By 7 a.m., visibility along major roads such as Le Van Luong, To Huu, Lang Ha, Hoang Cau and Nga Tu So was severely limited. High-rise buildings were obscured by the haze, visible only as indistinct shapes.
Along Le Van Luong Street, 20–30 story apartment blocks on both sides of the road were barely visible above the 10th floor. Despite daylight conditions, cars and motorbikes were forced to switch on fog lights to move safely.
Environmental experts indicated that the phenomenon has resulted from a dual effect of intensified cold air compressing a low-pressure trough and high humidity caused by light drizzle, forming a thick layer of fog.
They noted that the fog was not just moisture but also contained fine particulate matter (PM2.5) trapped near the ground by prolonged temperature inversion.
Light rain and high humidity caused pollutants, making conditions uncomfortable for people traveling outdoors.
As air quality remains poor and the weather turns colder with rain, health experts recommend that residents, particularly the elderly and young children, avoid going out early in the morning. Commuters were urged to wear fine-dust masks, stay warm, and proceed cautiously due to reduced visibility.
