With the colder temperatures,... air pollution levels are skyrocketing in China,... as hundreds of millions of people start cranking up the heat.
Beijing and parts of China are blanketed in a thick layer of smog,... leading to the government issuing a yellow alert.
Lee Seung-jae reports.
The Beijing Municipal air pollution emergency response office on Tuesday issued a yellow alert for smog.
Under Beijing's three-tier warning system, the yellow alert is the least severe, followed by orange and red.
However, a yellow alert still triggers a series of compulsory emergency responses, including the suspension of outdoor construction operations to reduce dust, the restriction of heavy pollution vehicles, or the suspension of production in smokestack industries.
The pollution is expected to persist throughout the week,... affecting other parts of China, such as Tianjin and the Hebei regions,... which are forecast to see moderate to severe air pollution until Thursday.

"Everytime there's smog, my throat hurts, phlegm continues to build and my nose hurts, too. There's nothing I can do at the moment."

Environment officials in China say the build up of smog is due to high humidity and weak winds,... leading to poor air diffusion.
But others say, with the heating system activated last week,... this, too, is the source of much of the pollution.
The good news is that,... with cold air and rain expected from the Northern region of China on Thursday.... the smog is forecast to decrease, as well.
Lee Seung-jae, Arirang News.