At 8:00 AM on 4/3, all three Hanoi air quality monitoring stations operated by the Department of Environment (Ministry of Agriculture and Environment) reported very good AQI levels. The station near the entrance of Hanoi University of Science and Technology on Giai Phong street, which typically shows the highest pollution, currently registered an AQI of 33. The station at 556 Nguyen Van Cu recorded an index of 49, while the Nhan Chinh park station on Khuat Duy Tien street registered 36. A few days prior, Hanoi's AQI had fluctuated between moderate and poor.

Good air quality was also observed across most northern provinces and cities: Phu Tho recorded an AQI of 29, Bac Giang 44, Ha Nam 44, and Thai Nguyen 34.

The northeasterly monsoon contributes to improved AQI in Hanoi. *Photo: Giang Huy*

Currently, IQAir, a platform specializing in ranking global city air quality, indicates that Hanoi is not among the top 100 most polluted cities. Dozens of monitoring stations across the system also display moderate air quality, corresponding to an AQI of 51-100.

Despite unchanged stationary emission sources from traffic, construction, and industry, the improved AQI in Hanoi and the northern region is primarily attributed to the arrival of the northeasterly monsoon. Last night, the monsoon brought rain, facilitating the dispersion of pollutants.

AQI value conversion chart. *Graphic: Dang Hieu*

The Department of Environment forecasts that Hanoi's air quality will remain good today; however, pollution levels will gradually increase tonight as the northeasterly monsoon weakens. Tomorrow, Hanoi's AQI is expected to return to poor levels. Conversely, an air quality project forecast by the University of Engineering and Technology, Vietnam National University, Hanoi, predicts good air quality in Hanoi until 6/4.

Gia Chinh