NEW DELHI (BLOOMBERG) - India has directed six coal-fired plants located around Delhi to shut down until the end of this month as part of measures to clean some of the world's dirtiest air, as a cloud of smog enveloped the city and its suburbs for nearly two weeks.

The federal Environment Ministry late Tuesday (Nov 16) also barred the entry of all trucks except those carrying essential items into the National Capital Region of Delhi and encouraged citizens to work from home to curb pollution.

The decision came after officials from the Delhi government and the neighbouring states of Uttar Pradesh, Punjab, Rajasthan and Haryana met to discuss measures to check the soaring pollution.

India's Supreme Court on Monday (Nov 15) called for urgent restrictions on vehicular movement and industrial activities in and around the capital.

The city has ordered schools to only teach online until Saturday, halted construction activities and asked some government employees to work from home after the top court called the situation an "emergency" last Saturday.

About half the 13,210MW thermal power capacities in the capital region have been ordered shut to improve air quality. Thermal capacity of 6,300 MW capacity within a 300km-radius of Delhi that has been closed down includes two units of 2,400 MW in neighbouring Haryana, two units of 2,180MW in Punjab and two of 2,320 MW in Uttar Pradesh.

India, which batted to prolong coal use at the COP26 in Glasgow last week, uses the dirtiest fossil fuel to fire almost 70 per cent of its electricity needs.

The move is unlikely to have an impact on power supplies to the Indian capital and other states.

Power companies are usually prepared for this annual exercise and tie up capacities in advance to deal with the situation.

Any step that affects power supply would be counter-productive as it could lead to a jump in the use of diesel-fueled generators.

The Supreme Court Wednesday deferred its review of the new measures to Nov 23 after the federal government's top lawyer said the pollution levels are expected to drop because of the steps taken and due to favourable wind and weather conditions after Nov 21.

During the hearing the court questioned the government on upgrading power plants and industries with non-polluting technologies.

"Stricter regulations for thermal power plants are in place. The question is of implementation," Solicitor-General Tushar Mehta told the court. "There is a lack of exercise but not of will."

The shutting down of power plants will help address emissions and cut pollution, said Ms Jyoti Pande Lavakare, author of 'Breathing Here is Injurious to Your Health' and co-founder of civil society group Care for Air.

But "we need a thought-through, ambitious plan, which is being led with leadership right from the top" to address the issue in the long term, she said.

A thick blanket of toxic haze is an annual phenomenon in the northern city and its surroundings, especially as winter arrives and temperatures dip.

Politicians and the authorities have squabbled over a solution for years, with dialogue picking up only when the pollution soars.

However, as the pollution levels ebb the debate dies down and the issue has never caused any serious political fallout.

Speaking at the Bloomberg New Economy Forum in Singapore on Wednesday, Mr Sunil Mittal, the billionaire chairman of Bharti Airtel Ltd said he would fly back to Delhi later tonight, a city that is "covered in smog."

"We can't live like this," Mr Mittal said. "We talk about 5 million people dying of the pandemic; we don't talk about how many people have been choked around the world."

The air quality index, or AQI, for New Delhi was at 244 at 8.30am local time, according to website IQAir, which monitors air pollution around the world.

Readings below 50 are considered safe, while anything above 300 is considered hazardous.

PM2.5 concentration in the air was recorded 38.7 times above the WHO annual air quality guideline value, its said.

The toxic air quality across several Indian cities is driven by a combination of factors, including vehicular and factory emissions, road dust, construction activities and stubble burning by farmers.