A couple wearing protective masks poses for a self portrait in thick haze on Tiananmen Square in Beijing Tuesday, Jan. 29, 2013. Extremely high pollution levels shrouded eastern China f

 

              A couple wearing protective masks poses for a self portrait in thick haze on Tiananmen Square in Beijing Tuesday, Jan. 29, 2013. Extremely high pollution levels shrouded eastern China f
A couple wearing protective masks poses for a self portrait in thick haze on Tiananmen Square in Beijing Tuesday, Jan. 29, 2013. Extremely high pollution levels shrouded eastern China for the second time in about two weeks Tuesday, forcing airlines in Beijing and elsewhere to cancel flights because of poor visibility and prompting government warnings for residents to stay indoors. (AP Photo/Ng Han Guan)