At around 6 a.m. Monday, only parts of the Nhat Tan Bridge, connecting Tay Ho and Dong Anh districts, could be seen through the smog. Vehicles had to turn on their headlights to see the road.
The Long Bien Bridge, connecting Hoan Kiem and Long Bien districts, was partially obscured by the smog.
Environment experts said smog often appears from October to March next year. The causes included the lack of rain, thick fogs and poorly managed emissions, preventing pollutants from being dissipated and causing them to be concentrated on lower levels.
Skyscrapers in Nam Tu Liem District could not be seen clearly due to the smog. The peak of the Keangnam Tower, 350 m high, was totally obscured.
A full aerial view of Ring Road 3 was obscured by clouds and smog. Several air quality stations in the city showed Air Quality Index (AQI) levels as either very poor or dangerous.
For example, a station on Nguyen Van Cu Street, Long Bien District, managed by the Pollution Control Department, showed an AQI level on November 28 at 225, considered as very poor air quality that would affect everyone.
Among 16 air quality stations of the Hanoi Department of Natural Resources and the Environment, thye station on Pham Van Dong Street, Bac Tu Liem District recorded the highest AQI levels at 194, close to "very poor" air quality.
People wore face masks as they exercised at around 6:30 a.m. on Monday at the Xa La urban area in Ha Dong District.
At 7:55 a.m., AQI levels recorded at a station in Thanh Xuan District was at 134. Tay Ho and Long Bien districts suffered the most pollution, with AQI levels reaching 158, and people were recommended not to go out.
At around 9 p.m. on Sunday, people in traffic on Nguyen Trai Street, Ha Dong District had to turn on headlights to see the road through the smog.
Due to heightened levels of AQI, the Switzerland-based air quality monitoring facility IQAir AirVisual ranked Hanoi as the fourth most polluted city in the world.
Environmental agencies said Hanoi's pollution stemmed from traffic emissions. The capital has around 7.8 million vehicles, including over 1 million cars, over 6.6 million motorbikes and over 184,000 electric motorbikes. There are also around 1.2 million more vehicles coming to the capital from other localities.
Emissions from industrial activities and trash incineration also contribute to pollution. In the picture, colums of smokes can be seen coming off from the Van Dien Fused Magnesium Phosphate Fertilizer company in Thanh Tri District.
Dusts coming off construction sites in Hanoi also contribute to air pollution. In the summer, when it rains frequently, dusts are not as rampant as they are during the winter.
In the picture, an ongoing construction site of a traffic project worth VND1.2 trillion ($49.47 million) in Long Bien District can be seen.
Hanoi is covered by smog and fine dusts. Video by VnExpress/Ngoc Thanh