The air quality index (AQI) taken from 10 different air monitoring stations in Hanoi from February 11-12 showed air quality at a bad level, according to the Hanoi Environment Protection Sub-department.

Workers came back to the city after the Tet, or Lunar New Year holiday, making air quality worse. (Photo: laodong.vn)

The index was between 103 and 131, meaning the air quality in all monitored areas was poor.

Specifically, the index in Trung Yen was 109, in Minh Khai-Bac Tu Liem was 129 and Hoan Kiem was 105. It remains 131 in Hang Dau and 105 in Kim Lien.

A number above 150 is unhealthy for anyone, while anything between 201 and 300 is very unhealthy, according to the US Environment Protection Agency.

Weather conditions in recent days, with dry and cold air and a lack of rain and wind, have been blamed for the poor weather. These conditions meant pollution cannot diffuse.

Moreover, workers returned to the city after the Tet, or Lunar New Year holiday, putting more vehicles travel on the roads.

Earlier during the last days of last month, air pollution in Hanoi was also measured at the severe level that health experts have warned people to stay indoors.

According to Dr Hoang Duong Tung, head of the Vietnam Environment Administration, the deterioration of air quality in Hanoi is due to the increase in traffic as the Tet (Lunar New Year) holiday approaching. 

He advised people to monitor air quality regularly through the Hanoi City portal (hanoi.gov.vn) or network of the Environment Administration or the US Embassy.-VNA