A visitor wearing a mask waits for the flag-raising ceremony at Tian'anmen Square as dangerous levels of pollution shroud Beijing, Jan 29, 2013. Pollution in the capital has again surpassed the worst alert levels, leading authorities to urge residents to remain indoors. Hospitals reported a rise in admissions for respiratory complaints as the worst smog for decades exceeded the World Health Organization's "healthy" limit every day since the start of 2013.[Photo by Liu Hui/Asianewsphoto]

Tourists wear masks while visiting Tian'anmen Square as the worst smog in decades continued to rise to dangerous levels in Beijing, on Jan 23, 2013. [Photo by Wang Wenlan/Asianewsphoto]