Exclusive: Data links Punjab's fire spikes to Delhi's pollution within 24 hours

New Delhi: Delhi’s air is now moving in tandem with farm fires in Punjab. When stubble-burning cases in Punjab shoot up, Delhi-NCR’s air quality index (AQI) tends to jump into the “very poor” band within a day. When the burning slows, the air briefly improves. 

When the fires pick up again, the AQI climbs back. This pattern is clearly visible in daily data between October 16 and October 26.

In this chart, each date shows two bars. One bar is the number of stubble-burning incidents Punjab reported the previous day. The bar next to it is Delhi’s AQI on the following day. The idea is simple: does smoke in Punjab today show up in Delhi’s air tomorrow?

The trend is hard to ignore.

On October 19, Punjab recorded 67 stubble-burning incidents. The next day, on October 20, Delhi’s AQI jumped to 345. By October 21 and 22, Delhi was in the 351-353 range, firmly in the “very poor” band, which is 301-400 on the Central Pollution Control Board (CPCB) scale. 

AQI in this range means the air is unhealthy even for people without existing respiratory problems.

Gurugram, which sits downwind of Delhi, shows the same pattern, in fact, even sharper in places.

When Punjab’s fire count was high on October 19 and 20, Gurugram’s AQI spiked to 370 on October 21. That is deep in the “very poor” band. 

After that, when the fire numbers dipped, Gurugram’s air also eased. It fell to the 208-234 range between October 23 and October 25, which is still “poor” but no longer “very poor”.

Delhi behaved in a similar way. After peaking at 353 on October 22, Delhi’s AQI came down to 305 on October 23, 275 on October 24 and 292 on October 25, moving from “very poor” to “poor”. During this window, Punjab’s daily burning count also dropped sharply for a day, including a fall to 28 incidents on October 23. 

The data suggests that when stubble burning slows, the air in NCR starts to breathe, at least for a short period.

The relief did not last.

Punjab’s stubble-burning numbers climbed again on October 24 and 25 (49 and then 60 incidents). 

The next day, Sunday, October 26, Delhi slipped back into the “very poor” category with an AQI in the 320-plus range, and authorities again warned of stress on sensitive groups.

This cannot be explained only by local factors such as vehicle emissions, road dust and construction. Those sources are constant. What is changing, sharply and almost day-to-day, is farm fire intensity in Punjab. 

Transport forecasts during this period also pointed to north-westerly winds carrying smoke from Punjab towards Delhi, which means the stubble smoke is not just staying local, it is travelling into NCR.

This is also where the politics usually begins. Every winter, Delhi blames smoke blowing in from crop burning in Punjab and Haryana. State governments point back at Delhi’s own sources and demand action on local traffic, construction and fuel use. The Centre steps in with emergency curbs under the Graded Response Action Plan (GRAP). 

Courts monitor what is being enforced. Residents, meanwhile, are left to handle the health cost. 

The daily pairing of Punjab’s burn numbers and Delhi-NCR’s AQI does not end the argument, but it does tighten the timeline: the impact is often visible within 24 hours.

There is another claim that comes up every year that Punjab’s stubble-burning cases are “much lower than before”, and therefore cannot be the main reason Delhi’s air turns toxic. 

The claim that farm fire cases in Punjab have “dropped sharply” this year needs context. Punjab’s own remote-sensing data said the state saw a dramatic fall in reported stubble-burning incidents, from 36,663 farm fire events in 2023 to 10,909 in 2024, a drop of about 70 percent. 

But over the same period, the estimated paddy area that was actually burnt did not go down. In fact, it slightly went up: from 19.14 lakh hectares in 2023 to 19.17 lakh hectares in 2024. 

That tells you something important. If the number of “fires” is supposed to have collapsed, but the total land scorched by those fires stayed roughly the same, and even grew, then the fall in the headline figure is not necessarily proof that farmers stopped burning. 

It more likely reflects how incidents are being detected, labelled, and reported.

Officials in Punjab have already admitted that the counting process can miss fires. Satellite monitoring works in fixed passes a couple of times a day. 

If farmers burn outside those windows, the fire often doesn’t show up in the “incident” tally at all. There’s also a new layer of filtering: local teams now “verify” satellite alerts on the ground and strike off anything they classify as a false alarm. 

The end result is a cleaner-looking number for public consumption, but one that may no longer be comparable to older seasons where almost every hotspot was treated as a burning event.

The gap between “incidents logged” and “hectares actually burned” is the red flag. It suggests that official success stories, claims of huge percentage drops in stubble burning, can be driven as much by methodology and classification as by real change on the ground. Which is why comparing today’s stubble-burning count to last year’s and declaring victory is not a like-for-like comparison.

The day-wise comparison this season is not trying to prove absolute volume. It is showing a correlation: when there is a spike in these burn events, there is a spike in AQI in Delhi and Gurugram almost immediately; when the burning drops, the AQI eases.

Delhi was back in “very poor” again on October 26. If fires in Punjab keep climbing through late October and early November, the bar for Delhi and Gurugram will only move higher towards “severe” (AQI 401-500). In that band, CPCB warns of “respiratory effects even on healthy people” and “serious health impacts” on those with lung or heart disease.

In the meantime, people in Delhi are bracing for the familiar winter restrictions. With pollution rising, authorities are expected to move through phased GRAP measures, including tighter curbs on construction and, if conditions worsen, restrictions on private vehicles.