Authorities in New Delhi, the Indian capital have announced strict restrictions on the use of private cars from November 4 to 15 to reduce pollution and improve air quality that tends to deteriorate sharply during winter periods.

Known as the world’s most polluted city, New Delhi is plagued by vehicle and industrial emissions, dust from building sites, and smoke from the burning of rubbish and crop residue in northern India.

Speaking at a news conference on Friday, New Delhi Chief Minister, Arvind Kejriwal, said private cars will only be allowed to use the roads on alternate days during the period.

According to the plan, which was first implemented in 2018, private vehicles will be allowed on the roads only on alternate days, depending on whether their license plates end in an even or an odd number.

“Pollution levels have come down in Delhi recently, and we’re determined and committed to bring them down further and that’s why we’ve decided to introduce these steps,” Kejriwal said.

The city also aims to introduce 1,000 electric buses, Kejriwal said, as well as policies to promote other electric vehicles.

The Delhi government has identified “pollution hot spots” it can target to help improve air quality in the city, he said.

New Delhi government would also distribute free face masks in the city, he said, as part of efforts to encourage people to reduce their exposure to polluted air.

As winter approaches each year, wind speeds tend to drop after the monsoon season that ends in September, meaning smog and other pollutants hang in the air. The problem is exacerbated as people let off fireworks to celebrate the Hindu festival of Diwali in late October or early November.

North Indian cities, including Delhi, top a list of places with the worst air in the world, according to the World Health Organization (WHO).

The WHO database of more than 2,600 cities shows that 14 of the 18 most polluted cities on the planet are in northern India, based on the amount of particulate matter under 2.5 micrograms in size found in every cubic metre of air.