Some of the world’s most polluted cities contain more buildings than air-purifying greenery. To mitigate air pollution, Inhabitat reports that an environmentally conscious German startup has designed a plant-based urban sculpture that it claims has the same air-purifying properties as 275 trees.

Green City Solutions's CityTrees are large, living walls of plants, lichens, and mosses attached to air vents. The greenery absorbs dust, nitrogen dioxide, and ozone gases from the air, and WiFi sensors inside the walls collect data about the types and levels of city pollution, helping officials keep tabs on local environmental conditions. No gardeners are needed, as the sculptures are solar-powered and watered by a reservoir that collects rainwater.

CityTrees have been installed in Glasgow, Oslo, Paris, Brussels, Hong Kong, and other cities. To learn more about how they work, watch the video below.

[h/t Inhabitat]