Team founders

City Tree: tackling air pollution in our concrete jungles

Jan 4, 2018 - 3min read

A few years ago a diverse group of students from Dresden University came together from a range of specialisms, including architecture, horticulture, mechanical engineering and IT, with a bold goal in mind: to improve air pollution in our cities.

After graduating, the team created Green City Solutions and unveiled the City Tree which uses moss to remove pollutants from the air. Each City Tree absorbs 250g of pollutant particles a day, cleaning the air within a 50 metre radius. Since 2014, City Trees have been ‘planted’ in 20 locations across Europe, and one in Hong Kong.

City Trees in situ


With 55% of the global population living in urban areas – and that number estimated to climb to 80% by 2050 – we have to find ways of cultivating green spaces in densely packed cities. In any metropolis, land is an expensive commodity, so urban planners need creative solutions like the City Tree which can deliver the benefit of 275 trees in a staggering 1% of the space.

Co-founder Liang Wu sees the air pollution in Shanghai – where his family live, and a dense smog pervades the cityscape – as a blaring call to arms for him to pursue a sustainable solution. When Wu returned to China for an internship he developed asthma within 2 months; now he wears a protective mask whenever he visits.

City tree in Glasgow


Wu’s story is by no means uncommon. WHO says that 4 out of 5 city residents worldwide face toxic levels of particulate air pollution from poisonous nitrogen dioxide and other carcinogenic particles. This places half of the global population at greater risk of developing asthma, heart disease and lung cancer. WHO links toxic levels of air pollution to over eight million deaths each year. In the EU alone, this costs around $1.6 trillion in economic damage.

“This particular moss culture was developed for its large surface area and for its quick growth.”

The City Tree brings a whole new meaning to the phrase concrete jungle. This is a man-made ecosystem that enhances the natural function of plants to clean the air we breathe.
This particular moss culture was developed for its large surface area (making it more effective at absorption) and for its quick growth (allowing for near-instant implementation). By absorbing 250g of particles every day, City Trees remove a whopping 240 metric tons of CO2 from the air every year.

City Tree in Glasgow


The innovation doesn’t end there, however; Green City Solutions has elegantly entwined two man-made ‘ecosystems’ by connecting their City Trees to the Internet of Things. 

Powered by solar panels, each City Tree has WiFi-enabled sensors that measure the quality of the surrounding air. The same sensors collect environmental and climate data allowing them to regulate and control the unit, which stores and automatically redistributes rainwater for its own irrigation. This tree can virtually ‘think’ for itself. 

“Each City Tree absorbs 250g of pollutant particles a day.”

The high-tech tree camouflages perfectly with its surroundings. A concrete body nestles comfortably among tower blocks and office buildings. The City Tree comes with the option of an attached bench, and can also function as an analogue billboard, displaying images or communicating digital data with onlookers via a QR code. 

An imaginative blend of cutting-edge technology and botanical engineering, the City Tree caters to our biological needs while appealing to consumer demands.