Women wear masks while walking on a bridge during a hazy day in Shanghai's financial district of Pudong December 5, 2013. [Photo/Agencies]

BEIJING - China's state environmental watchdog on Wednesday urged local environmental departments to make air quality information public and respond to public concerns in a timely manner.

Statistics from the national air quality monitoring network showed that 45 cities suffered from heavy or even worse pollution from December 16 to 24, and the cities of Shijiazhuang, Xingtai and Hengshui in north China's Hebei Province experienced nine consecutive days of severe pollution.

The ministry asked local authorities to issue emergency plans promptly and spare no effort to combat pollution.

The heavy pollution has forced the suspension of outdoor building projects and vehicle restrictions in Hebei.

Pollution around Beijing and Tianjin is expected to be dispersed by a cold front that will bring strong winds from Thursday.