CityTrees

CityTrees, also known as Robot Trees, Robo-Trees, and Moss Walls, are large air filters installed in many European cities, as well as Hong Kong, that remove pollutants from the atmosphere.

The filters intend to curb harmful emissions from nearby traffic congestion, including fine dust particles and nitrogen oxides, of which they are claimed to take in 80%,[1] although this has been disputed by some experts.

[5] The developers of CityTrees, German company Green City Solutions, previously created the first vertical moss farm in Bestensee, Berlin.

[8] CityTrees have since been installed in Amsterdam, Berlin, Bern, Brussels, Budapest, Cork, Glasgow, London, Oslo, Paris, and Skopje.

[8] The operations director for Cork City, Council David Joyce, said that the CityTrees "are not there to replace a tree", because they perform a different function.

[11][12] Although it has been reported that one CityTree is equivalent to about 275 real trees, Green City Solutions' marketer Simon Dierks told Cork newsletter Tripe + Drisheen that this figure is "four or five years old", "not true", and "not a smart thing to say".

[15] Simon Dierks told Tripe + Drisheen Green City Solutions are working on replacing the earlier iterations of the CityTree with the more recent model.

[16] The newer model, dubbed "CityTree 2020", is made of wood and is a hexagonal shape, which Green City Solutions called a "Bauhaus-inspired design".

At the trial's conclusion, only one-fourth of the plants survived, and experts from the Municipal Health Service and Wageningen University found that CityTrees took in less than 1% of particle matter, instead of the promised 20%.

[25] Waltham Forest Council abandoned CityTrees installed in Leytonstone, following the death of the towers and the quiet removal of projects elsewhere, such as Westminster.