Smog Season Begins: 114 Farm Fires, Delhi AQI 129 — Stubble Burning Explained, Punjab To Pakistan | New-delhi-news News

Last Updated:October 01, 2026, 10:42 IST

Delhi’s AQI has turned moderate as farm fires begin to rise. But how much does stubble burning really add to the capital’s pollution, and what lies ahead?

NEW DELHI: Delhi’s air quality slipped into the moderate category on Wednesday, with the city recording an Air Quality Index (AQI) of 129 after five consecutive days in the satisfactory category. At the same time, satellite observations detected 19 crop-residue burning events across six states, including seven each in Punjab and Uttar Pradesh.

Between September 15 and 30, 114 residue-burning events were detected across Punjab, Uttar Pradesh, Madhya Pradesh, Haryana, Rajasthan and Delhi. Punjab accounted for 59 of these fires, followed by Uttar Pradesh with 32 and Madhya Pradesh with 17. Haryana recorded three, Rajasthan two and Delhi one.

The numbers are still far below the levels typically seen at the height of the burning season. But they mark the beginning of the annual period when farm fires, changing winds, falling temperatures and stagnant atmospheric conditions can combine to worsen air quality across northern India.

So, what exactly is stubble burning, why does it become a Delhi story every year, and could this season be any different?

What Is Stubble Burning?

Stubble burning, commonly called parali burning, is the practice of setting fire to crop residue left behind in agricultural fields after harvesting. In north-western India, the biggest post-monsoon concern is paddy residue. After rice is harvested, farmers are left with stalks and other material that must be cleared before the next crop – usually wheat – is sown.

Instead of removing or managing the residue mechanically, some farmers burn it directly in the field. The practice releases particulate matter, carbon monoxide and other pollutants into the atmosphere.

Crop-residue burning is not confined to one season. It also occurs after the rabi harvest, particularly in April and May. However, the October-November burning associated with paddy harvesting receives far greater attention because of its proximity to the Delhi-NCR airshed and the onset of winter meteorological conditions.

When Does Stubble Burning Begin In India?

The post-monsoon farm-fire season generally begins to pick up in late September and early October, although the exact timing varies with the progress of the harvest. It usually intensifies through October and reaches its peak around late October and November. The timing is closely linked to the short gap between paddy harvesting and sowing of the next crop.

This year, satellite detections were already being recorded in Punjab, Uttar Pradesh, Madhya Pradesh and Haryana by September 30. However, the current numbers should not be confused with the much larger fire counts that can occur later in the season.

Why Is The Window So Short?

The problem is partly rooted in the agricultural calendar. In Punjab and Haryana, restrictions designed to conserve groundwater pushed paddy transplantation later into the monsoon season. That can compress the period between harvesting rice and sowing wheat.

Farmers therefore face a narrow window in which fields have to be cleared and prepared for the next crop. Burning is quick and relatively inexpensive compared with alternatives, although it releases pollutants and causes other environmental damage.

Which States Are Affected?

Punjab and Haryana are traditionally at the centre of the Delhi-NCR stubble-burning debate, but crop-residue fires are not limited to these two states. Satellite data also routinely detect agricultural fires in Uttar Pradesh, Madhya Pradesh, Rajasthan and Delhi, among other parts of the country.

For the September 15-30 period this year, the six-state data cited by ICAR-IARI recorded:

Punjab’s 59 events account for just over half (51.8%) of the 114 detected events, followed by Uttar Pradesh with 32 and Madhya Pradesh with 17. The numbers show why Punjab and Uttar Pradesh are currently attracting attention, but they also underline that farm fires are a wider agricultural issue.

Why Does Delhi Make Headlines Every Year?

The simple answer is that Delhi sits downwind of a major agricultural belt at precisely the time of year when weather conditions become increasingly hostile to pollutant dispersion.

North-westerly winds can transport smoke from Punjab and Haryana towards Delhi and the wider Indo-Gangetic Plain. At the same time, cooler temperatures, lower wind speeds and atmospheric inversion can restrict vertical mixing and keep pollutants closer to the surface.

That creates what is effectively a dangerous combination: Farm Fires + Local Emissions + Weak Winds + Temperature Inversion = Rapidly Deteriorating Air

Stubble Burning Is Not The Only Reason Delhi Turns Polluted

Research does not support treating farm fires as the sole cause of Delhi’s winter pollution. Delhi has substantial local and regional sources, including vehicle emissions, road and construction dust, industry, waste burning and other combustion sources. Weather determines how efficiently these pollutants disperse.

One modelling study estimated that non-local crop-residue burning contributed around 20% of Delhi’s PM2.5 on average during October-November, but its contribution could rise to 50-75% during particular pollution episodes.

A newer 2025 study, however, found a much weaker relationship: it estimated that crop-residue burning in Punjab contributed about 14% of overall PM2.5 in Delhi-NCR during October-November 2022. The researchers cautioned that local sources, regional transport and weather also play major roles.

The takeaway is important: farm fires can significantly worsen particular pollution episodes, but Delhi’s air-quality crisis cannot be reduced to stubble burning alone.

Does Pakistan’s Air Quality Also Play A Role?

Yes, but it needs to be understood as part of a wider regional airshed rather than as a single external source of Delhi’s pollution. Punjab is a geographically continuous agricultural region on both sides of the India-Pakistan border. Crop burning and other emissions in Pakistan’s Punjab can therefore become part of the same regional pollution system.

Research using backward air-mass trajectories has identified air movements reaching Delhi from Punjab, Haryana and Pakistan during pollution episodes.

This means pollution does not respect international borders. But it would be inaccurate to attribute Delhi’s annual smog primarily to Pakistan. The relative contribution from different sources changes with wind direction, atmospheric conditions, fire intensity and local emissions.

Is Stubble Burning Only A North India Problem?

No. Crop-residue burning occurs across different agricultural regions of India, and its pollution can affect air quality at regional scales. However, the Delhi-NCR and Indo-Gangetic Plain problem is particularly severe because of the concentration of agricultural fires, the geography of the region and winter meteorology.

A 2026 study examining crop-residue burning across the Indo-Gangetic Plain found that the effect on regional air quality varies with cultivation patterns, meteorology and the location of burning.

Can Mumbai Be Affected By Farm-Fire Smoke?

Mumbai does not experience the same persistent north Indian smog pattern as Delhi, but it is not completely isolated from pollution transported over long distances. A study examining Mumbai’s unusually poor air quality in 2022-23 found that changes in atmospheric circulation were associated with stronger northerly winds at higher levels, potentially transporting pollution towards the western coast while weaker surface winds allowed pollutants to accumulate.

More recent reporting has also highlighted how agricultural burning in central and western India can coincide with poor air quality in Mumbai.

But this does not mean Delhi’s Punjab-Haryana stubble smoke routinely blankets Mumbai. Mumbai has its own major pollution sources, including traffic, construction and dust, industry and local biomass burning. Long-range transport can add to the pollution burden under particular weather conditions.

What About Bengaluru?

Bengaluru is considerably farther from the principal north-western crop-burning belt and has a different geography and atmospheric circulation. It can experience poor air quality, but its pollution is generally driven much more by local and regional sources such as traffic, dust, construction and other urban emissions.

There is therefore no basis for treating Bengaluru’s winter air-quality problem as equivalent to Delhi’s seasonal stubble-burning episode.

Will This Year’s Rains Make The Air Cleaner?

Not necessarily. Rain can temporarily improve air quality by removing particulate matter from the atmosphere. Delhi’s recent cleaner-air days have benefited from favourable weather, including rainfall. But rain earlier in the season does not guarantee cleaner air during the peak crop-burning period.

In fact, heavy rainfall can complicate the agricultural calendar by affecting crop maturity and harvesting. If harvesting is delayed, the period available to prepare fields for the next crop can become more compressed, potentially concentrating burning into a shorter window.

There is also an important 2026 weather development: India’s southwest monsoon ended with rainfall about 13% below the long-period average, making it the country’s driest monsoon in 11 years, according to the IMD.

So, the assumption that this year’s rains will automatically translate into a cleaner stubble-burning season is not supported by the available evidence.

Do Diwali Firecrackers Add To The Problem?

Yes. Firecrackers release large amounts of particulate matter and gaseous pollutants over a short period. Their impact can be especially pronounced when Diwali coincides with stagnant atmospheric conditions and an already elevated pollution load.

A peer-reviewed study examining Delhi’s air quality found that firecracker activity significantly increased particulate concentrations over a relatively short period. The researchers estimated roughly a 100% increase in PM2.5 and a 55% increase in PM10 associated with firecracker activity during the period studied.

Another study examining Diwali pollution across 14 cities in the Indo-Gangetic Basin found substantial increases in particulate pollution during the festival period, with meteorological stagnation amplifying the effect.

This does not mean Diwali is the cause of the entire winter pollution crisis. Rather, firecrackers can add a sharp, short-term pollution spike to an atmosphere already carrying pollutants from multiple sources.

When Could Delhi’s AQI Get Worse?

The first signs are already visible, but the most difficult period usually comes later. Delhi’s AQI was 129 on September 30, putting it in the moderate category. The Air Quality Early Warning System has forecast moderate conditions for October 1-3 and the following days, although the situation can change rapidly with wind and weather.

Historically, late October through November is the period when the risk of severe pollution episodes rises sharply, as farm-fire activity increases and winter meteorological conditions become more conducive to pollution accumulation.

The exact date of the next major deterioration cannot be predicted months in advance because it depends heavily on day-to-day weather and fire activity.

The Seasonal Pollution Clock

This is a seasonal guide, not a forecast for specific AQI levels.

What Should Delhi-NCR Residents Do?

The most useful response is to follow the actual AQI rather than assume that every day in October or November will be hazardous. When pollution levels rise:

• Check the daily AQI and local pollution advisories, particularly before prolonged outdoor activity.
• Reduce strenuous outdoor exercise when AQI moves into poor or worse categories.
• People with asthma, heart or lung disease, older adults and children should take particular care during pollution episodes.
• Keep windows closed during severe outdoor pollution, while ensuring indoor air is adequately ventilated when outdoor conditions improve.
• Consider using a properly fitted N95/N99 respirator during severe pollution if prolonged outdoor exposure is unavoidable.
• Avoid adding to indoor pollution through smoking, incense, mosquito coils and unnecessary burning.
• Use public transport or car-pooling where practical, particularly during peak pollution episodes.
• Follow official restrictions on construction, vehicle use, firecrackers and other activities when emergency pollution-control measures are activated.

The Bigger Picture: Delhi’s Smog Is Not Just A Farm-Fire Story

The annual focus on stubble burning is understandable: satellite images of hundreds or thousands of farm fires provide a highly visible source of pollution, and studies have established that smoke can travel towards Delhi under favourable wind conditions. But Delhi’s winter air is the product of a much larger system.

Farm fires produce emissions. Local vehicles and other sources add more. Weak winds slow dispersion. Temperature inversions trap pollutants. Dust and secondary pollutants add to the burden. Firecrackers can create a short, intense spike.

That is why two days with similar numbers of farm fires can produce very different AQI readings in Delhi.

The current numbers are therefore an early warning rather than a prediction of the winter ahead. With Delhi already moving from satisfactory to moderate air quality and the farm-fire season beginning, the next few weeks – particularly the timing of the paddy harvest, the number of fires and the weather over the Indo-Gangetic Plain – will be crucial in determining how quickly the capital’s air deteriorates.

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