However, the air quality monitoring result of AirVisual showed that the AQI air quality index in Hanoi was up to 265 at 6:00 am on September 30; meanwhile, the PM2.5 reached 215.4 micrograms per cubic meter, higher nearly 9 times of the national standard (approximately 25 micrograms per cubic meter) and 20 times of the annual average of the World Health Organization.
According to Assoc. Prof. Dr. Vu Van Giap, General Secretary of Vietnam Respiratory Association, Deputy Director of Respiratory Center of Bach Mai Hospital, when people breathe PM 2.5 dust particles size less than 2.5 micrometers in the lungs, the particles will travel through the bloodstream to organs in the body causing inflammation and disease inflection to many different organs. Therefore, people getting respiratory diseases needed to avoid going out in condition of heavy air pollution.