|Photo taken on Dec. 24 shows the Bell Tower, one of Xi’an’s landmarks, in a thick blanket of grey air. (Xinhua/Wang Zhen)|
Smog covered much of China on Christmas Eve, including Beijing, where air pollution in some areas reached the index limit level.
The air quality index (AQI) for 16 cities exceeded 300 on Tuesday, reaching the most severely polluted level. Of the ten most smoggy cities on Tuesday, seven were in north China's Hebei Province.
Smog on Wednesday will continue until nightfall, when a cold front will bring rain and strong winds.