A thick layer of toxic smog covered India's capital on Friday morning as the air quality index (AQI) entered the "severe" category in several parts of the city.
The smog forms over Delhi every winter as the cold, heavy air traps construction dust, pollution from vehicles and smoke from the burning of crop stubble in neighboring states. As a result, millions of residents face respiratory illnesses every year.
"Unfavorable meteorological conditions, sudden increase in the farm fire incidents and north-westerly winds moving the pollutants to Delhi are the major causes for sudden spike in AQI," the region's Commission for Air Quality Management said on Thursday.
Videos on social media platform X, formerly Twitter, showed a grey haze over the city.
Pollution a threat to the sick
On Friday morning, the AQI reached 480, according to local monitoring stations. A level of 0-50 is considered good. Anything between 400-500 presents a danger to those with existing diseases. Residents across the city complained of itchy throats, burning eyes and difficulty in breathing.
Air quality monitoring Swiss firm IQAir put Delhi's AQI at 611 in the "hazardous" category on Friday morning.
The PM2.5 particles — considered most dangerous since they are small enough to enter the bloodstream — were nearly 35 times the daily maximum recommended by the WHO, the Swiss company said.
What is the government doing?
Delhi Chief Minister Arvind Kejriwal, late on Thursday, announced that all primary schools would be closed across the capital for at least two days.
Delhi has previously adopted several policies to curtail the number of cars on the street, pause construction activity when required and discourage farm stubble burning. The smog, however, returns every year.
Delhi's environment minister, Gopal Rai, in an interview with news agency ANI, said "It is wrong to think that the Delhi Government can control pollution completely because the matter of pollution is not of Delhi alone."
Last month, Delhi opened a pollution coordination hub — connecting 28 government departments — to zoom in on exact emission sites.
"As soon as the AQI worsens, we alert our teams on the ground and they take action immediately," said the war room's environmental engineer Anurag Pawar.