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हिन्दी — Read in HindiAir pollution
The National Clean Air Programme and the sources of polluted air, from vehicles and power plants to crop burning, dust and indoor fuel. Prelims has asked which gases are used to calculate the Air Quality Index and about the World Health Organization (WHO) air quality guidelines.
Foundation notes: The Graded Response Action Plan · Air quality: the standards and the index
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GRAP and Delhi's winter plan, 2026
Copy link to GRAP and Delhi's winter plan, 2026Prelims and Mains
LeadDelhi's winter air: the revised GRAP and a fixed calendar of curbsSeptember 2026
Why in news
On 28 September 2026 CAQM approved a revised GRAP schedule, and Delhi announced a winter plan with curbs fixed by date from 1 November 2026 to 31 January 2027.
Background
- GRAP has four stages tied to the Air Quality Index: Stage I at 201 to 300 (poor), Stage II at 301 to 400 (very poor), Stage III at 401 to 450 (severe) and Stage IV above 450 (severe plus).
- Each stage adds to the one below, and a stage can be invoked on a forecast, before the reading crosses its band.
- In winter, falling temperatures trap vehicle exhaust, industrial emissions and crop residue smoke close to the ground.
What changed in GRAP
- Curbs on diesel generator sets and on the entry of buses of BS IV and below moved up from Stage II to Stage I.
- The exemption for goods vehicles of BS IV and below carrying essential commodities in Stages III and IV was removed.
- Dust monitoring of construction sites was extended beyond municipal limits to industrial and highway corridor zones.
Delhi's fixed calendar
- From 1 November to 31 January dust generating construction stops, parking charges double, offices stagger their hours and up to half the staff work from home.
- All construction and demolition is banned from 10 December to 20 January.
- From 1 November vehicles below BS VI registered outside Delhi are barred, with compressed natural gas and electric vehicles exempt.
- From 1 October a vehicle without a valid Pollution Under Control Certificate gets no fuel in the region.
The farm fire side
- CAQM has directed Punjab, Haryana and Uttar Pradesh to eliminate paddy stubble burning in 2026.
- A strong El Niño is expected to bring fewer rain bearing Western Disturbances, so the air will clear less often this winter.
GRAP stages, as revised in September 2026
| Stage | Air Quality Index | Air quality | Actions |
|---|---|---|---|
| I | 201 to 300 | poor | 25 |
| II | 301 to 400 | very poor | 8 |
| III | 401 to 450 | severe | 10 |
| IV | above 450 | severe plus | 5 |
The way forward
- A fixed calendar gives residents and businesses notice, which graded curbs never did, but it treats the season and not the sources.
- Vehicles are the largest primary source of Delhi's winter pollution, at about 23 per cent, so cleaner transport matters more than seasonal bans.
- Municipal and even regional boundaries are too small for the problem, which is the case for managing the whole airshed.
Prelims facts
- GRAP stages follow the Air Quality Index: 201, 301, 401 and above 450.
- CAQM is a statutory body and acts through directions that the States must enforce.
- The airshed approach manages air quality across a shared geographic area and not within administrative boundaries.
- BS VI norms, in force nationwide since 2020, set stricter limits on nitrogen oxides and particulate matter.
The Graded Response Action Plan (GRAP) is the set of emergency curbs for Delhi and the National Capital Region that switch on in four stages as the Air Quality Index worsens.
- It is run by the Commission for Air Quality Management (CAQM), a statutory body under an Act of 2021.
- Its curbs arrive only when the air has already turned bad, so Delhi has added a winter plan that fixes restrictions by calendar date.