Hanoi has been enveloped in toxic smog for more than a week, with PM2.5 levels far above WHO guidelines and the city ranked second-most polluted globally on IQAir. Authorities have ordered limits on outdoor activity, possible school closures, and measures to curb illegal burning and construction dust, but journalists report weak enforcement. Experts blame construction, vehicle emissions, coal plants and agricultural burning. A planned ban on gasoline motorbikes in central Hanoi during certain hours is due to begin in July next year.
Hanoi Choked by Toxic Smog: Air Quality Ranks Second-Worst Worldwide
Vehicles drive on a highway during heavy air pollution in Hanoi on December 11, 2025 (NHAC NGUYEN)(NHAC NGUYEN/AFP/AFP)
Toxic smog has blanketed Vietnam's capital for more than a week, obscuring the skyline and leaving residents coughing and wheezing as Hanoi's air quality plunged to among the worst in the world.
Rapid Deterioration and Measurements
The city of about nine million was ranked second only to New Delhi on IQAir's list of the world's most polluted cities on Thursday morning, with a slight improvement by the afternoon. IQAir reported that concentrations of PM2.5 — microscopic particles that can penetrate the lungs and enter the bloodstream and are linked to cancer and other serious illnesses — far exceeded the World Health Organization's recommended daily exposure limits.
Residents Speak Out
"I have experienced difficulty in breathing out on the streets these days," said resident Dang Thuy, who told AFP she purchased two new air purifiers for her apartment.
Many residents reported masking up, staying indoors when possible, and expressing frustration that everyday activities have become uncomfortable and unhealthy.
Official Response and Enforcement Gaps
Hanoi authorities issued an administrative order urging people to limit time outdoors and warning that schools may be closed if conditions worsen. Officials were instructed to crack down on illegal waste burning and reduce dust from construction sites by covering trucks and spraying water.
However, AFP journalists observed construction sites operating normally, with trucks arriving and departing uncovered. Reporters also saw people burning household rubbish along the Day River on the city's western outskirts, highlighting enforcement shortfalls.
Why Pollution Is So High
Experts point to several contributing factors: extensive construction activity across the city, emissions from the large number of motorbikes and cars, smoke from agricultural burning, and emissions from coal-fired power plants to the north. The combination of these sources has driven PM2.5 levels well above safe thresholds.
Health Risks and Practical Advice
The World Health Organization links long- and short-term exposure to air pollution with strokes, heart disease, lung cancer and respiratory infections. Authorities and health experts recommend that vulnerable people — including children, the elderly and those with preexisting conditions — avoid outdoor exertion, use N95/FFP2 masks when necessary, and consider indoor air purifiers where possible.
Planned Measures
Officials have announced plans to ban gasoline-powered motorbikes from central Hanoi during certain hours starting in July next year as part of broader efforts to curb urban emissions. Observers say stronger enforcement of existing rules, rapid reduction of illegal burning and stricter construction dust controls are urgently needed to bring air quality down to safer levels.
Note: Residents should follow local advisories for updates on school closures and outdoor activity restrictions.
