Fog drapes over Ho Chi Minh City

A layer of fog can be seen surrounding neighborhoods, as seen from the Landmark 81, Vietnam's tallest building.

Le Dinh quyet, head of the weather forecast division of the Southern Regional Hydro-Meteorological Center, said the fog was formed due to cold air and low-altitude clouds. The fact that the city has many skyscrapers, which block the winds, also causes the fog to be dissipated more slowly.

From the Thanh Da Canal Bridge, the Landmark 81 building could not be seen due to the fog, despite being only a kilometer away.

The Binh Loi Bridge, connecting Binh Thanh District and Thu Duc City, was obscured by the fog.

Workers check the status of a railway of HCMC's first metro line at the Thao Dien Station section.

The fog also reduced vision range of vehicles in traffic on Dien Bien Phu Street, forcing many to turn on headlights.

Le Thi Xuan Lan, a weather expert, said the fog is the result of low-temperature air and how sunlight interacted with emission and particulate matter in the atmosphere.

These factors made the fog in HCMC last from morning until noon, causing air pollution, Lan said.

HCMC's air quality index as of Tuesday night is at 172, classified as unhealthy, according to air quality monitoring website IQAir.

By 11 a.m., the fog slowly dissipated, but the sky was still gloomy due to the lack of sunlight.

Temperatures in HCMC were at around 23-24 degrees Celsius in the early morning.

Truong Thi Anh Kim and her friends posed for photos outside of the Diamond Plaza in District 1, which is now full of Christmas decorations.

People travel under the canopies on Nguyen Binh Khiem Street, District 1 at noon, without the usual strong sunlight.

Le Dinh Quyet said foggy weather would persist in HCMC over the coming days due to cold air coming fown from the north. Temperatures in the southern metropolis may drop to 21-23 degrees on Christmas Day.