Delhi’s air quality deteriorated sharply on Sunday morning as the city’s Air Quality Index (AQI) surged to 391 at 8 am, marking the highest reading of the season and inching dangerously close to the ‘severe’ category. This spike comes despite a prolonged stretch of poor air in recent weeks and growing concerns among residents and health experts. Though pollution levels have reached thresholds that the Supreme Court had earlier said should automatically trigger stricter measures under the Graded Response Action Plan (GRAP), authorities have held back on invoking Stage 3 restrictions.

The national capital has not officially recorded a ‘severe’ air day this year. The last such instance occurred on December 23, 2024, when the city logged an AQI of 406. Sunday’s reading surpasses the season’s earlier peak of 388 recorded on November 2, escalating questions about the delay in implementing tougher measures. Last December, the Supreme Court directed that GRAP Stage 3 should be triggered at an AQI of 350, while Stage 4, the most stringent set of curbs, must be imposed at 400. With the AQI nearing both these marks and the original GRAP Stage 3 threshold of 400 likely to be breached soon, the absence of further action has sparked uncertainty around the city’s pollution management strategy.

Amid intensifying smog and public frustration, Delhi Chief Minister Rekha Gupta urged residents to reduce personal vehicle use by opting for carpooling, taking public transport, or arranging work-from-home options wherever possible. Gupta’s advisory sought to prevent further deterioration in air quality while also acknowledging the role of public cooperation during high-pollution episodes.

The Delhi Pollution Control Committee (DPCC), meanwhile, held a press conference to address allegations of manipulated or faulty monitoring data coming from Delhi’s air quality stations. The panel dismissed these claims, arguing that AQI levels had actually improved in the first week of November compared to the same period in 2024. The DPCC also reiterated confidence in its measuring systems, responding to criticism that some stations show figures far lower or higher than surrounding monitors.

However, data from the Central Pollution Control Board (CPCB)’s Sameer app at 8 am revealed a grim picture: 23 of Delhi’s 39 active monitoring stations had already entered the ‘severe’ zone. Rohini recorded the highest pollution levels at 435, followed closely by Wazirpur at 434—both indicative of extremely hazardous air. Interestingly, the NSUT Dwarka station reported an AQI of 200, a “moderate” reading and a stark outlier compared to the rest of the city engulfed in thick smog. Observers have noted that such discrepancies in readings may be due to local wind patterns, micro-environment differences, or equipment calibration cycles.

As per CPCB classification, AQI between 51 and 100 is considered “satisfactory,” 101 to 200 “moderate,” 201 to 300 “poor,” 301 to 400 “very poor,” and above 400 “severe.” The health implications of scores near or above 400 can be profound, especially for vulnerable groups such as children, elderly individuals, and those with respiratory illnesses.

Should GRAP Stage 3 be invoked, the capital and its adjoining NCR districts—Gurugram, Faridabad, Ghaziabad, and Gautam Buddh Nagar—would face a sweeping list of restrictions. These include a ban on private BS-3 petrol and BS-4 diesel vehicles, a complete halt to all private construction and demolition activities, and a prohibition on stone crushers, mining operations, and associated tasks. Additionally, non-essential diesel-operated BS-4 medium goods vehicles would be barred, and entry of all BS-4 and lower diesel light commercial vehicles registered outside Delhi would be restricted, except for those providing essential services or delivering essential goods.

Education would also come under the ambit of Stage 3. Schools up to Class 5 in Delhi and adjoining districts would be required to switch to hybrid teaching, combining online and on-campus classes to reduce exposure to toxic air. Further, the plan recommends staggered office timings for public-sector departments and municipal bodies across Delhi and the NCR to reduce peak-hour traffic emissions.

Meteorological conditions on Sunday added another layer to the city’s pollution concerns. Delhi recorded a minimum temperature of 11.6 degrees Celsius—three degrees below the seasonal normal. This reading was marginally higher than Saturday’s low of 11 degrees Celsius, the lowest so far this season. The colder temperatures, combined with light winds and high humidity, create ideal conditions for pollutants to remain trapped close to the surface, a phenomenon known as temperature inversion.

The presence of northwesterly winds has also increased the likelihood of stubble smoke intrusion from neighbouring states. The Decision Support System (DSS), which provides forecasts on pollution sources, has predicted that farm fire smoke will contribute more than 32 percent to Delhi’s PM2.5 concentration on Sunday. Such contributions tend to fluctuate based on wind speed and direction but can amplify already high pollution levels.

The annual pattern of deteriorating air quality during the onset of winter continues to highlight both regional and local challenges. While stubble burning plays a significant role in episodic spikes, Delhi’s baseline pollution—stemming from vehicles, construction dust, waste burning, industrial activities, and residential emissions—remains worryingly high throughout the year. With the capital’s air quality reaching hazardous levels even before the full onset of peak winter, experts argue that emergency responses alone cannot resolve the crisis without structural reforms in sectors contributing to pollution.

Public health concerns remain at the forefront. Doctors and health agencies have warned that prolonged exposure to AQI levels above 300 can result in widespread respiratory distress, worsen chronic conditions such as asthma and bronchitis, and heighten the risk of cardiovascular complications. Children are at particularly high risk because of their developing lungs and higher breathing rates. The elderly and those with pre-existing heart or lung conditions also face severe health challenges during prolonged smog episodes.

As Delhi enters another pollution-heavy season, the city finds itself caught between administrative hesitation, judicial directives, meteorological challenges, and public anxiety. Whether GRAP Stage 3 interventions will be implemented in the coming days remains uncertain, but with AQI levels hovering near the ‘severe’ threshold, the capital’s worsening air quality continues to demand urgent and coordinated action.