BEIJING: Chinese cities are limiting the number of cars on roads and have temporarily shut down factories to cut down pollution during a national "red alert" for smog.

State media reported Monday that more than 700 companies stopped production in Beijing, and that traffic police were restricting drivers by monitoring their license plate numbers. Dozens of cities closed schools and took other emergency measures after a "red alert" was issued from Friday night to Wednesday for much of northern China.

Authorities in northern Hebei province ordered coal and cement plants to temporarily shut down or reduce production. Elsewhere, hospitals prepared teams of doctors to handle an expected surge in cases of pollution-related illnesses.

China's long-standing air pollution is blamed on its reliance on coal and emissions from older cars.