The famed Long Biên Bridge enveloped in a hazy smog caused by air pollution. VNA/VNS Photo Hoàng Hiếu

HÀ NỘI — Hà Nội has once again topped the list of the world’s most air-polluted cities, with air quality reaching the purple level, classified as 'Very Unhealthy' as recorded on Tuesday morning.

According to the IQAir air monitoring system, at 8.04am on Tuesday, Hà Nội's Air Quality Index (AQI) was recorded at 272.

Another Vietnamese city HCM City, also ranked among the top five most polluted cities in the world at the same time, with an AQI of 186, classified as 'Unhealthy'.

These figures can vary depending on the time and time zone, as cities worldwide enter their respective rush hours, during which traffic and industrial activity peak.

In Việt Nam, according to VN Air, an air quality monitoring app developed by the Ministry of Natural Resources and Environment, the most polluted area nationwide as of 8am was the 708 Market area in Mỏ Chè Ward, Sông Công City in the northern province of Thái Nguyên, where air quality was categorised as very poor.

Hà Nội street shrouded in smog and fine dust.

In Hà Nội, air quality readings from two VN Air monitoring stations were consistent with the AQI results, both at the purple level, with indices of 226 and 216. These readings were taken from the Giải Phóng Street and Nguyễn Văn Cừ Street areas, major gateways to the city centre that experience heavy traffic during rush hours.

In HCM City, two monitoring stations reported air quality at the orange level, categorised as 'Poor'.

According to VN Air, the best air quality nationwide as of 8am on Tuesday was recorded at the Diên Phú station in Gia Lai, with an AQI of 12, classified as 'Good'. The next best area was Đông Tân-Hữu Lũng in Lạng Sơn Province, with an AQI of 13.

From January 8 to 9, air pollution is expected to persist, but decrease in severity. Between January 10 and 12, the northern region may experience improved air quality, more favourable for outdoor activities and gatherings.

This improvement is attributed to the influence of a northeast monsoon, with air quality reaching the yellow level, suitable for outdoor activities and events. However, heavy air pollution could return to the northern region early next week. — VNS