The odd-even road rationing policy will be enforced in Delhi starting November 13, while all schools have been directed to suspend in-person lessons for students barring those in classes 10 and 12, state environment minister Gopal Rai announced on Monday, unveiling a raft of measures to help control the state’s unfettered pollution crisis, even as the air quality index (AQI) read “severe” for a fifth straight day.

As the Sun remained veiled and the city cloaked by a thick coat of smog, Delhi on Monday clocked an AQI of 421, after readings of 454 on Sunday, 415 on Saturday and 468 on Friday. The city recorded an AQI of 392 in the Central Pollution Control Board’s (CPCB) official 4pm bulletin on Thursday, but this number spilled past 400 just an hour later. Delhi on Monday also logged its lowest minimum temperature so far this season —13.5°C.

According to the government’s odd-even policy, private vehicles with licence plates ending in odd numbers will be allowed on the streets on odd-numbered dates, while even-numbered vehicles can ply on even dates.

The Aam Aadmi Party (AAP) in Delhi has enforced this policy thrice before (in 2016, 2017 and 2019) in the Capital, even as experts and environmentalists have underlined a gamut of concerns with the programme. Several have called it short-sighted and unscientific, while others have highlighted the long list of exemptions to the rule, especially those for taxis and two-wheelers.

Also Read | Delhi pollution: What is Odd-Even rule?

The policy, Rai said, will be effected a day after Diwali, when unfettered, illegal firecracker burning across Delhi maxes out pollution meters and keeps the city soaked in a marinade of toxic chemicals and particulate pollutants.

To be sure, he made no mention of the contours of the programme, and the details of this iteration of the scheme remain unclear.

“The decision to impose the odd-even policy has been taken as after Diwali, pollution may rise further. Odd-even will come into effect a day after Diwali, for a week’s time, so from November 13 till November 20. After that, based on the pollution levels prevailing in Delhi, further decisions can be taken,” Rai said, in a press conference after the meeting, adding that a meeting will be held on Tuesday to decide the exemptions for the vehicle rationing scheme.

According to Delhi’s 2022-23 Economic Survey, the Capital has 7,917,898 registered vehicles, of which 2,076,113 are four-wheelers and 5,268,685 are two-wheelers. The rest are goods vehicles, buses and taxis. The Capital also has 93,578 registered auto rickshaws, 85,033 taxis and 17,522 buses.

Among the neighbouring NCR towns, Greater Noida was the most polluted, with an average AQI of 420, followed by Faridabad (412), Ghaziabad (391), Noida (384) and Gurugram (373).

A toxic cocktail of smoke from paddy fields in Punjab and Haryana, local pollutants, glacially slow surface-level winds and dipping temperatures give Delhi an air emergency between end-October and November every year.

Satellites recorded 2,060 fires in Punjab on Monday, after 3,230 on Sunday, taking the year’s total to 19,453 in the state. Still, this is only a fraction of the total number of fires that farmers in the agrarian state burn this time of year.

Delhi’s pollution mess has been exacerbated by administrative inaction so far, with the AAP government directing blame at Haryana and Uttar Pradesh, but not at Punjab, a state which it rules.

In the same vein, for instance, Rai on Monday requested Delhi’s neighbouring states to implement a blanket ban on firecrackers, similar to what was in place in the Capital.

“Delhi has imposed a ban on firecrackers. With Diwali around the corner, we need to prevent further deterioration. I request the neighbouring states to implement such a ban as well,” he said, stating Delhi Police had been directed to crack down on the entry of any form of firecrackers into Delhi.

The production, sale and use of all firecrackers are banned in Delhi, while so-called green firecrackers are allowed in Haryana and Uttar Pradesh.

Meanwhile, the Delhi government’s Monday order on schools essentially extends to further classes a circular issued on Sunday saying schools will remain shut for primary students (up to Class 5) till November 10.

The order left schools and parents scrambling to make arrangements.

Aprajita Gautam, president of the Delhi Parents’ Association said, “Firstly, all students do not have mobile phones. Even if they have phones at home, parents do not want to leave their small children unsupervised, hence they have to choose between going to work or staying at home with the children.”

Delhi already has all four stages of the Graded Response Action Plan (Grap) in place, with the Commission for Air Quality Management (CAQM) invoking its most stringent measures — under Stage 4 on Sunday evening. The final stage bans all diesel light commercial vehicles registered outside Delhi and those of the non-BS6 variety from entering the Capital. Similarly, there is a ban on entry of trucks into Delhi, alongside a ban on plying of all diesel-Medium Goods Vehicles (MGV) and Heavy Goods Vehicles (HGV) in the capital. Further, all constructions and demolitions are banned in Delhi.

The AAP government first implemented the odd-even scheme in 2016, in two phases — from January 1 to 15 and then April 16 to 30. Both times however, pollution levels dropped only around 2-3%, according to a study by a team of scientists from IIT-Delhi, IIT-Kanpur, IITM-Pune, CSIR and TERI.

The scheme was also introduced again in 2017 — for a week and for 12 days in 2019. The National Green Tribunal, ahead of Delhi’s attempt in 2017, had however asked the Delhi government to explain the rationale behind implementing the scheme. The Central Pollution Control Board (CPCB) and the Delhi Pollution Control Committee (DPCC) had told the green tribunal that two-wheelers are more polluting than four-wheelers and their emissions comprise 20% of the total vehicular pollution — seeking their inclusion in this vehicle rationing scheme, but the Supreme Court had stayed this decision, making them exempt from coming under it.

In 2019, two-wheeler, electric vehicles, CNG cars, Women-only vehicles with children aged up to 12 years and vehicles occupied by physically-disabled persons were also exempted.

There may, however, be some relief in the offing for Delhi, said weather experts.

An official at the India Meteorological Department (IMD) said the wind direction, which has been northwesterly for four days, switched to southeasterly on Monday, with a western disturbance approaching northwest India.

“The disturbance will largely influence Jammu & Kashmir, but some impact is expected in Delhi too, as the wind direction will shift constantly. We expect wind speeds to pick up gradually from Tuesday afternoon,” said Kuldeep Srivastava, a scientist at IMD.

IMD in its forecast on Monday also predicted that the night-time temperature is likely to climb to 17°C by the middle of the week.