Summer air pollution — why the crisis is no longer just a winter story

Syllabus:  General Studies Paper III — Environment (pollution, conservation)

1. What happened

In March 2026, the Commission for Air Quality Management — the statutory body that oversees air quality in and around Delhi — lifted all curbs under the Graded Response Action Plan (the emergency, stage-wise pollution-control system) across the National Capital Region, signalling the end of winter smog. Yet as the heat rose through April and May, the same curbs had to be reimposed. 

Delhi saw 54 days when daily dust levels crossed the safety limit, and 40 days when ozone breached its standard. Clean air, it turns out, is a year-round struggle.

2. Two seasons, two very different kinds of pollution

WINTER POLLUTION VS SUMMER POLLUTION IN INDIAN CITIES

WINTER — THE SMOG SEASON Conditions: low temperatures, still air, and bowl-shaped terrain that traps pollutants near the ground. Main pollutant: fine particulate matter (PM2.5) — tiny particles smaller than 2.5 micrometres. Main sources: burning of crop residue (stubble) and domestic heating.

 

SUMMER — THE DUST-AND-OZONE SEASON Conditions: intense heat, strong winds and direct sunlight. Main pollutants: coarse particulate matter (PM10) — dust below 10 micrometres — and ground-level ozone. Main drivers: hot ‘Loo’ winds, ‘Andhi’ dust storms, construction dust and dust kicked up from broken roads.

 

HOW HARMFUL GROUND-LEVEL OZONE FORMS Nitrogen Oxides (from vehicle exhaust) + Volatile Organic Compounds (from paints, solvents and fuel) + strong sunlight  →  Ozone It is a secondary pollutant — not released by any chimney or tailpipe, but created in the air by a chemical reaction in sunlight.

 

TWO SUMMER WINDS — DO NOT CONFUSE THEM Loo — hot, strong winds that blow across northern India, carrying dust from West Asia and the Thar Desert over long distances. Andhi — localised, downward-rushing dust storms that come with thunderstorms and lift loose dust off the ground.

 

QUICK CONCEPTS →  There are two ozones. Up high = protective (blocks ultraviolet); at ground level = harmful (the summer pollutant). Examiners test this contrast constantly. →  Mind the counts: the Air Quality Index has 6 categories (Good to Severe); the Graded Response Action Plan has 4 stages. Do not interchange the numbers. →  Loo = far-travelling hot winds; Andhi = local dust storms with thunderstorms. The terminology swap is a regular trap.

3. The way forward

• A dedicated summer action plan for every major city (Delhi has run one since 2022).
• Use of the India Meteorological Department’s forecasts to issue early dust-and-ozone alerts so people can limit outdoor exposure.
• Year-round construction dust control — for example Mumbai’s Air Quality Decision Support System, built by the city corporation with the think-tank Council on Energy, Environment and Water.
• Cutting ozone’s ingredients — cleaner vehicles, stricter factory compliance, and simple behaviour nudges such as Delhi’s ‘Red Light On, Engine Off’ campaign to stop idling at traffic signals.

UPSC VALUE BOX
Commission for Air Quality Management	A statutory body created by the Commission for Air Quality Management Act, 2021, to coordinate research, regulation and emergency action on air quality in the National Capital Region. It replaced the earlier Environment Pollution (Prevention and Control) Authority. It enforces the Graded Response Action Plan.
Graded Response Action Plan	A four-stage emergency system: Stage I – Poor, Stage II – Very Poor, Stage III – Severe, Stage IV – Severe-plus, with tighter curbs at each stage.
National Ambient Air Quality Standards	The permissible pollution limits set by the Central Pollution Control Board. The 24-hour limit for coarse dust (PM10) is 100 micrograms per cubic metre; the hourly ozone limit is 180 micrograms per cubic metre.
Good ozone vs bad ozone	Stratospheric ozone (high up) is good — it shields Earth from harmful ultraviolet rays. Ground-level (tropospheric) ozone is bad — it harms the lungs. The summer problem is the bad kind.
Primary vs secondary pollutant	Primary — emitted directly (PM2.5, PM10, Nitrogen Oxides, Sulphur Dioxide, Carbon Monoxide). Secondary — formed in the air by reactions, such as ground-level ozone.
National Clean Air Programme	A national programme of the Ministry of Environment, Forest and Climate Change to cut particulate pollution by up to 40% by 2025-26 across 131 cities that fail to meet air standards.

With reference to summer air pollution in India, consider the following statements:

1. Ground-level ozone is a secondary pollutant formed when nitrogen oxides and volatile organic compounds react in sunlight.
2. The ‘Loo’ refers to localised, downward-rushing dust storms that accompany thunderstorms in northern India.
3. The Commission for Air Quality Management is a statutory body empowered to enforce the Graded Response Action Plan in the National Capital Region.

How many of the above statements are correct?

(a) Only one

(b) Only two

(c) All three

(d) None

ANSWER: (B) ONLY TWO