Delhi Paralyzed: Dense Fog Halts Air and Rail Travel, AQI Reaches ‘Severe’ Levels 

On December 15, 2025, a dense combination of fog and severe smog paralyzed Delhi, reducing visibility to near-zero levels and causing major transport disruptions. The crisis severely impacted over 75 flights at Indira Gandhi International Airport, leading to 40 cancellations and 4 diversions as airlines like IndiGo and Air India issued safety advisories, while over a dozen trains experienced delays of up to four hours. Compounding the travel chaos, the city’s Air Quality Index soared to 433 (‘Severe’ category), creating a public health emergency and highlighting the dangerous synergy between winter meteorological conditions and chronic anthropogenic pollution that defines North India’s recurring winter crisis.

Delhi Paralyzed: Dense Fog Halts Air and Rail Travel, AQI Reaches ‘Severe’ Levels 

A thick, grey shroud over India’s capital brought one of its busiest airports to a near-standstill, turning Monday morning into a chaotic tableau of delayed passengers, canceled flights, and a stark reminder of the city’s perennial winter battle with pollution. 

The Indira Gandhi International Airport (IGI), typically a buzzing hive of activity, fell into an unusual quiet on the morning of December 15, 2025. A dense, impenetrable blanket of fog and smog descended upon Delhi and the wider National Capital Region (NCR), reducing visibility to as low as 50 meters in some areas and creating near-zero conditions in others like Uttar Pradesh’s Hindon. The crisis was twofold: a severe transportation breakdown and a public health emergency, with the Air Quality Index (AQI) skyrocketing to 433, deep into the ‘severe’ category. This event was not merely a weather inconvenience but a systemic stress test for India’s infrastructure, affecting over 75 flights and dozens of trains, and leaving thousands of passengers stranded. 

The human impact was immediate and widespread. At airport terminals, clusters of weary travelers huddled around information boards flashing a relentless stream of delays and cancellations. Ground staff from major airlines like IndiGo and Air India worked to manage growing crowds, distributing advisories and rebooking passengers. Meanwhile, on the roads, vehicles inched forward with hazard lights blinking, navigating a world shrunk to a few car lengths ahead. The familiar winter plight of North India had arrived with a vengeance, signaling the start of what is often the most challenging season for the region. 

1. The Morning the Capital Stood Still: A Timeline of Disruption

The crisis unfolded in the early hours of Monday. By 4:30 AM, the Palam observatory reported visibility had dropped to around 100 meters. Within an hour, it plummeted further to just 50 meters, with light westerly winds doing little to disperse the thick fog. Conditions were equally dire at the Safdarjung station. The India Meteorological Department (IMD) promptly issued an orange alert for dense fog, warning residents of hazardous travel conditions. 

The domino effect on transportation began swiftly: 

• Aviation Chaos: IGI Airport, one of the world’s busiest, saw operations severely crippled. Airlines were forced into a difficult position—prioritize safety over schedule. IndiGo announced proactive cancellations, stating the move was to “ensure safe and compliant operations” and to prevent passengers from enduring endless waits at the airport. Air India followed suit, publishing a long list of canceled flights, including key domestic routes like AI2767/2768 and AI1787/1872. 

• Rail Network Snarls: The fog’s reach extended well beyond the runway. The New Delhi Railway Station reported significant delays for over a dozen incoming trains. Long-distance services like the Bihar Sampark Kranti were running over four hours late, while the GT Express faced similar delays. The Poorva and Humsafar Expresses were each delayed by more than three hours, disrupting the plans of thousands of passengers. 

• Regional Spread: The fog was not confined to Delhi. Reports from Rajasthan’s Dholpur and Uttar Pradesh’s Mainpuri painted a similar picture, with residents describing a sudden, intense drop in temperature and visibility, bringing daily life and commerce to a virtual standstill. 

2. Decoding the White-Out: The Science Behind the Smog and Fog

This disruptive phenomenon is a toxic marriage of meteorology and pollution. Winter fog in the Indo-Gangetic plains is a common climatic feature. As temperatures drop overnight, moisture in the air condenses into tiny water droplets suspended near the ground. However, what transforms this simple fog into a persistent, choking smog is the presence of anthropogenic pollutants. 

The AQI reading of 433, classified as ‘severe,’ indicates a high concentration of Particulate Matter (PM2.5 and PM10), along with other noxious gases like nitrogen dioxide and carbon monoxide. These particles act as nuclei around which water vapor can condense, making the fog denser, more persistent, and far more hazardous to breathe. This synergy between pollution and weather creates a lid over the city, trapping cool air and pollutants underneath—a phenomenon known as a temperature inversion. The result is the grey, soupy haze that reduces visibility to zero and penetrates lungs, posing serious risks, especially to children, the elderly, and those with respiratory conditions. 

3. The Ripple Effect: Economic and Human Costs

The cost of a day like this is measured in more than just inconvenience. The economic impact runs deep. For airlines, mass cancellations and delays mean direct losses from refunds, re-routing, and added operational costs for crew and aircraft management. The aviation industry also faces reputational damage and a loss of passenger trust during the critical holiday travel season. 

The human cost is more poignant. Stranded passengers face financial strain from unexpected hotel stays, meals, and missed connections. The stress and anxiety of uncertain travel plans take a significant psychological toll. For daily wage workers and those in the informal economy, a day of paralyzed transport can mean a day without income. Furthermore, the ‘severe’ AQI level constitutes a public health crisis, with exposure linked to increased hospital admissions for asthma, bronchitis, and heart attacks, placing additional burden on the healthcare system. 

4. Navigating the Crisis: Official Responses and Passenger Advisories

In response to the escalating situation, a multi-agency advisory framework swung into action: 

• The Ministry of Civil Aviation issued a heavy fog alert for all airports in Northern India, urging passengers to check flight statuses directly with airlines before heading to terminals. 

• Delhi Airport authorities released statements updating passengers on improving runway visibility while cautioning that delays would persist. 

• Airlines like IndiGo and Air India used social media platforms extensively to communicate cancellations, offering waivers for rescheduling and full refunds for canceled flights. Their advisories consistently emphasized passenger safety as the non-negotiable priority behind all operational decisions. 

For affected travelers, the key recommendations were clear: constantly monitor official flight statuses via airline apps or websites, allow for extensive extra travel time to reach airports or stations, and ensure access to necessary medications, especially for those with health vulnerabilities, given the poor air quality. 

5. A Recurring Challenge: Long-Term Implications and Solutions

The events of December 15 are not an anomaly but a recurring pattern that intensifies each winter. They underscore a critical need for systemic, long-term solutions that go beyond crisis management. Key focus areas include: 

• Technological Investment: Accelerating the installation of CAT III Instrument Landing Systems (ILS) at all major airports in North India. This technology allows aircraft to land in very low visibility (as low as 50 meters), thereby reducing the disruption caused by fog. While Delhi’s main runways are equipped, broader regional implementation is crucial. 

• Pollution Mitigation: Addressing the fog problem is inextricably linked to tackling Delhi’s chronic air pollution. This requires sustained, year-round efforts to control stubble burning in neighboring states, reduce vehicular and industrial emissions, and transition to cleaner energy sources. The Graded Response Action Plan (GRAP) must be enforced stringently and proactively. 

• Public Communication Protocols: Developing a unified, real-time information system for all modes of transport (air, rail, road) could significantly reduce passenger distress. Clear, centralized communication about delays, cancellations, and alternative options is essential. 

The table below summarizes the core data from the December 15, 2025, fog disruption: 

As the day progressed and the sun’s weak light attempted to pierce the gloom, visibility slowly improved at Delhi’s runways. Flights gradually resumed, and the backlog of passengers began to clear. However, the deeper malaise lingered in the form of hazardous air. The event served as a powerful, tangible reminder of a complex environmental and infrastructural challenge. It highlighted the urgent need for integrated solutions that combine advanced technology for transportation resilience with unwavering commitment to cleaning the region’s air. Until then, the annual struggle against the winter smog will continue to test the resilience of the millions who call North India home.