In a live ranking Saturday by IQAir, a Swiss air monitoring company, Hanoi ranked 13th on a list of the most polluted major cities. The fog hanging over Hanoi isn’t just pollution; it’s a ...

The air was so bad, and the nature of my work means that I have to be outside,” Mã Thị Dung, 50, a peanut seller in Hanoi’s Old Town, said in an interview this month.

Presidential alerts began blaring on cell phones at 1:30pm on Thursday across this city of more than two million people: “[Air Defense Drill] Missile attack. Seek immediate shelter.” Then came the air ...