Haze led to the disruption or cancellation of flights at major airports on Monday and Tuesday.
At Gimpo Airport on Tuesday, 53 domestic flights were cancelled in the morning, and the first international flight did not take off until 10:45 a.m.
"The minimum visual range for take-off is 175 m at Gimpo Airport, but it was a mere 50 m on Tuesday morning," an official with the Korea Airports Corporation said.
A similar low visibility alarm was issued for Incheon International Airport on Monday night, when visibility of the runways dropped to 125-400 m. It was lifted at 11 a.m. Tuesday, delaying 22 flights all day Tuesday and redirecting 18 others to Gimpo and other airports.
A Cebu Pacific Air flight from Manila was supposed to land at Incheon around 8:30 p.m. Monday but landed in Gimpo instead, keeping some 300 passengers in the aircraft for about three hours while Cebu Pacific tried to find a stepladder vehicle.
Across the country, 105 domestic flights were cancelled at Gimpo, Gimhae, Jeju, Ulsan, Yeosu and elsewhere, according to the KAC.
Meanwhile, the toxic haze from China is expected to linger for a sixth day on Wednesday. The concentration of fine particles in the Seoul metropolitan area will reach the dangerous level of 121~200 ㎍/㎥ Wednesday, the National Institute of Environmental Research predicted.
It advised old or weak people to avoid staying outdoors and wear face masks.