Each huge cannon costs £90,000 and have been installed by zealous environmental officials in cities across the world’s most populated country.
The 10-tonne cannon shoots thousands of litres of tiny water droplets up to 200ft (600 metres) into the air.
The theory is that the water will then stick to pollution particles and literally wash the air clean by making the dirt fall to the ground.
Machines like this one have been installed in the city of Xi’an in the Shaanxi province, with Chinese press questioning how effective the “removable mist cannons” actually are.
Although the machine can reduce its surrounding pollutants within a short period of time after water is sprayed, its effects don't last long.
Scientists have now conceded the machines are basically useless in fighting air pollution and that their effect could only ever be short-term.
Dr Pan Xiaochuan, an environmental expert at Peking University, said: "Although the machine can reduce its surrounding pollutants within a short period of time after water is sprayed, its effects don't last long."
He said the cannon might be effective on dusty construction sites but does not help to fight pollution particles from coal burning and vehicle emissions.
Cannons are also in operation in Zhangjiakou, Herbei Province, and Lanzhou city in Gansu province.
A separate process called ‘cloud seeding’ has been used repeatedly in China, most notably during the 2008 Beijing Olympics to ensure there was no rain during the opening and closing ceremonies.
Chinese authorities claimed the rockets were successful in forcing rain to fall before the ceremonies, but experts disputed their effectiveness.