Vehicles drive on a smoggy day in Tianjin, Oct 6, 2013. [Photo/Xinhua]

BEIJING - Heavy fog that shrouded most parts of north China Sunday has closed down expressways and several airports, hindering the return of holiday travelers towards the end of the golden week.

In Beijing, heavy smog lasted into the second day Sunday and visibility was under 1,000 meters in the downtown areas.

As of 10 a.m., traffic police authorities had closed down six interprovincial expressways, including roads linking the capital with Harbin in the northeast, Shanghai in the east, as well as Tianjin and Hebei Province.

Beijing's Capital International Airport reported even lower visibility Sunday morning, averaging 250 to 500 meters.

Despite the foggy weather, airport authorities said 159 departing flights had taken off as of 9:30 a.m., accounting for 56 percent of the total planned takeoffs. Thirteen flights had been canceled.

Poor visibility at the airport caused 29 incoming flights to land at airports in neighboring cities and forced another five to return.

Meanwhile, authorities in Tianjin said they had closed down all 14 expressways in the northern municipality amid heavy fog.

In the neighboring Hebei Province, 13 expressways have been closed until visibility improves.

Foggy weather has also affected most parts of Liaoning Province. As of Sunday morning, 15 expressways have been closed down.

In the foggiest industrial city of Anshan, visibility was under 50 meters in some areas and many travelers were forced to postpone their trips.

Sunday is the sixth day of the week-long holiday for China's National Day and large crowds of holidaymakers are heading home from their tours.

The foggy weather has wreaked more havoc on the road, as expressways, that open for free during the holiday, are already under heavy pressure.