Sanitation workers clear off wastes drifting on the West Lake amid heavy fog in Hangzhou, capital of east China's Zhejiang Province, Jan. 28, 2013. The provincial meteorological observatory has issued an orange-coded alert on Jan. 28 morning as foggy weather here cut visibility to less than 500 meters and worsened air pollution in many cities. (Xinhua/Yue Deliang) 

Citizens do morning exercises amid heavy fog on a bank of the West Lake in Hangzhou, capital of east China's Zhejiang Province, Jan. 28, 2013. The provincial meteorological observatory has issued an orange-coded alert on Jan. 28 morning as foggy weather here cut visibility to less than 500 meters and worsened air pollution in many cities. (Xinhua/Yue Deliang)

Citizens walk on a bridge amid heavy fog in Hangzhou, capital of east China's Zhejiang Province, Jan. 28, 2013. The provincial meteorological observatory has issued an orange-coded alert on Jan. 28 morning as foggy weather here cut visibility to less than 500 meters and worsened air pollution in many cities. (Xinhua/Huang Zongzhi) 

Citizens do morning exercises amid heavy fog in Hangzhou, capital of east China's Zhejiang Province, Jan. 28, 2013. The provincial meteorological observatory has issued an orange-coded alert on Jan. 28 morning as foggy weather here cut visibility to less than 500 meters and worsened air pollution in many cities. (Xinhua/Huang Zongzhi)