Heatwaves And Ground-Level Ozone

Source: Indian Express
GS III: Environmental Pollution and Degradation, Disaster Management

Overview

1. News in Brief
2. Key Findings of the Study
3. How do Heatwaves increase Ozone levels?
4. Climate change and Emerging Threats
5. Recommendations

Why in the News?

A recent study published in the journal Clean Air has found that heatwaves significantly increase ground-level ozone concentrations in India, worsening air pollution and causing serious health impacts.

News in Brief

• The study is titled under “Heatwaves trigger severe surface ozone pollution in India: Regional hotspots, Trends and Health Effects”.
• It is among the first comprehensive assessments of the relationship between heatwaves, ozone pollution, and public health in India.
• Researches have highlighted the heatwaves are not only a direct health hazard but also indirectly increase mortality by enhancing the formation of surface (ground-level) ozone, a harmful air pollutant.

Key Findings of the Study

High Background Ozone Concentration

• Safe ground-level ozone concentration- About 30 ppb (parts per billion).
• Many parts of India already record 50-55 ppb as background levels.

Regional Hotspots 

• Areas most vulnerable include
  • Northwestern India
  • Indo-Gangetic Plain
• These regions already face high pollution, making ozone formation more intense during heatwaves.

Impact on Human 

• Over 830 deaths in 2024 may be attributable to heatwave- induced ozone increases.
• Heatwaves amplify existing health burdens associated with air pollution.

How do Heatwaves increase Ozone levels?

• Accelerated Photochemical Reactions
  • High temperatures increase the chemical reactions between Nitrogen Oxide and Volatile Organic Compounds in the presence of sunlight.
• Enhanced Ozone Formation
  • As heatwave intensity rises,
    • Reaction rates increase
    • More ozone is produced
    • Air pollution events become more intense and remain elevated for longer periods.
• Lasting impact beyond heatwaves
  • According to the study
    • Elevated ozone levels can remain for 3-4 days after a heatwave ends.
    • This extends health risks even beyond the heatwave period.

Impact of Ozone on Human Health

Ground-Level Ozone affects multiple organ systems, particularly

• Respiratory Diseases
  • Chronic Obstructive Pulmonary Disease (COPD)
  • Reduced lung function
  • Asthma aggravation
  • Respiratory inflammation
• Cardiovascular Diseases
  • Ischemic Heart Disease (IHD)
  • Increased cardiovascular stress
• Other Health Concerns
  • Increased risk of premature mortality
  • Potential links with cancer and metabolic disorders.

Key data point

• The State of Global Air Report 2025 estimated around 234,000  COPD deaths in India in 2023, with ozone exposure acting as an aggravating factor.

Climate Change and Emerging Threats

Rising Temperatures

• Climate change is expected to
  • Increase the frequency of heatwaves
  • Raise their intensity and duration

Expansion of Ozone Hotspots

• More regions may experience
• • Higher ozone concentrations
  • Longer exposure periods
  • Greater health risks

Dual impact

• Citizens may face
• • Direct heat stress from  heatwaves.
  • Indirect health damage from elevated ozone pollution

Recommendations

• Expand monitoring of ground-level ozone.
• Improve observation networks across India.
• Agencies such as
  • India Meteorological Department (IMD)
  • Central Pollution Control Board (CPCB)

should regularly track ozone levels and incorporate ozone information into,

• • Health bulletins
  • Heatwave advisories
  • Public health alerts
• Adopt integrated Climate-Air Quality Planning
  • Policies should address
    • Heatwave management
    • Air pollution control
    • Public health preparedness

Conclusion

The increasing link between heatwaves and ozone concentration underscores the need for an integrated approach to safeguard public health and environmental sustainability and to mitigate future risks.

UPSC Prelims Practice Question

Consider the following statements

1. 1. Ground-Level ozone is considered a secondary pollutant.
   2. It is formed through reactions involving Nitrogen Oxides (NOx) and Volatile Organic Compounds (VOCs) in the presence of sunlight.
   3. Heatwaves accelerate photochemical reactions responsible for ozone formation.

Which of the above statements are correct?

a) 1 and 2 only

b) 2 and 3 only

c) 1 and 3 only

d) 1,2, and 3

Answer: d)1,2 and 3

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