Chinese cities are using water cannon to clean their air

Beijing’s Tiananmen Square during “dangerous levels” of air pollution in February 2014. Image: Getty.

In the summer months, Chinese cities don’t just get hot: they get smoggy, too. Beijing has long been known as the country’s pollution capital, but data released in March showed that, in 2013, nine other cities suffered more days of smog than the capital. The news prompted Chinese premier Li Keqiang to “declare war” on pollution.

And that war is being fought using cannon.

Over the last few months, pictures have emerged showing giant, hair dryer-like machines, mounted on trucks in the streets of several Chinese cities. These can blow water vapour up to 200 feet into the air: the idea is that water droplets from these “mist cannons” stick to pollution particles, and pull them to the ground.  They come with a hefty price tag: most cost city governments between 700,000 and 900,000 yuan (that’s $113,500-$146,000).

The cities that have made greatest use of the cannon seem to be those of Heibei, the province south of Beijing, where many of the cities with the worst pollution are located. Here’s one in Zhangjiakou:

zhangjiakou.jpg

Image: Xinhua.

Unfortunately for city governments and their war on pollution, Pan Xiaochuan, an environmental expert from Peking University, told Xinhua last month that the cannons aren’t actually very effective. The machine can reduce pollutants for a short time after the water is sprayed, he said – but “its effects don’t last long”. And then the cannon moves on, to another location: it offers, at best, a moment of relief.

Despite this, the cannons are still being used: Chongqing started using one just last week, though city officials say it was hired to fight “summer heat”, not smog.

Peoples Dail.png

Chongqing’s new cannon. Image: People’s Daily.

In other words, they’ve basically spent around 750,000 yuan ($121,500) on a movable sprinkler to keep the city cool. Can’t argue with that.

 
 
 
 

Podcast: Beyond the wall, with John Lanchester

A sea wall in Japan. Image: Getty.

This week it’s another live episode, of sorts. In early April I was lucky enough to chair an event at the Cambridge Literary Festival with the journalist and novelist John Lanchester.

John was mostly there to promote his latest novel, The Wall, a “cli-fi” book about a Britain trundling on after catastrophic climate change has wiped out much of the planet. In the past he’s also written about other vaguely CityMetric-y topics like the housing crisis and the tube - so he’s a guest I’ve been hoping to get on for a while, and was kind enough to allow us to record our chat for posterity and podcasting purposes.

Incidentally, I didn’t find a way of turning the conversation to the tube. We do lose ten minutes to talking about Game of Thrones, though.

The episode itself is below. You can subscribe to the podcast on AcastiTunes, or RSS. Enjoy.

Jonn Elledge is the editor of CityMetric. He is on Twitter as @jonnelledge and on Facebook as JonnElledgeWrites.

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