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Toxic smog tightens grip on Delhi; air quality expected to remain ‘severe’ for coming days

Delhi’s air quality index (AQI) rose sharply through the day, touching 410 at 11 pm, breaching the “severe” threshold in the night.

Updated on: Dec 21, 2025, 08:17:39 IST
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Air pollution levels in Delhi edged close to the “severe” category on Sunday as dense smog, biting cold and thick blankets of fog swept across large parts of northern India.

New Delhi, India – Dec. 20, 2025: A passenger train moves through dense fog on a cold winter morning at Tilak Marg station in New Delhi, India, on Saturday, December 20, 2025. (RAJ K RAJ /HT PHOTO)
New Delhi, India – Dec. 20, 2025: A passenger train moves through dense fog on a cold winter morning at Tilak Marg station in New Delhi, India, on Saturday, December 20, 2025. (RAJ K RAJ /HT PHOTO)

Delhi’s air quality index (AQI) rose sharply through the day, touching 410 at 11 pm, breaching the “severe” threshold in the night. By 6:30 am on Sunday, the AQI showed marginal improvement but remained near-severe at 396, according to the ministry of earth sciences’ Air Quality Early Warning System for Delhi.

The system’s forecast warned of persistently hazardous conditions, stating: “The air quality is likely to be in the Severe category from 20.12.2025 to 22.12.2025. The air quality is likely be in the Very Poor category on 23.12.2025."

According to the bulletin, the outlook for the next six days remains worrying, with air quality “likely to be in the Very Poor to Severe category.”

Several Delhi areas record hazardous air

Data from the Central Pollution Control Board’s Sameer app showed multiple monitoring stations across the capital reporting extremely poor air quality in the early morning hours.

Among the worst-hit were Chandni Chowk (455), Wazirpur (449), Rohini (444), Jahangirpuri (444), Anand Vihar (438) and Mundka (436), as of 6:05 am, placing them firmly in the “severe” range.

Smog engulfs capital city

The India Meteorological Department (IMD) warned of dense fog as the temperatures plunged alongside the pollution spike.

For Sunday, the weather agency issued orange alerts — the second-highest warning level — across large parts of Uttar Pradesh, Haryana, Chandigarh and Delhi, forecasting dense to very dense fog conditions and urging authorities and residents to brace for severe disruptions.

As reported by HT earlier, a satellite image captured at 9 am highlighted the vast scale of the smog and fog episode — a continuous band stretching from the Kashmir valley through Punjab, Haryana, Delhi, Uttarakhand, Uttar Pradesh, Bihar, Jharkhand and West Bengal, extending into parts of Madhya Pradesh.

The national capital recorded a maximum temperature of around 17 degrees Celsius and a minimum of 8 degrees Celsius, reflecting cold day conditions amid persistent smog and fog across the city.

Flight ops disrupted at Delhi airport

Visibility at the Indira Gandhi International Airport remained poor due to dense fog. At 2:30 am IST, general visibility was recorded at just 600 metres, affecting flight operations during the late-night and early-morning hours.

India’s largest carrier, IndiGo, issued a travel advisory, cautioning passengers about possible disruptions due to early-morning fog expected across Delhi and several parts of northern India on Sunday.

“Early-morning fog is expected to affect visibility across Delhi and parts of northern India. During these hours, visibility can suddenly reduce, impacting flight operations.” the advisory said, adding that safety remains the airline’s top priority.

At Delhi airport, flight operations were disrupted for the fifth straight day due to low visibility, with 66 arriving and 63 departing flights cancelled, as of Saturday.

Data from Flightradar24 showed widespread delays through the day, with 220 arrivals and more than 400 departures running behind schedule by Saturday evening. The average delay exceeded 30 minutes.

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