Unhealthy smog returns to Hanoi as stagnant weather traps PM2.5
Hanoi woke up to another heavy smog episode on Nov. 17, as all three national air-quality monitoring stations reported « unhealthy » pollution levels across the capital.
Between 8:00 and 8:15 a.m., air quality index (AQI) readings ranged from 151 to 173, high enough to pose serious health risks for sensitive groups.
AQI readings between 151-200 indicate « unhealthy » air pollution.
The Parabol Gate station at Hanoi University of Science and Technology on Giai Phong Street showed an AQI of 173, while Khuat Duy Tien Park in Nhan Chinh measured 151. A third station at 556 Nguyen Van Cu recorded 156. The key pollutant was PM2.5, the fine particulate dust linked to respiratory and cardiovascular problems.
Air quality began deteriorating a day earlier as weather conditions, light winds and temperature inversion, trapped pollution near the ground. Hanoi’s own monitoring portal, which now displays data from only four stations, showed three matching the national readings. A fourth station, at 46 Luu Quang Vu Street, measured « poor » conditions. In previous years, the capital’s network typically showed 20–30 active stations.
Global tracking site IQAir ranked Hanoi the world’s fifth most polluted city on Monday morning, behind cities in India, Pakistan and Uzbekistan.
While Hanoi struggled with thick smog, surrounding provinces did not see the same spike. Stations in Tien Son Industrial Park in Bac Ninh Province and Tan Quang in Hung Yen reported AQI levels below 50, considered « good. » Stations in Gia Binh, Tu Son and Thuan Thanh in Bac Ninh and Viet Tri in Phu Tho registered « moderate » air quality.
Environmental officials said the capital is entering its peak pollution season, lasting from November to April, driven by traffic, construction, industry, household emissions and stagnant weather patterns.
Hanoi is rolling out several measures to curb pollution, including phasing out gasoline motorbikes inside Ring Road 1 in the downtown area from July 2026, extending the restriction to Ring Road 2 in 2028 and to the outlying Ring Road 3 in 2030.
National agencies are also drafting new emission standards for cars, motorcycles and mopeds. Under the latest proposal, Hanoi and Ho Chi Minh City would begin emissions inspections on July 1, 2027, expand this to other centrally governed cities a year later, and apply nationwide by 2030.
By Gia Chinh – VnExpress.net – November 16, 2025