A worker sits by a billboard depicting the Central Business District under construction in Beijing, China, Monday, Jan. 16, 2017. The International Monetary Fund on Monday raised its growth forecast for China but warned rising debt that has prompted … Workers pause at the construction site of the Central Business District in Beijing, China, Monday, Jan. 16, 2017.

A security guard wears a mask during duty in Beijing, China, Saturday, Dec. 17, 2016. China’s capital and other northern cities have banned half of all vehicles from city streets and ordered factories, schools and construction sites closed in … A woman adjusts her mask before walking outdoors in Beijing, China, Saturday, Dec. 17, 2016.