New Delhi, January 18, 2026:
Delhi’s air quality slipped into the “severe” category on Saturday night, prompting the Commission for Air Quality Management (CAQM) to invoke GRAP Stage 4 emergency measures. The city’s Air Quality Index (AQI) surged from 354 at 4 pm on Friday to 400 by 4 pm on Saturday, before spiking further to 434 by 11 pm—the worst reading since December 14 and the first “severe” air day since December 29.

CAQM said the sharp deterioration was driven by calm winds, a stable atmosphere, and unfavourable meteorological conditions, which trapped pollutants near the surface. An urgent meeting of the GRAP sub-committee was convened at 8:15 pm on Saturday as levels continued to rise.

What GRAP Stage 4 Means

With Stage 4 in force:

• Entry of BS-IV trucks into Delhi is restricted
• All construction and demolition activities are prohibited
• Schools up to Class 10 shift to hybrid mode, with only Classes 10 and 12 continuing in-person classes

These measures come on top of Stage 3 restrictions imposed on Friday, which include:

• Ban on BS-III petrol and BS-IV diesel four-wheelers across Delhi-NCR districts (Delhi, Gurugram, Faridabad, Ghaziabad, Gautam Budh Nagar)
• Blanket curbs on private construction and demolition
• Restrictions on stone crushers and mining
• Hybrid schooling for Classes up to 5 in Delhi and neighbouring areas

Weather Behind the Spike

According to the IMD, warm easterly winds, very low wind speeds (3–4 kmph), and high humidity (53%–100%)worsened pollution levels. “Pollutants stick to water vapour, become heavier, and accumulate near the ground,” said Mahesh Palawat of Skymet Weather. Wind speeds are expected to improve over the next two days.

What’s Next?

The Air Quality Early Warning System forecasts “severe” air quality through Sunday, easing to “very poor” from Monday to Tuesday, and potentially improving to poor later in the week.

Fog Disruptions

Moderate to dense fog enveloped parts of the Capital on Saturday morning:

• Palam: Visibility dipped to 350 m at 6:30 am
• Safdarjung: Fell to 250 m by 7:30 am, and 200 m at 9:10 am

More than 550 flights were delayed at Delhi airport on Saturday. IMD has issued a yellow alert for Sunday, warning of moderate to dense fog in early hours.

Temperature Update

The minimum temperature stood at 4.4°C on Saturday—3.2°C below normal. IMD forecasts 4–6°C on Sunday and 6–8°C on Monday.

AQI Categories (CPCB):

• Moderate: 101–200
• Poor: 201–300
• Very Poor: 301–400
• Severe: 401+

Under GRAP, Stage 4 is triggered when AQI approaches the severe threshold, requiring the strictest curbs to protect public health.