Delhi's air emergency: Why national capital chokes year after year — Stubble burning link explained

A farmer burns stubble after a harvest at a paddy field, on the outskirts of Amritsar. (PTI photo)

It’s that time of the year again — when Delhi turns into a gas chamber, gasping for breath under a thick toxic haze. The national capital slips into an annual air emergency as pollution levels soar and the Air Quality Index (AQI) plunges to hazardous lows.

While multiple factors fuel this crisis, stubble burning in neighbouring states remains a leading culprit, accounting for over 30 per cent of Delhi-NCR’s pollution in 2024. Add to this the relentless vehicular emissions and unfavourable weather conditions that trap pollutants in the air, and the capital finds itself suffocating in a recurring nightmare.

What is stubble burning?

Stubble (parali) burning is a method of removing paddy crop residues from the field to sow wheat from the last week of September to November. Stubble burning is a process of setting on fire the straw stubble, left after the harvesting of grains, like paddy, wheat, etc. It is usually required in areas that use the combined harvesting method which leaves crop residue behind.

The process of burning farm residue is one of the major causes of air pollution in parts of north India, deteriorating the air quality.

Punjab, Haryana, and Uttar Pradesh are the primary states where this practice is prevalent during this time of year.

Impact of stubble burning

Though cheaper and faster in the interim, stubble burning is incredibly unsustainable for the environment – it fills the air with soot, dispels nutrients out of the soil, and leads to several other ecological complications. Here's a list of the hazards:

• Contribution to atmospheric pollution: Stubble burning is a significant contributor to atmospheric pollution, coming in 3rd after industrial and vehicular emissions.
• Human health impacts: Several health effects have been noticed that arise from the resultant air pollution, ranging from skin and eyes irritation to severe neurological, cardiovascular, and respiratory diseases.
• Detrimental to the soil’s health: It strips soil of its essential nutrients such as nitrogen, phosphorus, and potassium (NPK). It also raises soil temperature to about 42°C, thus displacing or killing important microorganisms up to a depth of about 2.5 cm.

• Though stubble burning is cheaper than alternative disposal methods, it leads to severe air pollution. In order to prevent farmers from opting for this method, earlier in March 2025, a parliamentary standing committee recommended introducing a minimum support price (MSP) for paddy residue to discourage stubble burning.
• The recommendations were made by the Committee on Subordinate Legislation which examined the Commission for Air Quality Management (CAQM) in National Capital Region and Adjoining Areas (Imposition, Collection and Utilization of Environmental Compensation for Stubble Burning) Rules, 2023.
• In-situ crop residue management: It involves machines procurement, setting up of Custom Hiring Centers (CHCs), high yield and short duration paddy varieties, staggering of harvesting schedule, extensive use of bio-decomposer.
• Ex-situ crop residue management: Alternative usage of paddy straw viz. Biomass Power Projects, Co-firing in Thermal Power Plants, Feed stock for 2G Ethanol plants, Feed stock in Compressed Biogas plant, packaging materials etc.
• Prohibition of stubble residue burning: Through effective monitoring, enforcement Schemes to reduce the generation of paddy straw as well as imposition of environmental compensation from the farmers causing air pollution by stubble burning.
• Financial support mechanisms: Sub-Mission on Agriculture Mechanization (SMAM) provides financial assistance for procurement of agricultural machinery and equipment to small and marginal farmers.
• Promotion of alternatives: Like Bio Enzyme-PUSA, Palletization, Happy Seeder machine, utilization of biomass for Biofuel Production etc.

Unfavourable meteorological conditions, such as low wind speeds, temperature inversions, and stagnant air, trap pollutants from stubble burning and other sources near the ground, significantly worsening air pollution in Delhi during the winter months.

Stagnant winds and the resulting temperature inversions create a "lid" that prevents smoke and other particulate matter from dispersing, leading to thick smog and elevated air quality index (AQI) levels.