A man holds a placard at a rally appealing for a reduction of motor vehicles' use at the Place du Chatelet in Paris, capital of France, on Dec. 17, 2016. A new peak in air pollution forced Paris authorities to restrict traffic in French capital on Dec. 16 and Dec. 17. Vehicles, heating systems and wood burning have caused smog spike, the country's worst and longest pollution in a decade. (Xinhua/Chen Yichen)
