Following a rain on Wednesday morning, Hanoi's air quality index (AQI) has fallen from over 200 (very poor air quality) on Tuesday afternoon to 100 in the morning.
Certain areas with higher AQI may pose impacts to the health of children, the elderly and those with cardiovascular and respiratory diseases.
On Tuesday afternoon, Hanoi was the most polluted city in the world with a general AQI at 198, according to statistics from over 30,000 air quality survey stations around the world.
At around 8 a.m., the Long Bien bridge area could be seen covered in fog. Hanoi's temperature on Wednesday is around 18 degrees Celsius on average, and the figure will fall gradually towards the weekends as a mass of cold air arrive in the north starting Wednesday night.
Chuong Duong bridge is also similarly covered in fog, making it difficult for vehicles to observe objects in faraway distances.
Waterway vessels travel on the Red River.
On Wednesday, air quality survey stations revealed Hanoi's spots with the worst air quality were on Nguyen Van Cu Street with an AQI of 202, and on Giai Phong Street with an AQI at 223.
People walk around the Hoan Kiem Lake.
Hanoi may record light drizzles on Wednesday as temperatures fall, according to the National Center for Hydro-Meteorological Forecasting. Hanoi's temperatures during the cold period would be around 15-17 degrees.
The upper part of a skyscraper on Dao Tan Street is obscured by fog.
The first major cold wave of the year is set to plunge temperatures in the plains down to around 14 degrees, and down to 5 degrees on the mountains from Wednesday night.
Fog drapes over several buildings on Phan Chu Trinh Street. On Wednesday morning, AQI levels in the area reached 74, signaling average air quality levels.
Fog obscures vision over an elevated section of Ring Road 3.
Hanoi has around 8.2 million vehicles, including 1.2 million cars and 7 million motorbikes. Traffic accounts for 56% of road dust emission, one of the five main sources of air pollution in the city.
PM2.5 levels in Hanoi ranged between 26-52μg/Nm3 in the 2022-2023 period, around 1.1-2.1 times higher than the national standards.
