NEW DELHI (Reuters) - India’s top court censured the central government for its inaction in fighting pollution on Wednesday, as poisonous smog choked the streets of the capital New Delhi forcing schools to shut and half of vehicles to be banned from the streets.

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Cool temperatures and stagnant air trapped smog over the capital, pushing pollution to “severe” levels in many places with no immediate relief in sight, government agencies said.

“The whole of North India is suffering and not much has been done by the government,” Chief Justice Ranjan Gogoi and Justice S.A. Bobde said in a statement on behalf of the Supreme Court, which has a history of intervening over air pollution.

The overall air quality index (AQI) in Delhi was 494, according to the monitoring agency SAFAR. The index measures the levels of airborne PM 2.5 - particles that can reach deep into the lungs. Anything above 60 is considered unhealthy.

It was above 500 in parts of the city, representing a threat to healthy people as well as those with pre-existing conditions.

The city government has restricted private cars until Nov. 15 with an “odd-even” system, banning them on alternate dates based on licence plate numbers. Chief minister Arvind Kejriwal said his government could extend the bans if needed.

The poisonous air also hung over a two-day visit by Prince Charles, heir to the British throne. On his first day in smoggy Delhi, Charles, 70, visited the India Meteorological Department and the Delhi War cemetery, among other sites.

He was seen in open areas without a protective mask. His office declined to comment on the smog.

With the cool season setting in, the city was likely to suffer for weeks.

“Now that it is getting colder, air is not rising high enough to disperse pollutants. The whole trapping is happening close to the ground,” said Anumita Roy Chowdhury, an executive director at the Centre for Science and Environment, a Delhi-based research and advocacy organisation.

“Emergency measures cannot clear the air up when there is no wind to blow pollution away. It is a day-to-day battle right now,” she said.

The Environment Pollution (Prevention & Control) Authority (EPCA), a body appointed by the Supreme Court, recommended shutting down schools for two days.

“...The current weather conditions are trapping pollutants and without any possibility of dispersion for the next two days, the condition of air quality is extremely unhealthy,” Bhure Lal, chairman of EPCA, said in a letter to the city government of Delhi and its neighbouring states.

Delhi’s smog could get even worse, SAFAR said, as farmers burning stubble in areas around the city have been generating clouds of acrid smoke.

“No sudden recovery is expected under this condition at least for the next two days and AQI is likely to deteriorate further,” it said.