The Division of Environment Protection of Ha Noi yesterday informed that the air quality index (AQI) in the capital city has mostly been moderate condition (yellow alert) and unhealthy for sensitive groups with orange alert, even unhealthy level as dust concentrations in air tend to be higher at nighttime and early morning of the two recent days.
The bad atmosphere condition was due to differential temperatures of up to 9- 10 degrees Celsius between daytime and nighttime causing deep clouds and high concentration of air pollutants near the ground.
