Vietnam Airlines said in the past 24 hours several of its flights were delayed as operations were adjusted to ensure safety.

The carrier noted that during January and February, cold air moving eastward often brings moist air from the sea, leading to thick fog across northern Vietnam that reduces visibility at airports.

“Flights scheduled in the early morning are usually the most affected. Conditions tend to improve from around 11 a.m. onwards, allowing safer take-offs and landings,” a Vietnam Airlines representative said.

Tran Doan Mau, director of the Northern Airports Authority, said four outbound flights were temporarily unable to take off and four inbound flights were diverted as a precaution.

He added that the fog has not yet caused major disruptions to overall flight schedules, noting that peak travel demand around the Lunar New Year and aircraft shortages could also contribute to delays.

Passengers are advised to monitor flight information screens at terminals and stay updated through airlines’ official channels.

The fog episode comes as the capital has experienced heavy haze and elevated air pollution in recent days. Data from air quality monitoring application IQAir showed the city ranked among the world’s most polluted cities on February 5, with an AQI reading of 194, a level considered harmful to health.

Experts said stagnant weather, high humidity and weak winds have trapped pollutants near the ground, while increased traffic and daily activities ahead of the Lunar New Year have added to the burden.

Weather forecasters expect fog and polluted conditions to persist for around three more days before improving as a new cold air mass moves into the northern region.

Air pollution worsens in Hanoi as experts warn of health risks

VOV.VN - Air quality across the capital city of Hanoi deteriorated into poor and unhealthy levels on February 6, with several monitoring stations recording hazardous readings, prompting health warnings from experts and authorities.