CityTree pollution ‘moss filters’ launched in Westminster

Westminster city council is hosting a trial of a ‘living wall’ moss technology, dubbed the CityTree, which it is claimed has the capability to remove air pollutants from the air.

CityTree, which has been developed by German green technology firm Green City Solutions uses a combination of mosses, cultivated to thrive in urban areas. According to the developers, the installation is capable of removing air pollutants including nitrogen dioxide and particulate matter from the surrounding area by up to 30%.

The CityTree installation at Glasshouse Street, near Picadilly Circus

The CityTree provides the shade and moisture that would otherwise prevent mosses from developing in a city environment.

The installation powers itself via solar panels, and rainwater is collected and automatically redistributed using a built-in irrigation system.

Launched on Friday (16 March) on Glasshouse Street, near Piccadilly Circus, CityTree has been brought to London by The Crown Estate, with the support of Westminster city council. The technology has previously been trialled in Berlin, Paris, Amsterdam and Oslo. It is being supplied in the UK by green technology firm Evergen Systems.

Each CityTree is capable of reducing particulate matter by up to 30%, and is particularly effective in pollution hotspots and areas with high dwell-time the developers claim.

The wall of irrigated mosses also produces a cooling effect on the surrounding area, helping to combat the urban heat island effect.

Air quality

Commenting on the installation, Cllr David Harvey, Cabinet Member for the Environment, Sport and Community at Westminster city council said: “It will be fascinating to see what impact The CityTree has on pollution in the local area. This is just one example of the new technology we want to test across Westminster. Air quality is the number one concern for our residents and with over a million people moving into and travelling to our neighbourhoods each day it is crucial that we make more strides to clean up our air and tackle poor air quality for residents and visitors alike.

“It is going to take a wide range of measures to tackle pollution in central London. The ten pledges set out in our Air Quality Agenda outlines policies to make a real difference – whether it’s reducing the number of dirty journeys, introducing new cleaner technology or encouraging better habits — we want Westminster to be an example for cities across the world.”


Peter Sänger, Founder and chief operating officer of Green City Solutions said: “In a short time, the CityTree has already become established as an effective way to create clean air environments in some of Europe’s most polluted cities. We are delighted that London can now be added to this list and hope to see many more CityTrees across the country in the years to come”

Sukhbir Sidhu, founder and chief executive of Evergen Systems said: “In 2016, we started looking into technologies for cutting air pollution. Getting the CityTree to London has been a two year journey and we are very excited about the future for clean air in our towns and cities.”

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