The impact of heatwaves on ozone pollution may be far more serious than previously understood, according to a new study led by researchers at the Indian Institute of Technology (IIT) Kharagpur. Published in npj Clean Air in June 2026, the study found that ozone exposure during heatwaves may have been linked to more than 26,500 deaths across India in 2024. The research analyzed two decades of data (2004-2024) and revealed that rising temperatures not only increase the risk of heat-related illnesses but also intensify the formation of ground-level ozone, a harmful air pollutant associated with respiratory and cardiovascular diseases.

The findings arrive as India continues to experience longer, hotter, and more frequent heatwaves driven by climate change.

Heatwaves Are Making Air Pollution More Dangerous

Most people associate heatwaves with dehydration, heat exhaustion, and heatstroke. However, the study highlights a less visible threat: ozone pollution.

• Ground-level ozone is formed when pollutants such as nitrogen oxides (NOx), volatile organic compounds (VOCs), carbon monoxide, and methane react in sunlight.
• As temperatures rise, these chemical reactions accelerate, leading to higher concentrations of ozone near the Earth’s surface.

Unlike the protective ozone layer high in the atmosphere, ground-level ozone is harmful to human health.

• It can damage lung tissue, worsen asthma, reduce lung function, and increase the risk of heart disease.
• Researchers found that during major heatwave events in 2024, ozone concentrations frequently reached 85-110 micrograms per cubic meter, exceeding World Health Organization (WHO) guidelines across every region of India.

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The Human Cost: More Than 26,500 Deaths

The study estimates that ozone exposure during heatwaves was associated with:

• 15,615 deaths from ischaemic heart disease (IHD).
• 10,898 deaths from chronic obstructive pulmonary disease (COPD).
• More than 26,500 combined deaths linked to heatwave-driven ozone exposure.

To understand the scale of the problem, researchers compared these figures with non-heatwave periods. Before heatwave conditions developed, ozone exposure was associated with only:

• 490 deaths from ischaemic heart disease.
• 342 deaths from COPD.

This dramatic increase highlights the growing impact of heatwaves on ozone pollution and the resulting health burden.

Also Read: Europe Records More Than 200000 Heat-Related Deaths Since 2022

India’s Hotspots for Ozone Pollution

The study identified several regions where ozone pollution became particularly severe during heatwaves:

1. North-West India
2. Indo-Gangetic Plain
3. North-Central India
4. North-East India
5. Western Himalaya

According to the researchers, ozone levels in many of these regions exceeded WHO safety limits by 39% to 45%, while the Western Himalaya recorded peaks reaching 115% above recommended limits.

These areas also experienced some of the longest and most intense heatwave events of 2024.

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Record-Breaking Heat Across India

North India experienced particularly severe heat conditions during May and June 2024.

Some notable observations include:

• North-west India recorded heatwave episodes lasting up to eight consecutive days.
• Temperatures reached 44.12°C during the May heatwave event.
• North-central India experienced multiple heatwaves with temperatures exceeding 44°C.
• Churu in Rajasthan recorded India’s highest temperature of 50.5°C on May 28, 2024.
• Southern states, including Tamil Nadu, interior Karnataka, and Rayalaseema, also experienced severe heatwave conditions.

Researchers partly attributed the severity to the absence of active western disturbances, which often provide temporary cooling relief across northern India.

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Why Ozone and Heatwaves Are a Dangerous Combination

The study explains that heat stress and ozone pollution can amplify each other’s effects.

During extreme heat, the body increases blood circulation to the skin to release excess heat, placing additional stress on the cardiovascular system. At the same time, inhaling ozone triggers inflammation and oxidative stress in the lungs and blood vessels.

For people living with respiratory illnesses such as COPD, the consequences can be severe. Earlier research cited in the study found that COPD mortality risk increases by approximately 1.7% for every 10 micrograms per cubic meter increase in ozone concentrations.

Similarly, ozone exposure can contribute to vascular inflammation, increased blood viscosity, and a higher risk of heart attacks.

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Climate Change Is Making Compound Risks More Common

One of the most important findings is that climate change is creating “compound events” where multiple environmental hazards occur simultaneously.

The impact of heatwaves on ozone pollution demonstrates how rising temperatures can worsen air quality, creating health risks that extend far beyond heat stress alone.

Scientists warn that as global temperatures continue to rise, these combined heat-and-pollution events are likely to become more frequent and more intense.

Key Findings at a Glance

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Why India’s Heat Action Plans Need an Upgrade

The researchers argue that most existing Heat Action Plans focus heavily on preventing heatstroke and dehydration, but often overlook air pollution risks.

To better protect public health, they recommend:

• Integrating ozone forecasting into heatwave warning systems.
• Issuing air-quality health advisories during extreme heat events.
• Developing combined climate and air-pollution response strategies.
• Improving public awareness of ozone-related health risks.
• Strengthening monitoring networks in high-risk regions.

The study concludes that recognizing the impact of heatwaves on ozone pollution will be essential for protecting communities in a warming climate. As heatwaves become more intense and frequent across India, addressing ozone pollution alongside extreme heat could save thousands of lives each year and strengthen the country’s resilience to climate-related health risks.

Also Read: Worst-Case Global Warming Forecast Revised Down To 3.5°C By 2100

Frequently Asked Questions (FAQs)

1. What is ground-level ozone?

Ground-level ozone is a harmful air pollutant formed when sunlight reacts with pollutants such as nitrogen oxides and volatile organic compounds.

2. How many deaths were linked to ozone exposure during heatwaves in India in 2024?

The IIT Kharagpur study estimated more than 26,500 deaths, including 15,615 from ischaemic heart disease and 10,898 from COPD.

3. Which parts of India were most affected?

North-west India, the Indo-Gangetic Plain, north-central India, north-east India, and the western Himalaya experienced the highest ozone levels during heatwaves.

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