JINAN, Feb. 15  -- Heavy smog delayed more than 50 flights on Sunday at an airport in east China's Shandong Province, stranding travelers on their way home for the Chinese Lunar New Year holiday.

The provincial capital Jinan was blanked by heavy pollution, with an Air Quality Index (AQI) reading of 285 at 4 p.m., according to the China National Environment Monitoring Center.

"It was a gloomy and humid morning," said Zheng Yue, a resident of Jinan. "By the afternoon, the sky was even darker."

The air quality disrupted a third of Jinan International Airport's takeoffs and landings on Sunday.

The airport said that as of 6 p.m., at least 55 flights were delayed, including 23 arrivals and 32 departures.

Flights to Shenyang, capital of northeast China's Liaoning Province, and to Haikou, in the southern province of Hainan, were delayed by more than four hours.

Jinan Airport is a pivotal hub in east China, which serves both domestic and international flights.