People practise Taiji on a foggy day at a park in Jiaozuo, central China's Henan province, January 28, 2013. China issued a blue-coded alert on Sunday as foggy weather forecast for the coming two days will cut visibility and worsen air pollution in some central and eastern Chinese cities, Xinhua News Agency reported. REUTERS/China Daily (CHINA - Tags: ENVIRONMENT) CHINA OUT. NO COMMERCIAL OR EDITORIAL SALES IN CHINA - RTR3D2UJ