The odd-even car rationing scheme will be implemented in Delhi after the Supreme Court reviews its effectiveness and issues an order while artificial rain through cloud seeding will be attempted around November 20 to combat air pollution which breached the severe category again on Wednesday.

In view of the worsening air quality, the Delhi government announced that the December winter break of all schools has been rescheduled and it will be now from November 9 to November 18.

Also, the transport department has been issued directions to ban app-based taxis "in accordance with the Supreme Court's orders", according to Delhi Environment Minister Gopal Rai.

However, senior officials said a detailed order will make it clear whether the ban will come into effect from this week or will only be effective during the time of odd-even car rationing scheme is in place.

The Supreme Court on Tuesday had asked the Delhi government to consider that only taxis registered in the city ply on roads here, saying a large number of taxis registered in other states were seen on roads carrying only one passenger.

Rai also said the Delhi government will attempt to induce artificial rain through cloud seeding around November 20-21 to combat air pollution in the city. He said that he held a meeting with scientists from IIT-Kanpur who told him that cloud seeding could only be attempted if there were clouds or moisture in the atmosphere.

"Experts anticipate that such conditions could develop around November 20-21. We have asked the scientists to prepare a proposal in this regard which will be submitted to the Supreme Court," he added.

The Delhi government directed officials to immediately restart the Connaught Place smog tower and a study to identify the sources of pollution in the city. Rai had claimed that the two projects were unilaterally stalled by Delhi Pollution Control Committee Chairman Ashwani Kumar without informing the government.

Meanwhile, a day after the Supreme Court questioned the effectiveness of the odd-even car rationing scheme, which the Delhi government plans to implement from November 13 to 20, and termed it as "all optics", Rai said a decision to implement it will be made only after the apex court reviews its effectiveness and issues an order.

The matter will be heard by the court on Friday.

Rai said the government would submit the results of two major studies conducted by the Energy Policy Institute of the University of Chicago and the Delhi Technical University to determine the scheme's effectiveness for the apex court's review.

The Energy Policy Institute at the University of Chicago and the Evidence for Policy Design analysed the impact of the odd-even system in 2016 and found that Delhi saw a 14-16 per cent reduction in PM2.5 levels during the hours it remained in force in January that year.

As Delhi's air quality again dropped to the 'severe' category on Wednesday with the 24-hour average Air Quality Index (AQI) recorded at 426, Delhi Mayor Shelly Oberoi said open burning of garbage, dumping of construction waste and use of tandoors in restaurants were among the top contributors to rising air pollution in the national capital.

The Municipal Corporation of Delhi (MCD) has collected nearly Rs 1.51 crore in seven days from fines imposed on violators flouting the ban on these activities, she added.

Several cities across the Indo-Gangetic plains reported hazardous air quality with neighbouring Ghaziabad recording an AQI of 384, Gurugram 385, Noida 405, Greater Noida 478 and Faridabad 425.

According to data from the Decision Support System, a numerical model-based framework capable of identifying sources of particulate matter pollution in Delhi, stubble burning in neighbouring states, especially Punjab and Haryana, accounted for 38 per cent of the air pollution in Delhi on Wednesday. It is likely to be 27 per cent on Thursday.

With no respite from the toxic smog, the political blame game continued with the Aam Aadmi Party accusing the BJP government in Haryana of being the "biggest culprit" behind pollution in Delhi. A day ago, the Supreme Court remarked that there cannot be a "political battle" over the issue of pollution all the time.

There was no immediate reaction from the BJP or the Haryana government on the AAP's allegations.

However, on Tuesday Haryana Chief Minister Manohar Lal Khattar had said air pollution was not restricted by borders. He claimed that people in his state as well as in Delhi were suffering with Punjab reporting several cases of crop-residue burning.

According to the Ministry of Earth Sciences' Air Quality Early Warning System for Delhi-NCR, the region is likely to experience 'severe' air quality for another five to six days.

Doctors say breathing in the polluted air of Delhi is equivalent to the harmful effects of smoking approximately 10 cigarettes a day.

Prolonged exposure to high levels of pollution can cause or exacerbate respiratory problems such as asthma, bronchitis and chronic obstructive pulmonary disease (COPD) and dramatically raise the risk of cardiovascular disease, said Rajesh Chawla, senior consultant in pulmonology and critical care at the Indraprastha Apollo Hospital.

Stringent restrictions mandated under the final stage of the Central government's air pollution control plan for Delhi-NCR called the Graded Response Action Plan (GRAP), have also been implemented in the capital.

The restrictions under Stage IV of GRAP, including a ban on all kinds of construction work and the entry of polluting trucks into Delhi, took effect on Sunday after the air quality in the city dropped to 'severe plus' (AQI above 450) levels.

GRAP categorises actions into four stages: Stage I - Poor (AQI 201-300); Stage II - Very Poor (AQI 301-400); Stage III - Severe (AQI 401-450); and Stage IV - Severe Plus (AQI above 450).

Unfavourable meteorological conditions, combined with vehicular emissions, paddy straw burning, firecrackers and other local pollution sources contribute to hazardous air quality levels in Delhi-NCR during the winter every year.

According to a DPCC analysis, Delhi sees peak pollution from November 1 to November 15 every year when the number of stubble burning incidents in Punjab and Haryana increased.

(Except for the headline, this story, from a syndicated feed, has not been edited by staff)