The air quality index (AQI) in the capital city measured at nine monitoring stations throughout the city ranged from 36 to 66.
At monitoring stations such as My Dinh, Pham Van Dong, Thanh Cong, and Hang Dau, the AQI was recorded at an average level of 58, 63, 65, and 66, respectively.
Furthermore, the AQI in in Hoan Kiem, Tan Mai, Tay Mo, and Kim Lien was also at a good level.
According to environmental experts, Hanoi's air quality has returned to a good level thanks to a recent spell of powerful cold air mass coupled with heavy rains. This has dissolved and dispersed temperature inversions and blankets of polluted air mass, thereby cleaning the amount of dust within the atmosphere.
They also recommended that local residents follow air quality information before going out to protect their health.
Earlier on October 27 the air quality in Hanoi worsened, ranking third among the world's most polluted cities, only behind India and Pakistan.
The primary factors behind the worsening pollution levels are heavy congestion, large-scale construction, and straw burning.