Xi'an suffers seventh straight day of serious smog (4/4)

A thick blanket of dark grey air continues to loom over the city of Xi'an as it suffers a seventh straight day of serious smog on Dec 24, 2013. Smog has shrouded many cities from western to eastern China, including Xi'an, capital of Shaanxi Province, where air pollution reached the index limit level. The city government launched an emergency response because of the pollution. [Photo: China News Service / Zhang Yuan]