A teacher leads her students doing body exercise during class break in a classroom on a foggy day in Jinan

 
A teacher leads her students doing body exercise during class break in a classroom on a foggy day in Jinan
A teacher leads her students doing body exercise during class break in a classroom on a foggy day in Jinan, Shandong province, January 14, 2013. Heavy fog enveloped a large swathe of east and central China, with the city's residents being advised to stay indoors to avoid the heavily polluted air, Xinhua News Agency reported. REUTERS/China Daily