Delhi's average AQI reached 402 at 5 am on November 13, with several monitoring stations recording readings above 400.
PM2.5 concentration more than doubled in 24 hours to 244 micrograms per cubic metre on Thursday evening.
Weak winds, a shallow mixing layer and smoke from crop-residue fires contributed to the deterioration in air quality.
Delhi's average Air Quality Index (AQI) reached 402 at 5 am on Friday, November 13, entering the severe category, while several monitoring stations also recorded readings above 400. IIT Delhi recorded an AQI of 488 at 3 am, while Chandni Chowk registered 474 and North Campus 473, according to the Indian Institute of Tropical Meteorology's (IITM) Air Quality Early Warning System. A layer of haze persisted over the national capital.
The deterioration followed a rise in Delhi's rolling 24-hour AQI on Thursday, from 313 at 2 am to 366 at 6 pm and 387 by 10 pm, according to CPCB data. The CPCB's official 4 pm bulletin, meanwhile, recorded the city's average AQI at 350, placing it in the very poor category. The figures reflect different reporting periods, with the city's air quality deteriorating further through Thursday evening.
ITO, Anand Vihar Record Severe AQI As Readings Cross 400
CPCB monitoring-station data available on Friday morning showed an AQI of 455 at ITO, while Anand Vihar and Akshardham recorded 414 each. Rajokri Border registered 402, placing all four locations in the severe category.
Dwarka Expressway recorded an AQI of 369, in the very poor category, while Dhaula Kuan registered 161, in the moderate category.
Early morning visuals from Kartavya Path and the India Gate area showed a layer of haze over the Capital.
Delhi's PM2.5 concentration more than doubled in 24 hours to reach 244 micrograms per cubic metre by 6 pm on Thursday, more than four times the national 24-hour standard of 60 micrograms per cubic metre, Hindustan Times reported. By 10 pm, 21 of the 58 monitoring stations reporting had recorded severe AQI levels, the newspaper said.
Weak Winds And Farm Fire Smoke Contribute To Delhi's Pollution
Meteorological conditions also contributed to the accumulation of pollutants. According to Hindustan Times, Delhi's mixing layer, which affects how pollutants disperse, was around 400 metres on Thursday afternoon, down from 1,400 metres on Tuesday.
Winds within the mixing layer averaged 8 km/h, compared with the usual 13 km/h, further limiting the dispersion of pollutants, the report said.
The report also noted that north-westerly winds were carrying smoke from crop-residue fires in Punjab and Haryana towards Delhi. These winds were moving at around 34 kmph at an altitude of one to two kilometres, rather than at the surface. Sunil Dahiya, founder and lead analyst at Envirocatalysts, told the newspaper: "Overnight, smoke from crop-residue fires in Punjab and Haryana drifted in from the north-west."
Farm fires were not the only source of pollution. A revised forecast by the Decision Support System (DSS) for Delhi, released on Thursday, projected transport emissions to account for 18.5% of the city's pollution load on Friday, while stubble burning was expected to contribute 5.3%.
The Commission for Air Quality Management (CAQM) invoked Stage III of the Graded Response Action Plan (GRAP) across Delhi-NCR on November 6. The restrictions remained in force on November 13, alongside measures under Stages I and II.
Air pollution can aggravate existing heart, kidney and lung conditions, said Dr Manoj Sharma, Director of Internal Medicine at Fortis Hospital, Vasant Kunj.
He said children were particularly vulnerable because their lungs and immune systems were still developing, making them more susceptible to respiratory infections, bronchitis and pneumonia. He advised people to wear N95 masks outdoors in polluted areas but cautioned against exercising while wearing one.
