Cities used cannons to improve air quality data

Environmental chiefs have punished officials in two cities for using mist cannons - devices for clearing smog - to wash pollutants from monitoring stations to improve air quality readings.

The large cannons, usually mounted on trucks, spray a mist of liquid to disperse fine airborne particles. Many cities, including Beijing, now use them to reduce air pollution over a small-scale area.

However, officials in Xinyu, Jiangxi province, have been criticized for deploying the devices to clear the air around an environmental monitoring station in September and October.