Delhi’s average air quality index (AQI) was 460 on Sunday, rising close to the November 9 season-high of 486. This was because of a fall in temperature, increased cloud cover, lower wind speed at the ground level, and winds at higher altitudes carrying pollutants from Punjab and Haryana, according to the Central Pollution Control Board (CPCB).

The AQI had improved to 403 on Saturday, when the wind speed at lower altitudes had picked up. For the last six days, the air quality has remained in the “severe” zone across the National Capital Region, prompting to the Indian Medical Association to declare a health emergency.

The figure in other NCR cities, too, was alarmingly high on Sunday – 468 in Faridabad, 498 in Ghaziabad, 460 in Gurgaon and 492 in Noida. Most schools in Delhi are set to reopen on Monday after being shut for four days due to the pollution, but schools in Gurgaon will remain closed.

Though there could be some respite on Tuesday, light rain on Wednesday may make the air quality even worse, warned Dipankar Saha, head of the air lab at the CPCB.

A new pollution-fighting mechanism, the Graded Response Action Plan, is in place in the city. Several steps have been announced -- ban on construction activities, hike in parking fees and ban on diesel gensets -- but ground reports show that the Delhi government and local civic bodies have been sluggish on implementation.

On Saturday, the National Green Tribunal gave its nod to the odd-even scheme, which allows only odd- and even-numbered private vehicles on the roads on alternate days, from November 13 to 17. However, it strongly rejected on the government’s plan to let two-wheelers and vehicles driven by women stay on the roads. Given these new conditions, the Delhi government decided to put the move on hold.

The government is arguing that the added load from two-wheeler commuters would put too much pressure on public transport, but the Opposition parties are blaming the Aam Aadmi Party government for being populist in exempting two-wheelers to protect its vote bank.

“Out of the city’s one crore registered vehicles, 63.2 lakh are two-wheelers. Around 40 lakh run daily on the roads. Even if half of them are exempted from riding during odd-even, at least 20 lakh persons will have to be accommodated in the available public transport. We will explain to the NGT that this will be a problem,” said an official of the government’s transport department, who asked not to be named.

Environment experts argue that two-wheelers are major contributors to air pollution and allowing them to stay on the roads defeats the purpose of the odd-even scheme. The CPCB, during a Saturday hearing, informed the NGT that vehicular emissions contribute 20% to Delhi’s foul air and of this 30% emission is by two-wheelers.

The exemption for women, too, is a sticky subject for the government because crimes against women are a big problem in the city. Immediately after the NGT ruling, Swati Maliwal, the head of the Delhi Commission for Women, urged the government to call off the odd-even scheme in light of the green tribunal’s order.

“We will explain to the NGT that we cannot compromise on women’s security,” a Delhi government official said.

United Airlines has suspended all flights to Delhi from Newark until Monday due to the air quality and was offering alternatives to passengers booked on the route to India, the US airline said on its website.

Some hospitals in Delhi are reporting patient numbers have more than tripled since a dense layer of smog settled over the city of 20 million last week, with people complaining of burning sensation in their eyes and heaviness in breathing.