Hanoi air quality returns to very unhealthy levels

At 8 a.m. the Air Quality Index (AQI) at the monitoring station outside the Hanoi University of Science and Technology on Giai Phong Street reached 228, or "very unhealthy." It had entered this range as early as 3 a.m.

The AQI was 182 (unhealthy) at the station at Nhan Chinh Park on Khuat Duy Tien Street and 177 at the Nguyen Van Cu Street facility.

At 11:30 a.m. Swiss air quality technology company IQAir ranked Hanoi the fourth most polluted city in the world with an overall AQI of 193, behind only Kolkata and Delhi in India at 220 and 211 and Baghdad, Iraq (196).

It also showed dozens of locations in Hanoi with "very unhealthy" air, including Thanh Xuan, Minh Khai, Vinh Tuy, Ha Dong, and Tay Ho.

Hanoi was at moderate to poor levels for many days as repeated cold-air surges created favorable conditions for dust dispersion, but since Thursday, as the cold air stabilized and large day–night temperature differences caused a temperature inversion, pollution levels have begun to rise.

The current pollution is mainly caused by fine particulate matter PM2.5.

According to IQAir, PM2.5 concentration in Hanoi this morning was at 142.7 ug/m3 , which is 28.5 times the World Health Organization safe value.

Near Hanoi, very unhealthy air quality has also been recorded in Hung Yen Province with an AQI of 214 on Nguyen Van Linh Street and 215 at Thai Binh Bridge.

Several other places have also reported high pollution, including Thai Nguyen Province and Hai Phong City.

The Ministry of Agriculture and Environment’s department of environment expects air quality in Hanoi to remain "very unhealthy" Saturday.

The air quality forecasting system at the Vietnam National University, Hanoi, said an air pollution episode lasting until Jan. 14 has started and would peak on Jan. 11.

Vu Huu Liem, director of the Center for Agricultural, Natural Resources and Environment Monitoring under the National Telecommunications Administration of Ministry of Agriculture and Environment, said high-resolution and ultra-high-resolution satellite imagery are used to monitor pollution hotspots.

This allows comprehensive coverage of the entire city, monitoring construction areas and craft villages, and detecting emission signs such as smokestacks and open burning sites.

The center also uses the Matrice 300 RTK unmanned aerial vehicle to conduct detailed monitoring and handle emerging situations in real time.

The drone helps capture close-up images at hotspots where garbage and straw are burned or there are other localized emissions, enabling inspection and enforcement.

Authorities have identified 68 construction sites and 14 plastic and steel recycling villages that require priority monitoring.

Construction sites are sources of dust pollution if they are not properly covered in accordance with regulations.