NEW DELHI, INDIA — Flights to and from New Delhi’s international airport here were delayed and diverted on Sunday as heavy pollution reached unbearable levels, leaving the city blanketed with heavy smog.

At least 37 flights including one international flight were diverted from Indira Gandhi International Airport due to poor visibility.

The air quality in the Indian capital reached hazardous level of pollution in the city.

New Delhi’s Chief Minister Arvind Kejriwal tweeted that pollution was unbearable across North India.

New Delhi has been one of the most polluted cities in the world. According to Greenpeace and AirVisual, that seven of the world’s 10 cities with the worst air pollution are in India.

Major airlines like Air India and SpiceJet warned of delays and cancellations to flights to and from the international airport on Sunday.

According to Indian government figures from 2018, New Delhi is more than 18 million people living in that city and 8.8 million registered motor vehicles, more than any other Indian City.

Pollution in the city worsens this time of year as temperature drops and farmers light fires to clear their land. During the Hindu festival, smoke from firecrackers set off to Diwali and through that, it also adds to smog level.

Smog has blanketed the city in recent days, severely lessen the visibility and limiting all the necessary outdoor activities.

On Friday, Kejriwal announced that authorities had begun to distribute 5 million face masks to school children in the city. (Cate Pallarco/IAMIGO/CNS)