Being raised in a rural village in Belgium, living in the busy and polluted city of Barcelona makes me crave for some fresh air every now and then. I am certainly not the only one. 90% of the world’s urban population is breathing polluted air. Sometimes called the silent killer, air pollution is responsible for nearly half a million premature deaths a year in Europe alone. I know everyone is freaking out about ISIS right now, but the real killer is all around us and we have created it ourselves.

A CityTree installed in Oslo is drawing attention (photo: Oslo Phototour)

Luckily, there are some smart guys that took up the challenge to do something about it. With the CityTree, German start-up Green City Solutions has developed a high-tech air purifier that helps cities reduce their air pollution in a compact and profitable way. The CityTree can best be described as a large natural filter that eats up the pollution in the surroundings. The four by three meters large wall is covered with moss at both sides which filter out NOx, particulate matter and CO2 and turn it into biomass. The company claims one CityTree is as effective as 275 trees. 275, gosh! In addition, it retains water during heavy downpours and has a cooling effect in the immediate surroundings. The device runs on itself, thanks to a rainwater recovery system and some solar PV panels.

Equipped with sensors, the smart installation also serves as a pollution sampling station and alerts the operator when its time for maintenance. Including a wifi hotspot or interactive billboards is being considered.

Now, this sounds like the wet dream of the mayors of cities like Barcelona, London or Bejing, no? They are struggling to get air pollution under control, keeping temperatures pleasant during ever hotter summers, and avoiding flooding during intensified rain. The CityTree ticks all the boxes! No wonder there has been a huge interest. They have currently been installed in cities like Berlin, Paris and Hong Kong.

This kind of start-ups always makes me a little bit jealous that I didn’t come up with this idea myself. Truly a great solution with a lot of potential!

The four founders of Green City Solutions next to their brainchild (photo: Green City Solutions)