BEIJING, Dec. 21 (Xinhua) -- Beijing will lift its red alert for air pollution after Wednesday night as cold air is expected to disperse the smog that has lasted for several days.

The red alert, which has been in force since Friday evening, will be lifted at 12 a.m. Thursday, said the city's heavy pollution emergency response headquarters on Wednesday afternoon. Air quality will improve remarkably after midday Thursday in Beijing.

Emergency measures such as car restrictions based on even-odd license plate numbers will end, and kindergartens and schools will resume classes.

The PM2.5 density in the capital remained at high levels on Wednesday.

More than 20 cities in north China issued red alerts for the latest bout of polluted air. Hundreds of flights were disrupted and many freeways closed due to low visibility in some affected areas.