If they are forced to go into school for any special reason, then schoolchildren should avoid outdoor activities.

The ministry also advised people to regularly monitor air quality, noting an air quality index of over 100 is considered bad, and people with respiratory and heart diseases are advised to stay home. If the index increases to over 150, then all residents are affected.

Air pollution in Vietnam is typically caused by fine dust with a diametre of less than 2.5 micrometres, specifically known as PM2.5, which is particulate matter that can be found in the air. When inhaled, they penetrate directly into the bloodstream and travel to important internal organs.

Direct contact with PM2.5 can lead to serious respiratory, cardiovascular, and neurological diseases. A PM2.5 pollution index of 12 microgrammes per cubic metre is widely considered to be at a safe level. This index is equivalent to AQI level 50.

Health experts say people should try to limit opening windows and doors when the air is polluted. In addition, regularly cleaning rooms and houses and planting trees around the house can help prevent dust and clean the air.

People also should clean their noses, gargle physiological saline in the morning and evening, especially after going out, and wash their eyes with physiological saline at night before going to bed.

Source: VOV