconies of two residential tower blocks. The towers absorb 30 tons of CO2 a year and produce 19 tons of oxygen a day. Noise and heat are also reduced, and the buildings provide habitat for more than 20 species of birds.

Another innovative product, Voyager, has been developed by Idox Transport to enable road users to monitor travel information, including air quality and road accidents. The comprehensive travel information system helps drivers avoid congestion hotspots and takes the stress out of planning a journey.

Clearing the air

One important way of improving urban air quality is to increase the number of trees and plants in towns and cities. But all too often the barriers to tree planting in urban areas can be hard to overcome.

Which is why the “City Trees” project is so significant. Designed by a German startup, a City Tree is a “living wall” of irrigated mosses with the pollution-absorbing power of almost 300 trees. A rainwater-collection unit is built into the City Tree, as well as a nutrient tank and irrigation system, allowing the assembly to water itself.

Berlin, Paris, Amsterdam and Oslo were among the first European cities to install City Trees, and in the UK they’ve appeared on the streets of NewcastleGlasgow and London

There is evidence that green infrastructure can have significant effects on air quality. However, recent studies have indicated that, while vegetation and trees are beneficial for air quality, they cannot be viewed as a solution to the overall problem of poor air quality. That requires a coordinated approach to tackling the causes of air pollution, including diesel emissions from transport.

City Trees may not have all the answers to tackling the hidden killers in our air, but they are helping to blunt the impact of air pollution, helping us all to breathe a little more easily.


You can read more about efforts to tackle air pollution in our previous blog posts:

Idox Transport provides a range of products and services to support strategic and localised transport control. Its solutions are designed to ease congestion, improve air quality, detect and manage incidents and promote ‘green wave’ travel.

Pocket parks: making cities friendlier, greener and more resilient

derbyshire street pocket park 2

Derbyshire Street Pocket Park, London. Image: Greysmith Associates

By James Carson

Last summer, a report for the Heritage Lottery Fund offered mixed news on the state of public parks in the UK. While increasing numbers of parks were reported to be in good condition, and visitor numbers and levels of satisfaction also rising, the study found evidence that public parks are now facing many significant challenges:

“As public spending has fallen parks have faced large cuts in their funding and staffing over the last three years, and these cuts are expected to continue over much of the rest of this decade.”

It’s heartening, then, to see that a project aiming to create new green spaces is now bearing fruit. This month, the Mayor of London announced the successful delivery of 100 pocket parks across the capital.

Pocket parks are small areas of public space with trees and greenery, places to sit and relax and spaces for people to socialise. They also contribute to making the city friendlier, greener and more resilient, and have been instrumental in contributing to public health in low income areas.

Pocket parks in London

London’s pocket parks scheme, taking in 26 boroughs, has benefited from £2m in funding from the Greater London Authority. The programme has supported local communities and volunteers in rejuvenating and transforming small patches of uncultivated and overlooked land into lush green spaces for everyone to use and enjoy. Some examples give a flavour of the varied and inventive nature of pocket parks:

  • The edible bus stop
    London’s first pocket park provided a blueprint for making small-scale green infrastructure interventions a reality across the capital. The park was created beside the bus stop on Landor Road, Stockwell, by a team of ‘guerrilla gardeners’ working with the local community. This once forgotten space has now been transformed into a thriving garden and neighbourhood hub.
  • Derbyshire Street Pocket Park, Bethnal Green
    This project transformed a dead-end road that attracted anti-social behaviour and fly-tipping into a safe and vibrant community space, incorporating a rain garden, seating areas, a cycle lane and permeable paving.
  • Canning Town Caravanserai
    The current plot of this project, near Canning Town station, is due to be reclaimed by a developer, leaving the community without a permanent space. In response the Pocket Parks team has embraced the idea of moveable growing spaces. The resulting ‘mobile parks’ will provide areas that have limited park access with gardening space and activities.
  • Hackney pocket park
    Residents of Hackney’s Trelawney estate generated many of the ideas that has resulted in this new pocket park, including a space for local people to meet and improved wildlife habitats. The planting scheme acknowledges the site as the location of what was in the 19th century the largest hothouse in the world, with an unrivalled collection of palms, orchids and ferns, which helped influence planting in the rest of the UK.

Pocket parks beyond London

The pocket parks approach is not confined to the UK capital. There are good examples elsewhere in the country and overseas.

In Newcastle-upon-Tyne, the city council and business development company NE1 have been working together on pocket parks. One original idea is Quayside Seaside. Complete with deck chairs, palm trees and buckets and spades, creates a space where the visitors can unwind, build sandcastles and enjoy a free game of volleyball. Originally opened in the summer of 2011, the installation has proved to be so popular that it has become an annual fixture in Newcastle’s calendar of events.

Further afield, pocket parks are providing residents and visitors with oases inside the concrete jungle.

Complementing, not competing

The growth of pocket parks shouldn’t obscure the need to look after our larger public parks. As the Heritage Lottery Fund report observed, “they are deeply rooted in the physical fabric, spirit and identity of thousands of places across the UK”.  Pocket parks should be seen as complementing rather than competing with these bigger green spaces, in helping to make the pressures of urban life a little less stressful for us all.


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