Smog hovered over Beijing as limits on cars, factories and construction remained in force after the city imposed its first red alert for air pollution.
Cars with even-numbered licence plates were kept off roads, and schools and building sites stayed closed on the second of three days of restrictions triggered by the alert.
Far fewer than usual pedestrians walked the streets - many of them wearing white masks to filter the air.
Pollution levels at midday on Wednesday in downtown Beijing were mostly between 250 and 300 on the city's air quality index - suggesting the restrictions were having an effect.
The city's alert was triggered by a forecast on Monday that pollution levels would be above 300 for three days straight.
The index is strongly linked to levels of the dangerous tiny particles PM2.5, which at midday ranged from about 200 to 250 micrograms per cubic metre in the downtown area - eight to 10 times the safe level recommended by the World Health Organisation (WHO).
Insurance and water purifier saleswoman Zhang Jingtie said she had no choice but to be out despite restrictions through to Thursday that have prompted some businesses to close and some others to allow employees to work from home.
"I stay outdoors most of the time, so I am very worried that I may have cancer if I continue to live in this kind of air for long time," said Ms Zhang, 25. "So, we really need to do something to protect the environment."
Although many other cities in China and elsewhere in the world typically see levels of smog even worse than Wednesday's pollution in Beijing, the Chinese capital's latest bout has triggered its first red alert under a two-year-old system of alerts and restrictions to deal with persistent contamination.
The capital's hazardous smog has persisted despite the Chinese government's stated priority of cleaning up the legacy of pollution left from years of full-tilt economic growth.
Most of the smog is blamed on coal-fired power plants, along with vehicle emissions, construction and factory work.