Beijing pollution levels have soared to the worst in months on Thursday (January 16), reaching hazardous levels.

Morning traffic was shrouded in thick smog. Four highways had to be closed.

Commuters wore masks, fearing they could get sick.

(SOUNDBITE) (Mandarin) 25-YEAR-OLD TV PRODUCER MI XI SAYING:

"For instance, personally I have nasal inflammation, and today it's really bad. Often I worry that the air pollution is harming me."

Heavy pollution has taken its toll on Beijing residents.

(SOUNDBITE) (Mandarin) DOCTOR LAN WENXIAN SAYING:

"The pollution is really bad. Recently I have had a bad cold all the time, have difficulty breathing and the phlegm that I cough up is black. I'm planning to leave Beijing. I don't want to stay here."

Authorities will begin imposing limits on car traffic, construction and manufacturing if three consecutive days of hazardous pollution are forecast.

To curb pollution, the city will also start using gas i