On the morning of 9/12, many monitoring stations in Hanoi and hung yen recorded air quality index levels categorized as very unhealthy, with some areas exceeding 240.
After a week of weather-induced improvement, Hanoi's air quality deteriorated to very unhealthy levels on the evening of 7/12, with air quality index (AQI) stations exceeding 200 and fine particulate matter (PM2.5) increasing.
