The Indian capital, Delhi, has launched a car rationing system as it battles hazardous levels of pollution.

Private cars with even and odd number plates will only be allowed on roads on alternate days from 4 to 15 November, officials said.

The system was introduced in 2016 and 2017 as well, but it’s not clear if it actually helps bring down pollution.

Levels of dangerous particles in the air – known as PM2.5 – are far higher than recommended.

The deteriorating air quality has put millions of people at the risk of respiratory illness.

Health officials have asked people to stay indoors and refrain from doing any physical activity. School are closed until Tuesday and the shutdown is likely to be extended until Friday as the city continues to choke under a thick blanket of smog.

Delhi Chief Minister Arvind Kejriwal said the car rationing system, known as the “odd-even plan”, would take hundreds of thousands of cars off the road.

Violaters will be fined 4,000 rupees (£44; $56), which has doubled from previous years.

Only emergency vehicles, taxis and two-wheelers will be allowed. Women driving alone will also be exempt from the rule.

Hundreds of teams from the police, the transport department and civil volunteers have been deployed to enforce the rule. It is likely to cause extra pressure on the public transport system.

But officials say they are prepared as extra buses and metro trains will be deployed during this period.

But there are questions if the odd-even rule will drastically reduce pollution levels. Similar measures in the past drastically reduced traffic congestion in Delhi but did not have a significant impact on pollution levels.

Experts say emission from vehicles is just one of the several factors that has made the city a “gas chamber”.

A major factor behind the high pollution levels at this time of year is farmers in neighbouring states burning crop stubble to clear their fields.

This creates a lethal cocktail of particulate matter, carbon dioxide, nitrogen dioxide and sulphur dioxide – all worsened by fireworks set off during the Hindu festival Diwali a week ago.

Vehicle fumes, construction and industrial emissions have also contributed to the smog.

How does the Odd-Even plan work?

This is the third edition of Delhi government’s “Odd-Even Plan” and it’s been introduced with a few tweaks. Here’s what you need to know if you are planning on taking out your car in the city:

Private cars with number plates ending in even and odd numbers will be allowed only on alternate days from 4 to 15 November. So, if your number plate ends with one, three, five, seven and nine, you can only drive on odd dates (4,6,8,12 and 14) and if it ends in zero, two, four, six and eight, you can drive on even dates (5,7,9,11,13 and 15).

The restrictions are in place from 8am to 8pm from Monday to Saturday and will also apply to cars coming from outside the city. Sunday is free for all.

Unlike earlier years, vehicles that run on clean fuel like CNG (compressed natural gas) will not be allowed, though electric vehicles are still exempt.

Delhi chief minister and other ministers are not exempt, though there is a fairly long list of those who’ve been granted exemption from the rule:

• All VIPs, including the president, vice-president, prime minister, government ministers, several senior politicians, judges and foreign diplomats
• Women driving alone or with only female passengers. Male children up to 12 years are allowed
• Private vehicles with male drivers on school run or on the way to hospital for medical treatment if they can “prove the emergency”
• All two-wheelers, which include motorbikes and scooters
• Taxis and auto-rickshaws
• Emergency vehicles
• Disabled drivers