HQ Team
June 16, 2026: Heatwaves across India may have intensified ground-level ozone pollution linked to more than 26,500 deaths in 2024, according to a new study led by researchers at the Indian Institute of Technology (IIT) Kharagpur, India, raising fresh concerns about the compounding health toll of rising temperatures and air pollution.
The study found that surface ozone exposure during heatwave periods was linked to 15,615 deaths from ischaemic heart disease and 10,898 deaths from chronic obstructive pulmonary disease, with surface ozone levels frequently rising to between 85 and 110 micrograms per cubic metre during heatwaves, exceeding World Health Organization guidelines across every region of India studied.
A pollutant that forms in the heat
Ground-level ozone, unlike the protective ozone layer in the stratosphere, is a toxic pollutant at the surface. It is not emitted directly but forms when nitrogen oxides, volatile organic compounds, carbon monoxide and methane react with sunlight, a process that accelerates as temperatures rise.
“Warmer air causes ozone to form faster, so periods with higher temperature, such as during heatwaves, can result in more ozone production, resulting in poorer air quality,” said Pallavi Pant, head of global initiatives at the Health Effects Institute, which publishes the annual State of Global Air report.
Jayanarayanan Kuttippurath, a climate scientist at IIT Kharagpur involved in tropospheric ozone research, has separately noted that changes in weather patterns, rising temperatures, biomass burning and ozone precursor emissions are expected to accelerate the rise in tropical ground-level ozone in regions including India.
Where the risk Is highest
The study identified north-west India, the Indo-Gangetic Plain, north-central India, the north-east, and the western Himalaya as the worst-affected hotspots for heatwave-linked ozone exposure.
Ground-level ozone is known to damage lung tissue and aggravate respiratory illness, while also raising cardiovascular risk. Even short-term exposure can cause coughing, throat irritation, chest tightness, wheezing, difficulty breathing, and pain during deep breaths, according to pulmonary medicine specialists. Researchers have separately linked ozone exposure to low infant birth weight and gestational hypertension in South Asia.
India ranks third globally for ozone pollution exposure, according to the State of Global Air 2025 report, and accounts for a disproportionate share of ozone-linked deaths worldwide. Earlier global estimates attributed 365,000 deaths in 2019 to ozone exposure, with more than 70 per cent of that mortality concentrated in India and China.
Heat and pollution reinforce each other
Heatwaves and high-pollution episodes frequently occur under the same stagnant, high-pressure weather systems that limit air circulation and trap pollutants near the ground, creating a feedback loop in which extreme heat worsens air quality and poor air quality compounds the health burden of heat exposure.
India suffered its longest heatwave since 2010 in 2024, with several states recording daytime temperatures above 40 degrees Celsius for an entire month and more than 44,000 reported cases of heatstroke, according to the Yale Program on Climate Change Communication.
Calls for Integrated Heat and Air Quality Planning
Researchers behind the IIT Kharagpur study are calling for India’s existing Heat Action Plans, currently focused mainly on temperature thresholds and hydration advisories, to integrate ozone forecasting, air-quality health advisories and combined climate-pollution response strategies.
Without such integration, experts warn the health burden from heatwave-driven ozone spikes will be undercounted and under-addressed, even as climate change is expected to make both heatwaves and ground-level ozone pollution more frequent and severe across India’s tropical and urban regions in the coming decades.
