SHIJIAZHUANG - Eleven company owners in Handan city, Hebei province, have been detained for discharging pollution amid severe ongoing smog that has enveloped many parts of northern China.

The city issued a red alert for air pollution on Dec 16. Production at 332 factories has been halted. A total of 630 companies have been ordered to take measures to cut emissions and pollution.

The city government has dispatched over 800 officials to supervise pollution control.

Severe smog in northern China continued to worsen on Tuesday.