Maarg Manthan · Topic 20.15

National Air Quality Index and Graded Response Action Plan for Air Pollution

Environment & Ecology › Protected Areas Lists and Recent Developments in Environment · Topic 20.15

The National Air Quality Index (AQI) was launched on 17 October 2014 under the Swachh Bharat campaign to present air quality in a simple number and colour that the public can understand. It was developed by the Central Pollution Control Board (CPCB) with IIT Kanpur and expert groups. The index covers eight pollutants: PM10, PM2.5, nitrogen dioxide, sulphur dioxide, carbon monoxide, ozone, ammonia and lead. A sub-index is worked out for each pollutant, and the highest sub-index is the AQI; at least three pollutants must be measured, one of which has to be PM2.5 or PM10, and averages are for 24 hours, except 8 hours for carbon monoxide and ozone. The scale has six categories: Good (0 to 50), Satisfactory (51 to 100), Moderately polluted (101 to 200), Poor (201 to 300), Very poor (301 to 400) and Severe (401 to 500). The Graded Response Action Plan (GRAP) is a set of emergency measures for Delhi and the National Capital Region that are enforced in stages as the AQI worsens. It was first notified in 2017, based on a Supreme Court order, and is now run by the Commission for Air Quality Management in NCR and Adjoining Areas (CAQM), a statutory body set up in 2021. In recent versions, Stage I applies for AQI in the poor category (201 to 300), Stage II for very poor (301 to 400), Stage III for severe (401 to 450) and Stage IV for severe plus (above 450), with actions such as dust control, stricter checks on vehicles, stopping construction, restricting polluting vehicles and trucks, and work-from-home advice. Since late 2022, actions can begin on forecasts. Hedge details: thresholds and actions are revised, so check the latest CAQM order.

5 min read · UPSC Prelims · Environment & Ecology · Protected Areas Lists and Recent Developments in Environment

At a Glance

AQI launched 17 October 2014
Pollutants Eight
Categories Six, 0-500
GRAP body CAQM
GRAP stages I to IV
Exam link UPSC Prelims, Environment & Ecology: Protected Areas Lists and Recent Developments in Environment

Where Does It Fit?

This topic follows the Polluter Pays Principle and ties together monitoring and emergency response for air pollution, extending the earlier pollutant list and the general index topic. Previous topic: Polluter Pays Principle. Next topic: Sand Mining Guidelines and Coastal Erosion Issues.

How Does the AQI Work and What Are the GRAP Stages?

Item	Details
AQI	Launched 17 October 2014 by the CPCB with IIT Kanpur; eight pollutants; highest sub-index is the AQI
Good	0 to 50
Satisfactory and Moderate	51 to 100 and 101 to 200
Poor and Very poor	201 to 300 and 301 to 400
Severe	401 to 500
GRAP	Staged emergency actions for Delhi-NCR, first notified in 2017, now under CAQM
Stages	I poor; II very poor; III severe; IV severe plus (above 450), per recent versions

What Actions Come Under GRAP?

Stage I: dust control at construction sites, curbs on open burning, vehicle checks
Stage II: more road sweeping and water sprinkling, curbs on diesel generators, parking fees
Stage III: restrictions on non-essential construction and some older vehicles
Stage IV: stopping entry of polluting trucks, halt on major construction and demolition, work-from-home and school measures
Forecast-based: stages can start before the AQI reaches the level
Agencies: state governments, municipal bodies, traffic police and pollution control boards act
Concern: short-term measure that does not fix source problems
Better fix: long-term cuts in vehicles, industry, dust and crop burning

What Else Should You Remember?

AQI colours: green, light green, yellow, orange, red and maroon
Health messages: each category has health advice
CPCB: also runs the national ambient air monitoring programme
CAAQMS: continuous ambient air quality monitoring stations
SAFAR: System of Air Quality and Weather Forecasting, run by IITM and IMD
NAAQS: limits set in 2009 for 12 pollutants
Difference: NAAQS are standards, and AQI is an index for communication
NCAP: National Clean Air Programme launched in 2019 for 131 non-attainment cities
NCAP target: a cut in PM levels by 2024-26 compared to 2017, as per updated targets
Non-attainment city: a city that fails national standards for five years
CAQM: formed under an Act of 2021 for NCR and nearby areas
CAQM powers: can issue binding directions and penalties
EPCA: the earlier Environment Pollution Control Authority that ran GRAP before CAQM
Supreme Court: monitors Delhi air quality cases
Odd-even: Delhi has tried odd-even vehicle schemes during severe episodes
Stubble burning: a seasonal source in October and November
Winter inversion: cold air traps pollutants close to the ground
Firecrackers: bans in Delhi in winter
Green cess: entry fee on commercial vehicles entering Delhi
Dust control: construction dust rules, anti-smog guns
Real time: public dashboards and mobile apps show AQI
Link to previous: see Polluter Pays Principle
Link to next: see Sand Mining Guidelines and Coastal Erosion Issues
Link to index: see National Air Quality Index and Comprehensive Environmental Pollution Index
Link to sources: see Key Activities and Associated Air Pollutants
Caution: stage thresholds and actions are revised, so check CAQM orders
Exam hint: remember 2014, eight pollutants, six categories and four GRAP stages
AQI limits: The index reports a single worst pollutant, so it can hide the problem of other pollutants, and it depends on the number and place of monitors
Public health use: Schools, hospitals and city bodies use the AQI categories to issue advisories on outdoor activity
GRAP revisions: The plan has been revised several times, including moving some actions to earlier stages to act before smog peaks
Source mix in Delhi: Vehicles, dust, industry, biomass burning and crop residue smoke from neighbouring states all contribute, with the share varying by season
Airshed approach: Pollution crosses state borders, so the commission covers Delhi and parts of Haryana, Punjab, Rajasthan and Uttar Pradesh
Court oversight: The Supreme Court has repeatedly directed the commission and states to enforce GRAP measures

Why Does It Matter for the Exam?

AQI: 2014; six categories
Pollutants: Eight
GRAP: CAQM; four stages
Current affairs link: Delhi winter smog
Common errors: confusing AQI with NAAQS

As an analytical point, GRAP is an emergency tool, and its stages respond to smog episodes rather than remove sources. Real improvement needs steady cuts in vehicle, industrial, dust and biomass emissions across the airshed.

Why Is This Topic Important?

AQI Communicate
GRAP Emergency
Fix Sources

What Came Next?

The next topic covers sand mining guidelines and coastal erosion issues. Next topic: Sand Mining Guidelines and Coastal Erosion Issues.

Key People and Terms

AQI Air Quality Index
GRAP Graded Response Action Plan
CAQM Commission for Air Quality Management
NCAP National Clean Air Programme
CAAQMS Continuous monitoring stations
SAFAR Air quality forecast system

Exam Corner

Points to Remember

AQI launched 2014.
Eight pollutants.
Six categories.
GRAP has four stages.
CAQM formed 2021.

Do Not Confuse With

AQI and NAAQS Index versus standards
GRAP and NCAP Emergency plan versus long-term programme
CAQM and EPCA Statutory commission versus earlier authority

Memory Hook

Fourteen AQI, eight gases; GRAP climbs four stages when smog amasses.

Mains Angle

Questions ask for pollutants, categories and GRAP bodies. These points help.

AQI Communicate
GRAP Stages
Gaps Sources

A Question You May Face

An original practice question, not a past paper question.

“Explain the National Air Quality Index and the Graded Response Action Plan. How effective are they?”

How to Answer

AQI Define.
GRAP Stages.
Body CAQM.
Gaps Sources.

GS Relevance

Prelims: AQI year, pollutants, categories, GRAP stages, CAQM. GS Paper 3: air pollution management.

Frequently Asked Questions

What is the National Air Quality Index?

The National Air Quality Index, launched on 17 October 2014 by the CPCB with IIT Kanpur, converts readings of eight pollutants into a single number and colour from 0 to 500, with six categories from Good to Severe. The highest sub-index among the pollutants gives the AQI, and health advice is attached to each category.

Which pollutants are covered by the AQI?

The AQI covers PM10, PM2.5, nitrogen dioxide, sulphur dioxide, carbon monoxide, ozone, ammonia and lead. At least three pollutants must be measured, including PM2.5 or PM10, and the index uses 24-hour averages, except 8-hour averages for carbon monoxide and ozone.

What is GRAP?

The Graded Response Action Plan is a set of emergency measures for Delhi and the National Capital Region that are applied in stages as air quality worsens. First notified in 2017, it is now run by the Commission for Air Quality Management and has four stages, from poor to severe plus air quality.

Who implements GRAP?

The Commission for Air Quality Management in NCR and Adjoining Areas, a statutory body set up in 2021, orders the stages, which are implemented by state governments, municipal bodies, traffic police and pollution control boards. Before it, the Environment Pollution Control Authority played this role.

Is GRAP enough to solve air pollution?

No. GRAP is an emergency response that reduces peak pollution during smog episodes, but it does not remove the underlying sources. Long-term programmes such as the National Clean Air Programme, cleaner fuels, public transport, dust control and management of crop residue are needed for lasting improvement.

PYQ Practice — Statement Analysis

1 The AQI was launched in 2014.

True

By the CPCB.

2 The AQI uses six pollutants.

False

It uses eight.

3 GRAP has four stages.