Dense mist in Hanoi
According to the Vietnam Environment Administration, the mist appeared because temperatures increased after some cold days. Humidity and drastic changes between day and night temperatures are the cause of the mist. At midnight and early morning, there was no wind and pollutants were trapped because of temperature inversion.
The Environment Protection Department, under the Hanoi Department of Natural Resources and Environment, said the current air quality was harmful to the elderly, children and those with respiratory illnesses.
Citizens are advised to stay indoors and use face masks when going out.
