Smog lowered visibility to less than 50 meters in parts of northeast China, leading to the weekend closure of highways and an airport. Seven expressways were partly or wholly shut on Sunday, according to the transport authority in Liaoning Province. Farther north in Heilongjiang Province, more roads and an airport shut on Saturday, including Taiping International Airport in Harbin city, which canceled all 209 inbound and outbound flights. The airport said that flights were operating again on Sunday as visibility improved. China’s national meteorological center said a cold front and rain approaching from the west would gradually reduce the haze.—AP