Beijing residents spent over half of last year living with dangerous levels of air pollution; some days, the numbers even went far off the charts, beyond what used to be considered the worst possible level of smog.
As more and more people end up in the hospital—or dead—the city announced in January that it will spend around $1 trillion on reducing pollution over the next few years. One scientist thinks some of that money ought to go to an unconventional solution: Giant sprinklers, attached to skyscrapers, that can wash pollutants out of the air.
Shaocai Yu, formerly an employee of the U.S. Environmental Protection Agency, says that spraying water in filthy air would be a quick, cheap, and natural solution and would use technology that exists today. He’s proposing that the idea could be used in all smoggy Chinese cities, not just Beijing. "Water should be sprayed into the atmosphere like watering [a] garden," Yu wrote in the journal Environmental Chemistry Letters.
Rain and snow, Yu points out, are very efficient at cleaning the air. As precipitation falls, it collects polluted particles along the way and deposits them on the ground. Since most urban pollution hangs at low elevations (below 300 feet), a showerhead-like device attached to a skyscraper would be high enough to wash the smog away. Yu says the water could be recycled and used to clear the air multiple times.
The government is already pursuing the idea of seeding clouds with silver iodide to make it rain. But Yu says that process requires clouds in the sky, and even when there are clouds, it doesn't always reliably generate rain.
Though he's an expert on "wet deposition"—the process of how rain cleans air—Yu doesn't yet have proof that his idea would actually work. He plans to carry out tests with students at Zhejiang University and in Hangzhou. In his view, the challenges are primarily in the design.
"I think that most of challenges here are to design the specific spray system that can spray a good rain drop size and rain intensity to have the most scavenging efficiencies for the air pollution," Yu says.
In the meantime, plenty of critics are saying there are practical issues with the idea.
"If they do end up doing this ... people are going to complain about them wasting already scarce water resources," Zhao says. "I don't even think this is a short-term solution, and I just doubt that it will work at all."
Though he believes that some other solutions, like expensive air filters, can work, Zhao says he thinks that the focus should be on reducing pollution at its source and shifting to renewably energy.
"There's not a lot of good short-term options really, except that the government can restrict the number of cars on the road, or shut down certain heavy industries at certain times to cut down emissions to help alleviate the crazy pollution outbreaks," Zhao says.