Delhi's Air, October 2026: How GRAP Works and Why Stage II Arrived Early

Delhi's 24-hour average air quality index reached 312 on 15 October 2026, the first "very poor" reading of the season, and the Commission for Air Quality Management invoked Stage II of the Graded Response Action Plan the same evening. The commission's forecast put PM2.5 at 148 micrograms per cubic metre and PM10 at 286 for the next two days [1][2].

The timing is early but not surprising. A dry September, a late monsoon withdrawal and a sharp drop in night-time temperature have combined to trap pollutants near the ground, while paddy stubble fires in Punjab and Haryana are beginning to climb. What follows is how the emergency framework works, and why it is a response to the symptom rather than the disease [1][3].

The numbers

• AQI, 24-hour average: 312, in the "very poor" band, against 214 on 10 October [2].
• PM2.5: 148 micrograms per cubic metre, nearly five times the national annual standard of 40 [2].
• PM10: 286 micrograms per cubic metre, against a standard of 100 [2].
• Stubble fires: 1,842 counted in Punjab between 1 and 15 October, 12 per cent more than the same period last year [3].
• Weather: wind speed below 5 kilometres per hour at night, a mixing height of about 400 metres, and no rain forecast for a week [4].

What GRAP is

The Graded Response Action Plan is a set of emergency measures that kick in as the air quality worsens. It was first notified in 2017, was implemented by the Environment Pollution (Prevention and Control) Authority until 2021, and is now run by the CAQM under the Commission for Air Quality Management Act, 2021 [1][5].

Stage	AQI trigger	Headline measures
Stage I, Poor	201 to 300	Dust control, mechanised sweeping, water sprinkling, strict checks on construction sites
Stage II, Very Poor	301 to 400	Coal and firewood banned in eateries, diesel generator restrictions, higher parking fees, more bus services
Stage III, Severe	401 to 450	Non-essential construction halted, BS-III petrol and BS-IV diesel cars banned, mining and stone crushers stopped
Stage IV, Severe Plus	Above 450	Entry of trucks restricted to essentials, odd-even considered, schools closed, emergency measures

The stages are cumulative, so Stage II carries Stage I measures with it. The triggers are based on the 24-hour average AQI and on the forecast, which is why an order can arrive before the number crosses the threshold [1][4].

Why October is the hinge

Delhi's air has three sources and a seasonal amplifier.

• Local sources. Vehicles contribute roughly a fifth of PM2.5, road dust a similar share, and industry and waste burning the rest. These operate all year.
• Regional sources. Stubble burning in Punjab, Haryana and western Uttar Pradesh adds a burst of PM2.5 in October and November, carried into Delhi by north-westerly winds.
• Secondary formation. Nitrogen oxides and sulphur dioxide from vehicles and industry react in the atmosphere to form secondary aerosols, which are a large share of winter PM2.5.
• The amplifier. A shallow inversion layer, low wind speed and a low mixing height trap everything near the ground. In summer, the same emissions disperse [4][6].

The festival calendar adds a spike. Diwali falls on 8 November 2026, later than usual, which means the firecracker night will coincide with the stubble season rather than precede it [4].

"The Commission hereby invokes Stage II of the Graded Response Action Plan with immediate effect."

That is the operative sentence in the CAQM order of 15 October. It is a familiar one; the question each year is whether the measures are enforced after the order is issued [1].

The stubble question

Stubble burning is the most visible and the most misunderstood part of the problem.

• Why farmers burn. The window between paddy harvest and wheat sowing is about three weeks. Residue removal costs money, and the machines that do it are expensive to hire.
• What has worked. The Crop Residue Management scheme subsidises happy seeders, super seeders and balers. Punjab's 2026 incentive of ₹2,500 per acre for not burning has improved compliance in the districts where it has been paid on time [3].
• What has not. Compensation delays, the cost of diesel, and the lack of a market for paddy straw keep burning cheaper than the alternatives. The bio-decomposer sprayed on fields is effective but slow.
• The scale. Even a 40 per cent reduction in fires would not solve Delhi's air, because local and regional sources outside the farm sector contribute more in aggregate [3][6].

The long-run fixes

The National Clean Air Programme, launched in 2019, set a target of reducing PM2.5 and PM10 by 40 per cent by 2025-26 in 130 non-attainment cities. Delhi's own plan rests on five shifts.

• Transport. Fleet electrification, more buses and metro expansion. Delhi's bus fleet crossed 7,500, including more than 2,000 electric buses, but the metro's share of trips has plateaued [6].
• Dust. Mechanised road sweeping, water sprinkling and construction-site rules. Enforcement is the weak link, because the number of sites is large and the inspection staff small.
• Industry. A shift to cleaner fuels, with PNG mandated in industrial areas and coal banned in the NCR.
• Waste. A ban on open burning and the closure of landfill fires, which are a significant winter source.
• Regional coordination. The CAQM's jurisdiction over Delhi, Haryana, Punjab, Rajasthan and Uttar Pradesh is the institutional answer to a problem that does not respect state borders [5][6].

The enforcement question

The CAQM Act gives the commission wide powers: it can issue directions, impose penalties up to ₹1 crore, and recommend prosecution. The Supreme Court has repeatedly pushed for stricter implementation in the M.C. Mehta case, and has criticised the gap between the orders and the outcomes [5][7].

• The capacity gap. A few hundred inspectors cannot monitor thousands of construction sites and industrial units.
• The political economy. Stubble burning is a livelihood issue in states where farm votes matter, and vehicle restrictions impose costs on commuters.
• The accountability gap. GRAP is an emergency protocol, not a clean air plan. Its measures are temporary by design, and the air returns to its baseline once the weather changes.

Quick answers

What is GRAP? The Graded Response Action Plan, a set of emergency measures triggered by AQI thresholds, implemented by the CAQM under the 2021 Act [1][5].

What triggered Stage II in October 2026? Delhi's 24-hour average AQI reached 312 on 15 October, in the "very poor" band, with calm winds and a low mixing height [1][2].

What are the four stages? Poor (201-300), Very Poor (301-400), Severe (401-450) and Severe Plus (above 450), each with progressively stricter measures [1].

Why is stubble burning not the whole story? Vehicles, road dust, industry and secondary aerosol formation contribute more in aggregate across the winter, and weather determines how much of any source stays near the ground [6].

What is the NCAP target? A 40 per cent reduction in PM2.5 and PM10 by 2025-26 in 130 non-attainment cities, against the 2017 baseline [6].

What is the exam takeaway? Know the AQI categories, the four GRAP stages and their triggers, the CAQM's statutory basis, and the difference between emergency measures and the long-run clean air plan.

Sources

1. Commission for Air Quality Management: Order invoking Stage II of the Graded Response Action Plan. 15 October 2026. https://caqm.nic.in
2. Central Pollution Control Board: National Air Quality Index, Delhi stations, 15 October 2026. https://cpcb.nic.in
3. Punjab Remote Sensing Centre: Paddy residue burning events, 1 to 15 October 2026. https://www.prsc.gov.in
4. India Meteorological Department: Delhi forecast and mixing height bulletin, October 2026. https://mausam.imd.gov.in
5. Government of India: Commission for Air Quality Management in National Capital Region and Adjoining Areas Act, 2021. https://legislative.gov.in
6. Ministry of Environment, Forest and Climate Change: National Clean Air Programme, progress report 2026. https://moef.gov.in
7. Supreme Court of India: M.C. Mehta v. Union of India, orders on air quality, 2024-2026. https://main.sci.gov.in