Artificial trees, smog-free towers, and other air-purifying urban structures

The mayor (centre) of Toulouse, France unveiling the city's pollution-absorbing artificial tree in September. Photos: AFP

The French city of Toulouse is currently trialing a new addition to its urban landscape. An artificial tree can suck up pollution and release clean air – and could soon be coming to other city centres. But this isn't the first air-purifying concept out there. In fact, there's no shortage of ideas for eliminating fine particles, from green walls to advertising billboards.

An artificial tree

Since mid-September in the southwestern French city of Toulouse, a start-up has been trialing a new generation of air purifier that can help tackle pollution. This futuristic structure actually features microalgae that feed on carbon dioxide – like plants – and release oxygen.

Kyanos Biotechnologies claims that this 5m-tall air purifier could "recycle" 200,000m³ of air each year. Concretely, this artificial tree could capture as much carbon as 100 regular trees. This innovative new piece of street furniture will stay in the city until next spring.

The Smog Free Tower was first installed in 2016 in Beijing.

A living wall

Is it a bench or is it a living wall? You may already have stumbled across the CityTree, this new breed of street furniture currently located in London's Piccadilly Circus, as well as in Amsterdam and Oslo.

It is the work of a German company called Green City Solutions.

This living wall rises up 4m tall above its integrated benches and comprises 1,600 pots of mosses and plants. As a result, this street furniture captures fine particles and cleans the air as much as 275 trees together.

The CityTree features a rainwater tank that keeps the plants watered and its irrigation system is powered by solar energy.

A giant tower

A smog-busting billboard installed in Monterrey, Mexico that uses a special resin that can transform smog into cleaner air.

This idea hails from Dutch designer Daan Roosegaarde. The inventor is believed to have made the world's biggest air purifier, which, standing 7m tall, can capture 30,000m³ of air per hour, as well as 75% of fine particles. Thanks to patented ionisation technology, this tower is able to produce smog-free air.

The Smog Free Tower was first installed in 2016 in Beijing. In fact, pollution in the Chinese capital inspired the designer's concept when he realised that smog was preventing him from seeing the city properly.

The invention won the Successful Design Award China in May 2020. The Smog Free Tower has since branched out worldwide with versions in the Netherlands and China.

A billboard

Daan Roosegaarde seems to have made it his mission to roll out new concepts on the theme of urban air purification. His latest invention, a smog-busting billboard installed in Monterrey, Mexico, uses a special resin that can transform smog into cleaner air.

This technology is based on photocatalysis, harnessing the action of sunlight to break down pollutants. This offers a new line of research for purifying air without relying on photosynthesis. – AFP Relaxnews