Most cities saw the 24-hour average levels of dangerous PM2.5, particles that are less than 2.5 microns in diameter, within the Vietnamese standards.

The number of days with good and moderate air quality in May was also higher than in previous months.

The data was aggregated from 18 monitoring stations in Hanoi, Viet Tri, Ha Long, Hue, Da Nang, Nha Trang and Ho Chi Minh City.

Hanoi, which is usually more seriously polluted with particulate matter than other cities, had 90% of days with moderate to good air quality.

The PM2.5 levels monitored at most stations in the city centre were within Vietnamese standards, but the concentration of the fine particulate matter reached dangerous territory in Pham Van Dong, Hang Dau and Minh Khai Streets on several days.

According to the Vietnam Environment Agency, May marks the beginning of the rainy season, so the air quality in many localities, especially Hanoi and northern provinces, is better than in the dry season months.

However, the national weather agency has warned that prolonged heatwaves in summer can affect the air quality considerably, especially in urban areas. Nhan Dan

Ministry looks at ways to improve air quality

Deputy Minister of Natural Resources and Environment Vo Tuan Nhan has called for sources of severe air pollution to be identified a soon as possible.

Air quality in most urban areas good in first half of May

The air quality of many urban areas across Vietnam remained good in the first half of May.