Making it more difficult for Delhiites to breathe easy, amid the bone-chilling cold, the national capital's average air quality index on Saturday evening slipped into 'severe' category, recording an index value 416 at 6 pm, according to the Central Pollution Control Board (CPCB).

The average AQI recorded during the day was 400, as per the daily bulletin released by the CPCB at 4 pm, however, it witnessed further deterioration, as the numbers climbed.

As compared to Friday's average, the spike witnessed on Saturday was initially of 46 points, which gradually increased further, most likely due to the low wind speed and unfavorable meteorological conditions for the dispersal of the pollutants.

The primary pollutants affecting the city's air were the PM 2.5 particles, according to the pollution monitoring agency.

The Commission for Air Quality Management in Delhi and NCR had already invoked actions under its Graded Response Action Plan's stage- III on Friday, so as to prevent the air quality from further deterioration.

The worst affected areas in terms of spiked AQI levels at 6 pm include Anand Vihar, 483, Dwarks Sec 8- 460, Wazirpur- 459, Vivek Vihar- 458, Mundka- 456, and Nehru Nagar- 453.

As per the Indian Institute of Tropical Meteorology (IITM), "The air quality is likely to be in the Severe category from 17.01.2026 to 18.01.2026. The air quality is likely to be in the Very Poor category from 19.01.2026 to 20.01.2026."

Air quality under the 'severe' category affects healthy people and seriously impacts those with existing diseases, especially the elderly and children.

Meanwhile, intense cold was also experienced in the morning hours with minimum temperature recorded at 4.4 degrees C, which was 3.2 notches below season's normal.

The India Meteorological Department (IMD) has issued a yellow alert for Sunday with forecast of a partly cloudy sky, moderate fog at many places and dense fog at isolated places in the morning hours.

The CAQM is continuously monitoring the air scenario, and in case the air quality deteriorates further, it may think of invoking the GRAP- IV measures across the city, in a bid to prevent the pollution situation from escalating further.

Previously, on December 13, 2025, the AQI of Delhi had soared to 431 at 4 pm, and had exhibited an increasing trend recording 441 at 6 pm, owing to slow wind speed, stable atmosphere, and unfavorable weather parameters, and the sub-committee had invoked GRAP- IV measures, in addition to the already implemented I, II and stage- III actions. This was revoked on December 24, 2025 after an improvement was witnessed.

As per CPCB standards, an AQI between 0 and 50 is considered 'good', 51-100 'satisfactory', 101-200 'moderate', 201-300 'poor', 301-400 'very poor', and 401-500 'severe'.