Delhi&rsquo;s air quality improved marginally on Tuesday, slipping from the &lsquo;severe&rsquo; category to &lsquo;very poor&rsquo; after three consecutive days of extreme pollution, even as shallow fog continued to disrupt flight operations at the national capital&rsquo;s airport.
The 24-hour average Air Quality Index (AQI) stood at 377 at 8 am, down from 427 recorded on Monday evening. On Sunday, the AQI had peaked at 461, marking the second-worst December air quality day on record. The improvement came as wind speeds increased and fog intensity reduced, shifting from very dense conditions on Monday to shallow fog on Tuesday.
Despite the improvement, aviation operations remained under strain. More than 200 flights were delayed at Indira Gandhi International Airport by 8 am on Tuesday, largely due to the cascading impact of Monday&rsquo;s dense fog, which had forced a near five-hour halt in take-offs. On Monday alone, over 800 flights were delayed, more than 220 were cancelled and five were diverted, leaving many passengers stranded at terminals following last-minute disruptions.
Airlines also pre-emptively cancelled some services on Tuesday. Flight tracking data showed 86 arriving flights were delayed and three were cancelled, while 119 departures were delayed with no reported cancellations. A flight is classified as delayed if it departs or arrives more than 15 minutes behind schedule.
In a late-night statement on Monday, Air India said the dense fog had led to parking bay constraints at the airport, triggering delays and cancellations that caused network-wide disruptions. Anticipating similar fog conditions on Tuesday, the airline cancelled select flights in advance, offering affected passengers full refunds or free rescheduling.
IndiGo, too, issued an early-morning advisory, cautioning that fog typical of northern India during winter could slow flight movements. The airline said ground adjustments were being made to minimise inconvenience and ensure passenger comfort during waiting periods.
The Delhi airport authority said in an early-morning update that operations were steadily recovering but warned that disruptions could continue for some arrivals and departures.
Meteorological data showed visibility at the airport had improved to 600 metres by 8 am on Tuesday, compared to just 50 metres on Monday. Dense fog conditions were also reported in parts of Uttar Pradesh, including Bareilly, where visibility dropped to zero, and Lucknow, where it dipped to 50 metres in the early hours.
Weather experts forecast further improvement in both air quality and visibility during the day, with wind speeds expected to rise to around 25 km per hour. A shift in wind direction to westerly and increased wind speed were expected to help disperse pollutants and reduce fog intensity as the day progressed.

The wind direction changed to westerly on Monday

Shallow fog and lingering smog disrupt flights as air quality remains alarming

Delhi AQI ‘very poor’, fog delays 200 flights

Shallow fog and lingering smog disrupt flights as air quality remains alarming

December 16, 2025 | 17:13 IST