Toxic smog has blanketed Vietnam's capital for more than a week, blotting out the skyline and leaving residents wheezing as Hanoi's air quality dipped to among the world's worst on Thursday.

The city of nine million ranked second only to India's New Delhi on IQAir's ranking of most polluted cities on Thursday morning, improving slightly in the afternoon.

Originally published on doc.afp.com, part of the BLOX Digital Content Exchange.