India’s capital New Delhi has the most polluted air in the world, according to an air quality watchdog.

Two other Indian cities, Kolkata and Mumbai, also made the dirty top 10, at numbers six and nine, respectively, said Swiss-based IQ AirVisual late Friday.

“For nine consecutive days from Sunday, October 27, 2019, overall Delhi air quality was in the hazardous zone, a level at which the entire population is likely to be affected,” said an IQ AirVisual statement.

Schools in Delhi were closed on Thursday and Friday as the air quality in the city reached dangerously high levels.

Read more: New Delhi air is world's most polluted: Watchdog group