Can sprinklers rinse away the haze?

Spraying water into the atmosphere can cause rapid scavenging, he writes.

He believes this system alongside emission controls could provide a permanent solution to smog.

Yu says China already has much of the infrastructure - high buildings on which to place sprinklers, water and aircraft.

And he believes it would be cost-effective.

"The low-tech nature of this geo-engineering approach has led us to believe that it will cost much less than many other interventions, such as cutting emissions," Yu said in his paper.

Bonuses include removing harmful gases from the atmosphere and street cleaning. Drop size matters. If too small, they'll evaporate before reaching the ground, which would release the particles back into the atmosphere.

But it's easy to ensure the drops are large enough, Yu writes.

"The water could be collected and reused, meaning it would not exacerbate current water shortages."

"If the water collected has been polluted because of very polluted air, then we will need some treatment."

The sprinklers would need to be used daily to prevent accumulation. Yu is confident that this wouldn't be a problem for the public.

"If you can offer a half-hour watering your garden, then you can offer a half-hour watering your ambient atmosphere to keep air clean," he writes.