A panel set up by the Supreme Court on Friday declared a public health emergency in the Delhi-National Capital Region on Friday and banned construction activity till November 5, PTI reported. All schools in Delhi will be shut till Tuesday, Chief Minister Arvind Kejriwal announced.

This came as pollution levels plummeted to severe-plus levels from Thursday night, prompting Kejriwal to say that the city had turned into a gas chamber.

The Centre-run System of Air Quality and Weather Forecasting and Research, or SAFAR, recorded a severe-plus reading of 533 for PM 2.5 pollutants – particulate matter with a diameter smaller than 2.5 micrometres. “We have to take this as a public health emergency as air pollution will have adverse health impact on all, particularly our children,” Environment Pollution (Prevention and Control) Authority Chairperson Bhure Lal told the chief secretaries of Uttar Pradesh, Haryana and Delhi.

The agency official asked public authorities to issue advisories asking people to minimise their personal exposure to pollution as far as possible. “People have also been advised to not exercise in the open till the pollution level reduces and special care should be taken of the children, aged and vulnerable population,” Lal said. “This is a grave situation and I am hoping for your personal intervention so that there is stringent enforcement and full compliance with the directions issued.”

SAFAR also said that the share of stubble burning from the neighbouring states of Punjab and Haryana in Delhi’s pollution rose to 46% on Friday, PTI reported. This is the highest figure this year.

“The effective stubble fire counts of Northern west India [Haryana and Punjab] is showing an increasing trend and on its peak value of this year [3,178] which has increased its share significantly to 46%,” SAFAR said. Low surface wind speed, dust lifting and low humidity contributed to pollution, the agency added.

“A slight improvement in AQI is expected by tomorrow but in the same severe category,” SAFAR said. “By November 3, significant improvement in air quality to the upper end of very poor is expected and by November 4 further improvement to the very poor category is expected.”

According to the Central Pollution Control Board, the Air Quality Index at 3 pm was 484. The board measures a 24-hour average. Air this bad falls in the severe category, and “affects healthy people and seriously impacts those with existing diseases”.

According to the Graded Response Action Plan, odd-even road rationing, ban on entry of trucks, ban on construction activities, and closure of schools should be enforced if the air quality continues to remain in the emergency zone.

Kejriwal has blamed crop burning in neighbouring states for the increase in pollution, and urged people to use masks. On Wednesday, Punjab Chief Minister Amarinder Singh had criticised the Aam Aadmi Party leader for blaming his government for the rising pollution in the national Capital. He claimed Kejriwal was trying to “divert public attention from his own government’s failures” by indulging in such “outright lies”. The Central Pollution Control Board has asked Punjab and Haryana to take immediate action to curb stubble burning.