Green Cleaning in a Different Way

It’s common knowledge that Hong Kong has some of the world’s worst air quality, given that rampant industrial expansion, a reliance on automobiles and a lax regulatory environment mean that air pollution often goes unchecked. But a German architect is applying his design skills to do something about it.

Dénes Honus has founded Green City Solutions, and has come up with a novel way of “eating” air pollution. His company has designed something called CityTrees, a vertical garden of sorts that employs pollution-eating moss as its greenery. Each CityTree unit resembles a vertical ramp, with the greenery attached to the side wall and benches situated at either end.

According to Honus, German universities gave him the idea, as they were doing extensive research into moss cultures and their ability to “eat” air pollution. Bacteria on the surface of the moss attracts particulate matter, which in turn is absorbed by the moss.

The first of the vertical garden CityTrees were installed in Germany, with additional units located in Norway, France and now Hong Kong. Each unit is self-sufficient, with water tanks storing rainwater and a solar panel powering a sensor to determine when the moss needs to be irrigated.

Each CityTree is as effective at combatting air pollution as 275 planted trees, but takes up significantly less space. And, according to Honus and research from the University of Hong Kong, 200 CityTrees would reduce air pollution in a city by 30 percent or more.

An added bonus: the dense, dark green moss becomes a design element in parks and plazas, breaking up the drab look of concrete sidewalks with a splash of color.