The National Capital Region (NCR) woke up on Tuesday under a shroud of toxic haze, as air pollution levels surged dramatically, forcing authorities to invoke Stage-3 of the Graded Response Action Plan (GRAP) for the first time this season. The Commission for Air Quality Management (CAQM) in NCR and adjoining areas took the step as the 24-hour rolling average Air Quality Index (AQI) in Delhi soared to 421 at 7 am, marking the highest reading recorded in the national capital this year.

The spike in pollution, which pushed the air quality into the ‘severe’ category, has raised alarm among citizens and authorities alike, prompting the implementation of stringent measures aimed at curbing emissions and protecting public health.

What Stage-3 Restrictions Entail

GRAP Stage-3 is invoked when the AQI crosses, or is forecasted to cross, the 400-mark, signalling a dangerous level of pollution with widespread health implications. Under the restrictions:

• Private BS-3 petrol and BS-4 diesel four-wheelers are prohibited across Delhi, Gurugram, Faridabad, Ghaziabad, and Gautam Buddh Nagar.
• Non-essential construction and demolition activities are banned, including operation of stone crushers, mining, and related activities.
• Non-essential diesel-operated BS-4 medium goods vehicles and BS-4 and lower diesel light commercial vehicles registered outside Delhi are not allowed, except those carrying essential goods or providing crucial services.
• Schools up to Class 5 in Delhi and neighbouring districts are required to switch to hybrid lessons, avoiding unnecessary travel for young students.
• Governments are advised to stagger work timings for public officers and municipal bodies in NCR to reduce vehicular congestion and emissions.

The CAQM stated that these measures are in addition to the actions already mandated under Stage-1 and Stage-2 of the plan, which focus on short-term curbs and early alerts to prevent further deterioration of air quality.

Why Pollution Spiked

Officials explained that the sudden deterioration is primarily due to calm winds, stable atmospheric conditions, and other unfavourable meteorological factors, which have prevented the dispersion of pollutants. Experts also highlighted that the haze observed across Delhi since Monday was not fog, as it persisted throughout the day, indicating a steady accumulation of pollutants.

On Monday, visibility dropped to approximately 1,000 metres in the morning, slightly improving to 1,500–2,000 metresby evening, but still well below normal. The average AQI on Monday afternoon was 362, already in the ‘very poor’ category, compared to 370 on Sunday, showing a rising trend.

Compounding the crisis, pollution data for around 10 hours on Monday—from noon to 10 pm—went missing due to a server issue, delaying the issuance of the daily national bulletin, which is typically released around 4 pm. The bulletin was eventually issued after 11 pm, with the AQI at noon remaining artificially at 345 due to missing data. By midnight, it touched 398 and crossed the 400-mark at 1 am on Tuesday, officially triggering the Stage-3 alert.

The last time Delhi recorded a ‘severe’ air quality day was December 23, 2024, when the AQI reached 406, underlining the intensity of the current pollution episode.

City-Wide Impact

Data from the Central Pollution Control Board (CPCB)’s Sameer app highlighted the severity of the situation. Out of 39 active monitoring stations across Delhi, 34 recorded ‘severe’ AQI as of 7 am on Tuesday, with readings skewed toward the higher end of the scale:

• Bawana: 462
• Wazirpur: 460
• Mundka and Punjabi Bagh: 452

The AQI classifications are as follows:

• 51–100: Satisfactory
• 101–200: Moderate
• 201–300: Poor
• 301–400: Very Poor
• 401–500: Severe

With readings consistently above 400, residents are being advised to limit outdoor activity, especially children, the elderly, and those with pre-existing respiratory or heart conditions.

Authorities Urge Public Cooperation

The CAQM emphasized the need for immediate action to prevent further deterioration, citing the sharp upward trend in AQI. Authorities have urged citizens to avoid using private vehicles, reduce dust-generating activities, and follow safety precautions such as wearing N95 masks when venturing outdoors.

The staggering of office hours and the shift to hybrid learning for schools aim to reduce peak-hour congestion and vehicular emissions, which are major contributors to Delhi’s pollution levels. Construction activities, another significant source of particulate matter, have also been halted, along with the operation of stone crushers and mining units.

Broader Context

The current episode adds to a long-standing challenge for Delhi, which has repeatedly faced hazardous air quality during the winter months due to a combination of vehicular emissions, industrial pollution, crop stubble burning in neighbouring states, and unfavourable weather conditions. Despite long-term efforts to curb pollution, episodes like these highlight the fragility of air quality management in the NCR region.

Experts point out that such high levels of AQI can cause serious respiratory issues, ranging from breathing discomfort to aggravated asthma, and can even affect healthy individuals with prolonged exposure.

Looking Ahead

With GRAP Stage-3 measures now in effect, the authorities aim to curtail further emissions and safeguard public health while closely monitoring the situation. Real-time AQI readings from multiple stations will guide the implementation of further interventions, and the CAQM has pledged continuous surveillance and enforcement of restrictions.

While temporary, these measures underscore the urgency of collective action from both the government and residents. Only through sustained compliance, reduced emissions, and strict monitoring can the capital hope to weather the ‘severe’ air quality episode and prevent similar crises in the future.

As Delhi grapples with its most polluted day of the season, the Stage-3 curbs serve as a reminder of the city’s vulnerability to extreme air pollution and the critical need for coordinated regional efforts to improve air quality in the National Capital Region.