Unhealthy smog hovered over downtown Beijing as limits on cars, factories and construction sites kept pollution from spiking even higher Wednesday, on the second of three days of restrictions triggered by the city's first red alert for smog.

Cars with even-numbered license plates were kept off roads, and schools and constructions sites remained closed. Far fewer than usual pedestrians walked the streets — many of them wearing white masks to filter the air.

Insurance and water purifier saleswoman Zhang Jingtie said she had no choice but to be out despite restrictions through 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 Zhang, 25. "So, we really need to do something to protect the environment."

Pollution levels midday 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 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 meter downtown — or 8 to 10 times the safe level recommended by the World Health Organization.

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 of smog has triggered its first red alert under a 2-year-old system of alerts and restrictions to deal with persistent contamination.

A grey soupy haze subsumed Beijing's unique landmarks, convenience stores sold air-filtering masks at brisk rates and health-food stores promoted pear juice as a traditional Chinese tonic for the lungs.

"And air purifiers at home are a must," Beijing resident Sun Yuanyuan said at a downtown Beijing juice shop.

A slew of Beijingers said via social media they planned to escape the gloom. They needed to travel relatively far, because nearly all of China's northeast was affected, and some cities — including nearby Shijiazhuang — were even worse than Beijing.

After hearing of the school closings late Monday, Beijing mother Jiang Xia booked tickets for a 3,200 kilometer (2,000-mile) flight to the relatively clean southwestern city of Kunming, for herself and her 8-year-old daughter who she said suffers nosebleeds in the smog. She said in an interview from Kunming that they hectically packed before dawn Tuesday for their flight.

"But when we arrived in Kunming and breathed in this clean, fresh air, I was very glad I made this move — a very wise decision," Jiang said.

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.