The world’s first bio-tech filter to quantifiably improve air quality. Different types of moss bind environmental toxins such as particulate matter and nitrogen oxides while producing oxygen at the same time. Integrated IoT technology delivers comprehensive information on performance and status as well as environmental data on the CityTree’s surroundings. Controllable ventilation technology allows airﬂow to be intensified, meaning that the filter eﬀect can be increased as required. Mosses store large quantities of moisture, and the considerably increased evaporation surface creates an immense cooling eﬀect.