Air quality in the capital has once again worsened to dangerous levels after it previously improved for a short period of time.

Vietnam is considered the most polluted country in the world, above the likes of Chile, China, and Indonesia. 

The air quality index (AQI) in Hanoi at 6:13 on July 28 morning was recorded at the hazardous level of 293, exceeding the red-warning level, following an evaluation of air quality through the monitoring application PAMAir. The latest recordings reached purple level, meaning that the air quality can be judged to be very unhealthy for humans.

Elsewhere, AirVisual, a Swiss-based air quality monitoring facility that specialises in generating data from public, ground-based, and real-time monitoring stations, recorded Hanoi's AQI level at 172 at 7:47 on July 28. This result means that Vietnam can be considered the most polluted country in the world, above the likes of Chile, China, and Indonesia.

Moreover, the AQI in northern provinces, including Ninh Binh, Nam Dinh, Bac Ninh, and Hai Duong, remained at red level, with the index reaching 180 in some locations.

The AQI is a metric used by multiple Government agencies in an effort to determine how polluted the air is locally. It is widely thought that an AQI level above 100 can be considered polluted and therefore unhealthy for humans, while children and individuals suffering from respiratory and heart diseases are advised to stay home and avoid outdoor activities when AQI levels reach 150 or above.

Hoang Duong Tung, president of the Vietnam Clean Air Partnership, said air quality in Hanoi has begun to worsen since July 27, with the July 28 morning seeing the local air quality become extremely bad between 4 a.m. and 5 a.m.

“This is quite rare situation when Hanoi is in the middle of summer”, he stressed, adding that the initial results could be due to changes in weather, particularly in terms of temperature and wind patterns, factors which have caused large amounts of dust to remain.

Tung recommended that adults, children, pregnant women, and people suffering from respiratory diseases should wear masks and glasses when going outside.