Air quality in Hanoi sharply declined on the morning of 27/1, as a weakening cold front created unfavorable meteorological conditions for dust dispersion.
Nighttime temperature inversion elevates fine dust concentrations, which, combined with freezing weather, constricts blood vessels, putting residents at a "pincer" risk of stroke and myocardial infarction.
On the morning of 28/11, multiple monitoring stations in Hanoi recorded air quality index levels rapidly rising to "very unhealthy", marking the first time this winter season (2025-2026) that air quality has posed a serious threat to public health.
