Dutch designer Daan Roosegaarde has come up with a gem of an idea: air-purifying towers that subject the carbon in smog to such enormous pressure that it is converted into diamonds.

1. Diamonds in the sky

Dutch designer Daan Roosegaarde has come up with a gem of an idea: air-purifying towers that subject the carbon in smog to such enormous pressure that it is converted into diamonds. The diamond can then be used to fund more towers. Beginning in heavily-polluted Chinese cities, Roosegaarde inaugurated the first tower during Beijing Design Week in 2016. His goal is a future with cities so clean that “these towers are no longer needed”.

2. Unmanned pollution-fighting

What’s that buzzing in the smog-filled air? Why, it’s an unmanned smog fighter! In 2014, Chinese media reported that drones fitted with a paragliding wing and a device to freeze smog particles in the air are to undergo testing. An exciting idea, although less reassuring was the news that particles frozen by the drones would then smash to the ground.

3. Cleansing artificial rain

We all know that the air can feel cleaner after it rains, but did you know that so-called cloud seeding has long been used to produce artificial rain? It’s a method that is now being studied as a way of helping to clean up smog in Delhi. ­However, there are concerns about the toxicity of silver iodide, the chemical compound used to start the process.

4. Refreshing high altitude forests in Milan

Two green forests stand tall amid the boisterousness of Milan. This is Bosco verticale, a pair of skyscrapers that house 400 residential units and have received incredible attention for their ­innovative green concept. The buildings’ 21,000 plants generate oxygen, absorb carbon dioxide and reduce noise.

5. A vision of the future

Imagine a city of people running around screaming like a science fiction film. Well, if a new speculative proposal by Chinese designers Shi Jianwei, Hao Tian and Huang Haiyang comes to pass, it’s a situation we may face. The designers have proposed a series of squid-like creatures hovering high in the air that would be able to capture and process pollution in urban environments. The dream of fresh air has never looked more futuristic.