China's largest mobile-based car-hailing company, Didi Kuaidi, said that since traffic controls were launched on Monday night in Beijing, the number of appointments for private cars has nearly doubled.

In addition, calls for regular taxis increased by about 80 percent in the morning peak hours, the company said.

Wang Rui, 27, who works as a clerk at a media company, said that it was more difficult to call a private car through the car-hailing app during peak hours, as Beijing saw its first red alert for air pollution on Tuesday.

"Before, I just needed to wait a few seconds until drivers scrambled for my order, but today I waited about two minutes," she said, adding that the fare was more than double the regular price.

"I spent 35 yuan ($5.50) for the trip from my home to the office, but usually I only spend 16 yuan," she said.

However, she added, "the traffic is very smooth. I spent less time on the road－only about 15 minutes."

Beijing issued its highest-ever air pollution alert on Monday. It will last from 7 am on Tuesday to midnight on Thursday.

Under a red alert, cars are allowed on the roads on alternating days depending on odd or even license plate numbers. Electric vehicles are not limited, according to the city's emergency management headquarters.

In addition, the number of government vehicles used for public services will be cut by 30 percent, and heavy trucks are barred.

Li Peng, a Didi driver, said, "The number of passengers has risen by 60 percent. I usually fulfill five orders on average during the peak hour from 6 am to 10 am each day, but today I fulfilled eight orders."

Moreover, Li said, he usually needs to wait five to 10 minutes to receive an order from the next passenger, but on Tuesday "the orders were continuous. Once I finish the last order, the next order arrives immediately. Furthermore, I can drive faster because there are fewer vehicles on the road."

Schools and kindergartens were to be closed during the red alert, and enterprises were encouraged to adopt flexible work schedules for staff, which can relieve traffic pressure.

Car-hailing companies are expanding their private-car services to electric cars to cut air pollution from auto emissions.

On Monday, Uber launched an electric car service in 13 cities, including Beijing, Shanghai and Guangzhou. In Beijing, Uber passengers choosing electric car service will get a 60 percent discount.

Meng Jing and Ma Si contributed to this story.