Tags:EnvironmentDelhiUPSC
For Prelims: Graded Response Action Plan (GRAP), Air Quality Index (AQI), PM2.5 and PM10, AQI Category, GRAP Stage Imposed, Nodal Body for GRAP, Affected Stations, Current Context
For Mains: Data integrity in pollution monitoring, CAQM's role, GRAP effectiveness, Delhi's winter pollution crisis
Source:
Indian Express
5 facts for one-day exams
SSC, railway, police and teaching exams ask direct questions like these.
- Delhi's AQI was 382 ('Very Poor') on 7 November 2026.
- Stage-III of GRAP was imposed by CAQM in Delhi-NCR.
- 11 out of 59 monitoring stations in Delhi had data gaps.
- GRAP has four stages based on AQI levels.
- CAQM is the statutory body for air quality management in Delhi-NCR.
Why in the news?
Just before Diwali, Delhi's air quality remained 'Very Poor' (AQI 382) for the fifth consecutive day, prompting the Commission for Air Quality Management (CAQM) to impose Stage-III of the Graded Response Action Plan (GRAP). Meanwhile, at least 11 of Delhi's 59 air-quality monitoring stations recorded data gaps, creating blind spots in PM2.5 and PM10 tracking and raising concerns about accurate pollution assessment during a critical period.
Summary
- Delhi's 24-hour average AQI was 382 ('Very Poor') on the fifth consecutive day, expected to worsen to 'Severe' over the weekend.
- CAQM imposed Stage-III emergency measures under GRAP in Delhi-NCR to prevent further air quality deterioration.
- At least 11 monitoring stations had data gaps, including 22 missing hourly PM2.5 readings and 27 missing PM10 readings, with stations like IIT Delhi, Nangloi, and NSIT Dwarka experiencing complete outages.
Highlights
Delhi AQI at 382 (Very Poor)
Air quality remained in the 'Very Poor' category for the fifth consecutive day, with forecasts of worsening to 'Severe' over Diwali weekend.
GRAP Stage-III Emergency Measures
CAQM imposed Stage-III of the Graded Response Action Plan to curb further deterioration of air quality in Delhi-NCR.
Data Gaps in Monitoring
At least 11 stations had missing PM2.5 and PM10 readings, creating blind spots in pollution tracking during a critical period.
Background
Delhi-NCR faces severe air pollution every winter due to stubble burning, vehicular emissions, and meteorological conditions like low wind speed and temperature inversion. The Graded Response Action Plan (GRAP) is a set of emergency measures classified into four stages based on AQI levels: Stage-I (301–400, 'Very Poor'), Stage-II (401–450, 'Severe'), Stage-III (451–500, 'Severe+'), and Stage-IV (>500, 'Emergency'). Stage-III corresponds to AQI in the 451–500 range.
Key Analysis and Impact
The data gaps at 11 monitoring stations, including complete outages at IIT Delhi, Nangloi, and NSIT Dwarka, undermine the accuracy of real-time AQI reporting. Under CPCB's methodology, a station needs at least 16 hourly readings for three pollutants (including PM2.5 or PM10) to calculate a daily AQI. Missing data can lead to 'insufficient data' tags, leaving localised pollution hotspots unrepresented. This is especially concerning during Diwali when fireworks spike particulate levels.
Way Forward
DPCC's standard protocol requires automatic alerts after three consecutive hours of data failure, with nodal officers tracing the cause (server issues, power cuts, sensor choking). Strengthening maintenance protocols and backup power for Continuous Ambient Air Quality Monitoring Stations (CAAQMS) is essential. Expanding the monitoring network and ensuring data redundancy can prevent blind spots during high-pollution episodes.
Background GK
Textbook concepts you need to understand this news
- Graded Response Action Plan (GRAP)
- A set of emergency measures implemented in Delhi-NCR based on AQI levels. Stage-I (AQI 301-400, 'Very Poor'), Stage-II (AQI 401-450, 'Severe'), Stage-III (AQI 451-500, 'Severe+'), Stage-IV (AQI >500, 'Emergency'). Measures include bans on construction, diesel generator use, and truck entry.
- Air Quality Index (AQI)
- A numerical index (0-500) to communicate air pollution levels. Categories: Good (0-50), Satisfactory (51-100), Moderate (101-200), Poor (201-300), Very Poor (301-400), Severe (401-500). Calculated based on eight pollutants, with the highest sub-index determining the overall AQI.
- PM2.5 and PM10
- Particulate matter with diameter less than 2.5 micrometers (PM2.5) and 10 micrometers (PM10). PM2.5 can penetrate deep into lungs and enter the bloodstream, causing respiratory and cardiovascular diseases. PM10 is inhalable and can cause irritation.
Facts to remember
Tap a card to see the answer. Try to recall it first.
How exams will ask this
- Data: Delhi AQI was 382 ('Very Poor') on 7 Nov 2026, fifth consecutive day
- Nodal Body: Commission for Air Quality Management (CAQM) in NCR and Adjoining Areas
- Legal Point: Graded Response Action Plan (GRAP) Stage-III
Don't make this mistake!
They will swap the AQI categories: 'Very Poor' (301–400) is often confused with 'Severe' (401–500). Also, GRAP Stage-III is for 'Severe+' (AQI 451–500), not 'Very Poor' (Stage-I). Remember: Stage-III is invoked when AQI is expected to reach or is already in the 451–500 range.
Write these in mains answers
- Data integrity in pollution monitoring, CAQM's role, GRAP effectiveness, Delhi's winter pollution crisis
Stuck? Get it in one tap
Delhi's air quality was 'Very Poor' (AQI 382) for five days straight before Diwali. To stop it from getting worse, the CAQM body put Stage-III of the GRAP emergency plan into action. At the same time, 11 pollution monitoring stations stopped sending data for some hours, which made it harder to track the real pollution levels accurately.
- Delhi's AQI was 382 ('Very Poor') on 7 November 2026.
- Stage-III of GRAP was imposed by CAQM in Delhi-NCR.
- 11 out of 59 monitoring stations in Delhi had data gaps.
- GRAP has four stages based on AQI levels.
- CAQM is the statutory body for air quality management in Delhi-NCR.
- Environment: Air pollution and its control
- Governance: Environmental governance and regulatory bodies
Related concepts: Graded Response Action Plan (GRAP), Air Quality Index (AQI), PM2.5 and PM10
Practice questions
Pick an answer, then read the explanation.
- Q1Easy
Which body is responsible for implementing the Graded Response Action Plan (GRAP) in Delhi-NCR?
Explanation: The Commission for Air Quality Management (CAQM) in the National Capital Region and Adjoining Areas is the statutory body that imposes GRAP measures. CPCB monitors pollution nationally, DPCC is Delhi's state-level body, and MoEFCC is the overarching ministry, but GRAP implementation is specifically with CAQM.
- Q2Hard
Consider the following statements regarding the air quality situation in Delhi as reported in the news:
- 1.Delhi's 24-hour average AQI was 382, categorised as 'Severe'.
- 2.Stage-III of GRAP was imposed by CAQM to prevent further deterioration.
- 3.At least 11 monitoring stations recorded gaps in particulate pollution data.
Which of the statements given above is/are correct?
Explanation: Statement 1 is incorrect: AQI 382 falls in the 'Very Poor' category (301-400), not 'Severe' (401-500). Statement 2 is correct: CAQM imposed Stage-III emergency measures under GRAP. Statement 3 is correct: 11 stations had data gaps, including missing PM2.5 and PM10 readings.
- Q3Medium
According to the news, how many consecutive days had Delhi's air quality remained in the 'Very Poor' category before the report?
Explanation: The air quality remained in the 'Very Poor' category for the fifth consecutive day.
- Q4Medium
What is the primary concern raised by the data gaps in Delhi's air quality monitoring stations as reported in the news?
Explanation: The CPCB's AQI methodology requires a minimum of 16 hourly readings for at least three pollutants (including PM2.5 or PM10). Missing data leads to 'insufficient data' tags, leaving localised pollution unrepresented. Cost, station reduction, and GRAP delay are not the primary concerns mentioned.
Frequently asked questions
1. What was Delhi's AQI on 7 November 2026?
Delhi's 24-hour average AQI was 382, categorised as 'Very Poor', and it had remained in that category for five consecutive days.
2. Which authority imposed Stage-III of GRAP in Delhi-NCR?
The Commission for Air Quality Management (CAQM) in the National Capital Region and Adjoining Areas imposed Stage-III emergency measures under GRAP.
3. How many monitoring stations in Delhi reported data gaps?
At least 11 of Delhi's 59 air-quality monitoring stations reported gaps in PM2.5 and PM10 readings, including complete outages at IIT Delhi, Nangloi, and NSIT Dwarka.
4. Why are missing hourly readings a concern for AQI calculation?
CPCB's AQI methodology requires a minimum of 16 hourly readings for at least three pollutants (including PM2.5 or PM10) to calculate a station's daily AQI. Missing data can result in 'insufficient data' tags, leaving localised pollution unrepresented.
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- Original7 November 2026 · Read story
