Delhi’s AQI crossed 300 for the first time this season, entering the “very poor” category. Meteorologist Navdeep Dahiya said, “Most AQI sensors across Delhi NCR are now reporting AQI levels above 300.” Unfavourable weather conditions and farm fires mean the smog will likely worsen across the region in coming days.

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”.

PM2.5 primary pollutant

At 6 am on Monday, CPCB listed PM2.5 as the primary pollutant at 51 of the 58 reporting stations and PM10 at the remaining seven. At the same time a day earlier, PM2.5 was the main pollutant at 46 of 57 stations, while PM10 was recorded at 11.

Delhi last recorded “very poor” air quality on February 11 this year, when the 24-hour average AQI stood at 305. Before that, the AQI had reached 339 on February 4.

The rise in pollution levels comes a week ahead of Diwali, when firecracker bursting typically adds to the pollutant load in the Capital’s air.

Meanwhile, satellite data from NASA detected 1,394 farm fires in Punjab and Haryana between October 1 and November 1, 1,249 in Punjab and 145 in Haryana. Of these, 171 were recorded on November 1. During the same period last year, the satellite detected 1,861 fires.

To be sure, the figures may not be directly comparable, as stubble burning has increasingly shifted to later hours of the day. About 98 per cent of the fire heat recorded by Meteosat in 2025 came after 3 pm, compared with 94 per cent in 2024. Both years' figures are likely to be undercounts, as most burning now takes place after the satellite's pass at around 1.30 pm.

Air pollution to worsen in coming days

Meteorologist Navdeep Dahiya warned that the smog season had begun, with unfavourable weather conditions likely to worsen pollution levels in the coming days.

“Most AQI sensors across Delhi NCR are now reporting AQI levels above 300 and many are climbing the 400-500 range tonight. The flow of winds are from the north west with calm conditions. All emissions will persist in the atmosphere for longer duration,” he said in a post on X.

Dahiya added that no favourable meteorological conditions were expected over the next seven to 10 days, warning that smog would worsen across Delhi-NCR and the northern plains.