It's back: Wave of smog hits Beijing

According to the center's official Weibo account, the index in southeast Beijing reached 141 by 8 am on Sunday. Northwest and northeast Beijing reached almost 130.

Ma Jun, director of the Institute for Public and Environmental Affairs, said this is the first time in three months that Beijing has been hit by large-scale air pollution.

"The smog won't dissolve until Tuesday, and Beijing residents should use protection, such as masks and air purifiers," he said.