Delhi AQI worsens to 323, IIT-Delhi records severe air quality as farm fires persist

Unfavourable meteorological conditions have played a significant role in the deterioration of Delhi's air quality.

Delhi's air quality deteriorated further on Thursday, with the Air Quality Index (AQI) climbing to 323 in the morning and remaining in the 'very poor' category, as calm winds and unfavourable meteorological conditions trapped pollutants close to the ground overnight.

The Central Pollution Control Board's (CPCB) hourly data recorded an AQI of 321 at 7am, which rose to 323 an hour later. (HT Photo)

The Central Pollution Control Board's (CPCB) hourly data recorded an AQI of 321 at 7am, which rose to 323 an hour later. This was eight points higher than Wednesday's official daily average of 313.

IIT-Delhi records worst air quality

Of the 57 air quality monitoring stations in the city, IIT-Delhi recorded the worst air quality, with an AQI of 414 in the 'severe' category. The Cantonment station was the only one to record 'moderate' air quality, with an AQI of 128. The remaining stations reported 'very poor' air quality.

PM2.5 remained the dominant pollutant, emerging as the leading contributor at 48 of the 57 monitoring stations, indicating high concentrations of fine particulate matter in the city's air.

The CPCB classifies an AQI of 0-50 as 'good', 51-100 as 'satisfactory', 101-200 as 'moderate', 201-300 as 'poor', 301-400 as 'very poor' and 401-500 as 'severe'.

Warmer nights, calm winds add to pollution woes

Delhi recorded a rise in minimum temperatures across all five weather stations on Thursday, with the mercury settling between 16°C and 17°C, significantly above the seasonal average, according to India Meteorological Department (IMD) data.

Palam recorded the lowest minimum temperature at 16°C, which was 1.8°C above normal. At Safdarjung, Delhi's base weather station, the minimum temperature settled at 16.5°C, 3°C above normal. Lodhi Road recorded a minimum of 16.6°C, 4.6°C above normal, the highest departure among the five stations.

The Ridge recorded a minimum of 17°C, 1.6°C above normal, while Ayanagar's minimum stood at 16.6°C, 2.1°C above the seasonal average.

Minimum temperatures also rose across all five stations compared with Wednesday. Safdarjung and Lodhi Road recorded an increase of 1.7°C each, followed by the Ridge at 1.4°C, Palam at 0.8°C and Ayanagar at 0.5°C.

Shallow fog affected visibility at Safdarjung and Palam during the morning hours. At Safdarjung, visibility dropped to 800 metres between 6.30am and 8am before improving to 900 metres at 8.30am. At Palam, visibility stood at 800 metres between 7.30am and 8am, improving to 1,000 metres by 8.30am. No rainfall was recorded at any of the five weather stations.

Unfavourable meteorological conditions have played a significant role in the deterioration of air quality. Calm winds overnight prevented pollutants from dispersing, while a layer of warmer air above the ground restricted vertical mixing, trapping pollution closer to the surface.

Farm fires add to pollution load

Stubble burning in neighbouring states remains another seasonal contributor to Delhi-NCR's pollution. However, the extent of its contribution depends on wind direction and speed, as well as the prevailing weather conditions.

According to a Hindustan Times report published on November 5, Punjab recorded 2,347 farm-fire incidents until November 4, compared with 2,839 during the corresponding period last year, marking a decline of 17.3%. Eleven of the state's 23 districts reported an increase in incidents.

However, the figures need to be viewed in context: burning has shifted to later hours each year. In 2025, 98% of the fire heat recorded by Meteosat came after 3 pm, compared with 94% in 2024. The two counts could therefore differ for this reason alone.

Both figures are undercounts, as most of the burning now takes place after the satellite passes over the region at around 1.30 pm.

Alongside stubble burning, vehicular emissions and other local pollution sources continue to add to the city's pollution burden. The combination of these emissions, weak winds and unfavourable atmospheric conditions makes it difficult for pollutants to disperse, particularly during the winter months.