Tourists wear masks to protect from smog in Shanghai, China, Monday, Dec. 9, 2013. The dirty air that has gripped Shanghai and its neighboring provinces for days is attributed to coal burning, car ... more 
Tourists wear masks to protect from smog in Shanghai, China, Monday, Dec. 9, 2013. The dirty air that has gripped Shanghai and its neighboring provinces for days is attributed to coal burning, car exhaust, factory pollution and weather patterns, and is a stark reminder that pollution is a serious challenge in China. (AP Photo/Eugene Hoshiko) less 
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Associated Press | Photo By AP Photo/Eugene Hoshiko
Tue, Dec 10, 2013 4:00 PM EST