The Delhi, Haryana and Uttar Pradesh governments on Monday suspended physical classes for all students, including Classes 10 and 12, in the National Capital Region as air quality remained in the “severe plus” category for the second day in a row, NDTV reported.

On Sunday, the Delhi government shifted schools online for all students, except for Classes 10 and 12, due to the deteriorating pollution levels. Holidays were also declared for students up to Class 5 in Haryana. The Uttar Pradesh government had not announced any measure.

The order to suspend all physical classes came hours after the Supreme Court directed all governments in the National Capital Region to consider suspending in-person classes for students.

A bench of Justices Abhay S Oka and Augustine George Masih made the recommendation while dealing with a matter related to air pollution caused by stubble burning, firecrackers, vehicular emissions, garbage burning and industrial pollution.

Following the recommendation, Delhi Chief Minister Atishi announced that “physical classes shall be suspended for Class 10 and 12 as well, and all studies will be shifted online” from Tuesday.

In Haryana, the Gurugram administration said that all classes would be discontinued till November 23. “Online classes will be conducted in lieu of physical classes, in all Government and Private Schools in the district,” the office of the deputy commissioner said, NDTV reported.

The Ghaziabad district magistrate in Uttar Pradesh also announced that all classes would be suspended in the region. Physical classes were suspended till November 23 in Noida.

On Tuesday, the daily average air quality index, or AQI, in Delhi stood at 484 at 10 am, according to data from the Central Pollution Control Board.

At 7 am, the national capital recorded an average AQI of 492. Several areas, including Alipur, Anand Vihar, Bawana, Narela, Pusa and Sonia Vihar, also saw an AQI of 500 at this time, The Indian Express reported. Out of 38 air quality monitoring stations in Delhi, 21 observed AQI 490 or above.

An index value between 0 and 50 indicates “good” air quality, between 51 and 100 indicates “satisfactory” air quality and between 101 and 200 indicates “moderate” air quality.

As the index value increases further, air quality deteriorates. A value of 201 and 300 means “poor” air quality while between 301 and 400 indicates “very poor” air.

Between 401 and 450 indicates “severe” air pollution while anything above the 450 threshold is termed “severe plus”. At these levels, healthy people can experience respiratory illnesses from prolonged exposure to air pollution.

During the hearing on Monday, the court directed the governments of Delhi and adjoining areas in the National Capital Region to continue implementing strict anti-pollution measures under Stage 4 of the Graded Response Action Plan, or GRAP, till further orders even if the air quality improves to settle below an index value of 450.

The court also rapped the Delhi government for delaying the implementation of stricter anti-air pollution measures under GRAP Stage 4.

The GRAP is a set of incremental anti-pollution measures that are triggered to prevent the further worsening of air quality once it reaches a certain threshold in the National Capital Region.

Stage 1 of GRAP is activated when the AQI is in the “poor” category. The second, third and fourth stages are activated when the AQI crosses the “very poor”, “severe” category and “severe plus” category.

The Commission for Air Quality Management in the National Capital Region ordered the implementation of GRAP Stage 4 measures from Monday, which banned the entry of trucks into the national capital and temporarily halted the construction of public projects.