Table of Contents
Relevance: UPSC: GS Paper III – Environment, Air Pollution, Climate Change, Disaster Management, Urbanisation.
For Prelims:
- PM10, PM2.5, Ozone, NOx, VOCs, GRAP, CAQM, NAAQS, CAAQMS, AQEWS, Dust Storms, Loo, Andhi.
For Mains:
- Urban Air Pollution, Summer Pollution, Photochemical Smog, Public Health, Construction Dust, Vehicular Emissions, Early Warning System, Air Quality Governance.
Why in News?
Although summer is usually seen as a cleaner season compared to winter, several Indian cities recorded serious air pollution episodes in 2026. In Delhi, the Commission for Air Quality Management (CAQM) reimposed Stage-I restrictions under the Graded Response Action Plan (GRAP) in May 2026. This highlighted the emerging concern of summer air pollution in urban India.
What is Summer Air Pollution?
Summer air pollution refers to air quality deterioration during hot months due to pollutants such as PM10 and ground-level ozone.
Unlike winter smog, which is mainly linked with trapped fine particles, summer pollution is driven by:
- Dust storms, Road dust, Construction activity, Vehicular emissions, Industrial emissions, Strong sunlight, High temperature, Ozone formation
Summer Pollution vs Winter Pollution
| Feature | Summer Pollution | Winter Pollution |
| Main Pollutants | Mainly caused by coarse particulate matter (PM10), dust, and ground-level ozone. | Mainly caused by fine particulate matter (PM2.5), dense smog, and smoke particles. |
| Weather Conditions | Heatwaves, strong sunlight, dust storms, dry weather, and fast-moving winds increase pollution. | Cold air, fog, low wind speed, and temperature inversion trap pollutants near the ground. |
| Major Sources | Road dust, construction dust, wind-blown dust, vehicle emissions, and pollutants reacting under sunlight. | Stubble burning, biomass burning for heating, industrial emissions, and trapped vehicular smoke. |
| How Pollution Forms | Dust gets suspended in the air, while strong sunlight helps form ozone through chemical reactions. | Pollutants accumulate because cold and stable air prevents their proper dispersion. |
| Peak Pollution Time | Pollution is usually more severe during midday and hot afternoons, when ozone formation is high. | Pollution is usually more severe during early mornings and late nights, when inversion is stronger. |
| Main Seasonal Factor | High temperature and sunlight-driven atmospheric reactions. | Cold weather, fog, and stagnant air conditions. |
Why Does Ozone Rise in Summer?
Ground-level ozone is not directly emitted from vehicles or factories. It is formed through chemical reactions in the atmosphere.
Ozone forms when:
- Nitrogen oxides (NOx) from vehicles and industries
- Volatile Organic Compounds (VOCs) from vehicle exhaust, paints, solvents and industries
react under strong sunlight and high temperature.
Hot and sunny days create favourable conditions for ozone formation. Ground-level ozone is harmful because it can irritate the lungs and worsen respiratory illnesses.
What Causes PM10 Spikes?
PM10 refers to particulate matter with a diameter of 10 micrometres or less. These are coarser than PM2.5 particles and often come from dust.
Major reasons for PM10 rise in summer include:
- Dust storms
- Dry soil and loose dust
- Construction and demolition activity
- Broken roads
- Vehicle movement on dusty roads
- Industrial emissions
- Local thunderstorms
PM10 levels can remain high for several days during large dust episodes.
Role of Dust Storms
During summer, hot conditions over the Indian subcontinent create a low-pressure zone. This interacts with surrounding high-pressure areas and produces hot, windy conditions.
These winds may carry dust from:
- West Asia
- Thar Desert
- Dry regions of North India
Such winds can raise PM10 levels across large areas.
Two common types of dust-related events are:
1. Loo-type Dust Storms
- Common in North India.
- Hot winds carry dust over long distances.
- They can affect air quality for several days.
2. Andhi
- Short, localised dust storms.
- Often linked with thunderstorms.
- Strong downward air hits the ground and lifts loose dust.
- Usually lasts for a shorter period.
Cities such as Mumbai and Hyderabad may experience dusty episodes due to local thunderstorms.
Role of Human Activities
Natural dust cannot be fully controlled, but human activities worsen the situation.
Important human-made contributors include:
- Construction and demolition work
- Poor dust control at construction sites
- Broken roads
- Road dust resuspension by vehicles
- Traffic emissions
- Industrial emissions
- Waste burning
- Use of paints and solvents
- Idling of vehicles at traffic signals
When winter restrictions are lifted, construction work often resumes. Without proper dust management, it increases PM10 pollution.
Impact on Public Health
Summer pollution can harm public health in several ways.
- PM10 can irritate the nose, throat and lungs.
- Ozone can worsen asthma and other respiratory diseases.
- Children, elderly people and persons with lung diseases are more vulnerable.
- Heatwaves combined with air pollution increase health risks.
- High pollution can reduce outdoor working capacity and quality of life.
Thus, summer pollution is not only an environmental issue but also a public health concern.
Government and Institutional Measures
CAQM and GRAP
The Commission for Air Quality Management uses the Graded Response Action Plan to impose pollution control measures in Delhi-NCR.
Air Quality Early Warning System
Delhi’s Air Quality Early Warning System (AQEWS) was created after severe dust storms and smog episodes. It now provides forecasts for multiple pollutants.
It gives:
- Weather information
- Air quality forecasts
- Pollution alerts
- Three-day AQI forecasts for many Indian cities
The system has also been extended to cities such as Jaipur and Mumbai.
IMD Forecasts
The India Meteorological Department issues weather forecasts several times a day. These can be used to warn citizens about dust storms, heatwaves and poor air quality.
Mumbai AQDSS
The Brihanmumbai Municipal Corporation’s Air Quality Decision Support System, developed with CEEW, helps monitor construction sites. It has helped authorities take measures against more than 1,000 construction sites since October 2025.
Challenges
- Summer pollution receives less attention than winter smog.
- Construction dust control is weak in many cities.
- Road dust management remains poor.
- Vehicle emissions continue to increase ozone-forming gases.
- Industrial compliance is uneven.
- Cities lack summer-specific clean air action plans.
- Public awareness about ozone pollution is low.
- Dust storms are natural, but preparedness is limited.
- Monitoring of VOCs is still weak in many cities.
Way Forward
- Prepare summer-specific clean air action plans for all major cities.
- Use early warning systems to issue dust storm and ozone alerts.
- Enforce dust control at construction and demolition sites.
- Repair broken roads and improve road sweeping.
- Reduce heavy vehicle movement near construction zones.
- Control NOx and VOC emissions from vehicles and industries.
- Promote cleaner public transport and electric mobility.
- Encourage behaviour such as switching off vehicles at red lights.
- Strengthen monitoring of ozone, PM10, NOx and VOCs.
- Link air pollution alerts with public health advisories.
- Treat summer and winter pollution with equal seriousness.
Conclusion
Indian cities are no longer facing air pollution only in winter. Summer brings a different pollution pattern driven by PM10, dust storms, heat and ozone formation.
While natural dust events cannot be fully prevented, their impact can be reduced through forecasting, public alerts and strong control of human-made sources. Cities need year-round clean air strategies that address both winter smog and summer pollution. Effective control of construction dust, road dust, vehicular emissions and industrial pollutants is essential for protecting public health.
UPSC PYQ
Q. Artificial way of causing rainfall to reduce air pollution makes use of
A. Silver iodide and potassium iodide
B. Silver nitrate and potassium iodide
C. Silver iodide and potassium nitrate
D. Silver nitrate and potassium chloride
Answer: A
Explanation
The artificial method of causing rainfall is known as cloud seeding. In this method, certain chemicals are sprayed into clouds to encourage the formation of raindrops.
Silver iodide and potassium iodide act as cloud-condensation nuclei. Water vapour collects around these particles and forms droplets, which later fall as rain.
This method is sometimes used to:
- Increase rainfall in dry regions
- Reduce air pollution by settling dust and particulate matter
- Improve visibility during severe pollution episodes
Options B, C and D are incorrect because silver nitrate, potassium nitrate and potassium chloride are not the standard chemicals used for artificial rainfall in cloud seeding.
CARE MCQ
Q. Which of the following is a major cause of ground-level ozone formation during summer?
A. Direct release of ozone from vehicles
B. Reaction of NOx and VOCs in strong sunlight
C. Freezing of pollutants near the ground
D. Absorption of ozone by urban wetlands
Answer: B
Explanation
Ground-level ozone is a secondary pollutant. It is not directly released from vehicles or industries. It forms when nitrogen oxides (NOx) from vehicles and volatile organic compounds (VOCs) from industries, paints, solvents and fuel emissions react in the presence of strong sunlight.
Additional Information
During summer, high temperature and intense sunlight speed up this chemical reaction. This is why ozone pollution often increases during hot afternoons, especially in urban areas.
FAQs
1. What is summer air pollution?
It is air pollution during hot months, mainly caused by PM10, dust storms and ozone formation.
2. How is it different from winter pollution?
Winter pollution is dominated by PM2.5 and smog, while summer pollution is mainly linked with PM10 and ozone.
3. What is PM10?
PM10 refers to coarse particles with a diameter of 10 micrometres or less.
4. Why does ozone increase in summer?
Ozone forms when NOx and VOCs react under strong sunlight and high temperature.
5. What are VOCs?
VOCs are volatile organic compounds released from fuels, paints, solvents, industries and vehicle exhaust.
6. What are loo and andhi?
Loo is a hot summer wind, while andhi is a short local dust storm often linked with thunderstorms.
