Impact of Heatwaves on Ozone Levels

Summary of Findings on Surface Ozone and Health Risks in India

1. Study Overview:

   • Published in npj Clean Air, the study findings highlight the impact of surface ozone levels during heatwaves in India.
   • Conducted by researchers from Kerala University of Fisheries and Ocean Studies and IIT Kharagpur.

2. Ozone Levels:

   • Surface ozone measured during heatwaves reached 85-110 µg/m³, exceeding the World Health Organization (WHO) guideline of 70 µg/m³ across India.
   • Ozone levels subside within three to four days post-heatwave.

3. Impact on Health:

   • The study attributes approximately 26,500 deaths during heatwave days in 2024 to ischaemic heart disease and chronic obstructive pulmonary disease (COPD) due to ozone exposure.
   • Heatwaves contribute roughly 830 additional deaths (490 from heart disease and 342 from COPD).

4. Methodology:

   • Death estimates were modelled based on an increase in risk associated with ozone exposure, utilizing India’s population exceeding one billion.
   • Ozone is formed from sunlight reactions among pollutants, and its harmful effects are exacerbated by high temperatures.

5. Data Collection:

   • Researchers analyzed two decades of temperature records from the India Meteorological Department alongside satellite and global weather datasets.
   • The study identified 188 heatwave events from 2004 to 2024, correlating with significant El Niño episodes in years such as 2010, 2016, 2019, and 2024.

6. Rising Ozone Levels:

   • Notably, the Western Himalayas exhibited the steepest increase in ozone levels, surpassing the WHO guideline by 115% in 2024.

7. Policy Recommendations:

   • The authors call for urgent climate-air quality policy actions to address the intensifying heat-ozone extremes.
   • Relates to recommendations from the 16th Finance Commission (November 2025) to classify heatwaves and lightning as nationally notified disasters, allowing access to the State Disaster Response Fund for relief.

8. Constitutional and Policy References:

   • The study underscores the need for integrated climate and air quality policies to safeguard public health, potentially aligning with the Directive Principles of State Policy (DPSPs) in ensuring a healthy environment (Article 47 of the Indian Constitution).

9. Implications for Future Research:

   • The study emphasizes the need for direct ground-level ozone measurements to improve the accuracy of health impact assessments.
   • It serves as a foundational benchmark for future studies on climate action, air quality management, and public health in India amidst rising temperatures.

This comprehensive assessment underscores the critical intersection of environmental health and climate policy in addressing ongoing public health challenges associated with air pollution in India.