Delhi’s air quality index reached 350 on Tuesday, its worst reading in 287 days. Ten monitoring stations were in the “severe” band. On the same day Punjab recorded 584 farm fires, the highest single-day count of the season. With forecasters predicting still worse air later this week, the annual winter pollution crisis has arrived, with crop-residue burning one significant contributor among several.
For Delhi’s 20-million-plus residents, the first week of November has a grim predictability. On Tuesday, the city’s 24-hour average air quality index (AQI) reached 350, firmly “very poor” and the worst since 20 January, when it touched 378, PTI reported. It had been 324 a day earlier and 117 on 31 October.
The averages hide worse readings. Of the city’s 57 monitoring stations, ten recorded “severe” air, above 400 on the national scale. Jahangirpuri was worst at 462, followed by Punjabi Bagh at 445 and Rohini at 442. A further 35 stations were “very poor” and 12 “poor”.
What the index means
India’s national AQI converts concentrations of several pollutants, chiefly fine particulate matter (PM2.5), into a single number from 0 to 500. Readings of 301–400 are “very poor” and are associated with respiratory illness on prolonged exposure. Readings above 400 are “severe”, affecting healthy people and seriously affecting those with heart or lung disease. PM2.5 particles are less than 2.5 micrometres across, small enough to reach deep into the lungs and enter the bloodstream. The World Health Organization’s annual guideline for PM2.5 is 5 micrograms per cubic metre; Delhi’s winter levels routinely run many times higher.
Where the pollution comes from
The Centre’s Decision Support System, a modelling tool run by the Indian Institute of Tropical Meteorology for the Commission for Air Quality Management (CAQM), estimated on Tuesday that:
- Stubble burning contributed 15.3% of Delhi’s pollution load
- Transport contributed 15.8%
The remainder comes from industry, construction dust, waste burning, household fuel and pollution from neighbouring towns. Weather turns these emissions into a crisis. As temperatures fall, cooler air settles under a layer of warmer air, an inversion that acts like a lid. Low wind speeds then allow pollutants to accumulate rather than disperse.
Punjab’s fires
In Punjab, satellites and state monitoring recorded 584 farm fires on 3 November, The Tribune reported, against 256 on the same date in 2025 and 216 in 2024. The districts with the most were Ferozepur (112), Bathinda (80), Sangrur (78) and Tarn Taran (56).
The figure needs context. It is the season’s highest single-day count, not an all-time record. Punjab’s cumulative season total of 2,196 fires remains below the 2,518 recorded by the same point last year, and far below the counts of a decade ago. The rise this week may reflect the timing of the paddy harvest as much as any change in behaviour. Farmers clearing fields quickly for wheat sowing, with a narrow window between crops, still find burning the cheapest option despite subsidised residue-management machines and in-field decomposers.
Why the burning window keeps narrowing
Part of the problem is an unintended result of water policy. Punjab’s 2009 law on preserving subsoil water delays paddy transplanting until mid-June, to reduce groundwater pumping in the hottest months. That has saved water, but it has also pushed the harvest later, into late October and November. Researchers have linked this shift to fires that now coincide with the cooler, calmer weather in which smoke lingers over the plains. Long-duration paddy varieties make the squeeze worse, because they leave only a short gap before wheat must be sown.
The alternatives are known, but each has costs:
- In-field management: machines such as the Happy Seeder and Super Seeder sow wheat directly through the stubble, and microbial decomposer sprays break residue down.
- Off-field use: straw can be baled for use in biomass power, compressed biogas and second-generation ethanol plants, or co-fired with coal in thermal power stations.
- Crop choice: shorter-duration paddy varieties widen the window between harvest and sowing.
All of these depend on machines arriving at the right farm in a two-to-three-week window, and on supply chains that pay farmers enough to make collecting straw worthwhile.
The Punjab Pollution Control Board also dismissed private-app AQI readings for Bathinda as high as 737 as unreliable. That is a reminder that only calibrated, regulatory-grade monitors should be used to judge air quality.
The policy response
The CAQM invoked Stage II of the Graded Response Action Plan (GRAP) on 2 November. It restricts diesel generators, bans coal and firewood in eateries and intensifies dust control. The government’s Air Quality Early Warning System forecasts “very poor” air from 4 to 6 November and possibly “severe” after that. If the AQI crosses 400, Stage III would bring curbs on construction and on older petrol and diesel vehicles. NSH found no report that the CAQM is yet considering it.
GRAP is an emergency brake, not a cure. Air-quality scientists have long argued that Delhi’s winter peaks cannot be solved by seasonal restrictions alone. Year-round reductions are needed in vehicle, industrial, construction and household emissions across the whole Indo-Gangetic Plain. Pollution does not stop at the borders of Delhi.
Why this matters beyond Delhi
The burden falls hardest on children, older people, outdoor workers and those with asthma or heart disease. Large epidemiological studies have linked long-term exposure to fine particles in India with substantial excess mortality, though estimates vary with method. Hyderabad and Visakhapatnam enjoy cleaner winters thanks to geography and wind, but they too face rising traffic, construction and industrial emissions, and they cannot assume they are immune.
