Beijing’s municipal air pollution emergency response office issued a “yellow alert” for smog on Wednesday, even as a chimney continued to release pollution into the air. Visibility fell to 500 meters (1,640 feet) or less, and the Air Quality Index surpassed 300. Photo: VCG

The Lishui Bridge in Beijing’s Chaoyang district is enveloped in heavy smog on Wednesday. Photo: VCG

Heavy smog shrouds the CMG Headquarters building (center) and other Beijing landmarks in the city’s Central Business District on Tuesday. Photo: VCG

Beijing residents cycle through smog in the city’s Andingmenqiao area on Wednesday. Photo: VCG

A Beijing resident shops at a vegetable market in heavy smog on Wednesday. Photo: VCG

Beijing motorists drive through heavy smog in the city on Wednesday. Photo: VCG