🐅 Environment
Delhi's air is the worst of the big metros as winter pollution season begins
In 60 seconds: Delhi's air quality index stood between 175 and 197 on Tuesday, the 'moderate' range but close to 'poor', making it the most polluted of India's four big metros, according to Central Pollution Control Board data. Stage 1 of the Graded Response Action Plan has been in force across Delhi-NCR since 21 October, as winter pollution builds up.
Why it matters
Polluted air harms lungs and hearts, especially for children and older people. Delhi's air usually gets much worse in November.
Explain it simply
In a small kitchen with the windows shut, smoke from the stove hangs in the air. On calm, cold days, Delhi is like that kitchen: smoke and dust have nowhere to go.
The 3-minute read
What happened
A morning CPCB reading put Delhi's AQI at 175. A later reading reported 197, the highest among Delhi, Mumbai, Kolkata and Chennai, where Chennai was 143.
Background
GRAP sets out steps in four stages as air worsens. Stage 1 applies when AQI is 'poor' (201–300) or expected to be, with measures such as dust control at construction sites and limits on open burning.
How it works
Calm winds and falling temperatures in late October trap pollution near the ground. Vehicle exhaust, construction dust and smoke from crop and waste burning add to it.
What's next
If AQI crosses 300, CAQM can move to Stage 2, with stricter curbs. Watch the daily forecasts through November.
What it means for you
On high-pollution days, limit outdoor exercise, keep children indoors in the morning and consider an N95 mask.
Key numbers
- 175–197: Delhi AQI on Tuesday
- 143: Chennai AQI the same day
- 4: Stages of GRAP
Both sides
- Air quality regulators: Graded curbs help stop the air from turning severe.
- Environmental groups: Emergency steps are not enough; year-round cuts in emissions are needed.
Key terms explained
- Air quality index
- A number from 0 to 500 that shows how polluted the air is.
- Graded Response Action Plan
- A set of anti-pollution steps that get stricter as air quality worsens.
The story so far
- 2021: Commission for Air Quality Management set up by law. Parliament passed a law in 2021 setting up the Commission for Air Quality Management (CAQM) for the National Capital Region and nearby areas. It runs the Graded Response Action Plan.
- 21 Oct 2026: GRAP Stage 1 invoked in Delhi-NCR. CAQM invoked Stage 1 of GRAP across Delhi-NCR on 21 October after air quality worsened.
- Today: Delhi AQI near 'poor'; GRAP-1 in force
Exam notes (UPSC, SSC, Banking, PSC)
- AQI categories: 0–50 good, 51–100 satisfactory, 101–200 moderate, 201–300 poor, 301–400 very poor, 401–500 severe.
- GRAP (Graded Response Action Plan) is enforced in Delhi-NCR by the Commission for Air Quality Management.
- The Central Pollution Control Board (CPCB) publishes India's national air quality index.
- PM2.5 refers to fine particles smaller than 2.5 micrometres that can reach deep into the lungs.
Likely exam question: What is the Graded Response Action Plan, and who enforces it in Delhi-NCR?