Hanoi, Vietnam Tops List of World’s Most Polluted Cities

On December 14, Hanoi, Vietnam was ranked by IQAir as the world’s most polluted city, with its Air Quality Index (AQI) reaching 230 at one point—surpassing Delhi, India. AQI levels at some monitoring stations even approached the dangerous threshold of 300, affecting surrounding provinces like Thanh Hoa and Thai Nguyen. The smog drastically reduced visibility in Hanoi, with residents frequently reporting symptoms like eye pain and coughing. Experts analyzed that the primary sources of this pollution were vehicle exhaust, construction dust, and straw burning. Combined with the northern region’s winter conditions of low rainfall and calm winds, pollutants accumulated at low altitudes and struggled to disperse.