Sangeeta is a construction labourer in the national capital of Delhi. The 32-year old spends almost 10 hours a day carrying bricks, cement, and other construction materials. She earns Rs 400 a day, but if she can put in some extra hours, she can earn up to Rs 600. Sangeeta tries to do that as much as she can as she has two young children to raise.
If winter with its associated pollution problem is not bad enough, the summers can be worse, says Sangeeta. “Most people think that air pollution is only a winter problem. But, the pollution is worse during summer months. Our sufferings multiply manifold with its combination of extreme heat and polluted air,” she told On Air.
Describing the effects of heat and dust, Sangeeta says, “I get palpitations and have difficulty in breathing. My body swells up and I sometimes have chest pain too.” But, she has no option but to continue to work despite everything. “I have to work to educate my kids. Missing work means loss of wages,” adds Sangeeta, who is from Jhansi in Uttar Pradesh (UP) and migrated to Delhi 10 years ago in search of work.
Sangeeta is corroborating exactly what emerging climate science is proving—that extreme temperatures and air pollution combined pose a greater risk to health. Global research studies show that there is a dangerous synergy between heat and air pollution.
When temperatures rise, so do air pollution levels. The Intergovernmental Panel on Climate Change’s (IPCC) Sixth Assessment Report (AR6) concluded this in 2023 after an in-depth assessment of the state of climate change authored and reviewed by hundreds of scientists and experts.
The World Health Organization (WHO) notes: “heat itself increases the levels of some air pollutants: Such pollutants include fine particulate matter (e.g. black carbon) and ozone... Heat stress and high levels of fine particulate matter or ozone can amplify health impacts.”
It isn’t a mere coincidence that February this year was the warmest and most polluted February in Delhi in the last three years. The average maximum temperature in February 2026 was 2.8 degree Celsius above normal and the average air quality index (AQI) was 232—‘poor’ category.
“The combination of heat and polluted air becomes unbearable. I suffer from heavy breathing and headaches. My body is aching all the time, I am constantly fatigued and my skin burns,” said Deepak Mishra, a 40-year-old gig worker, who spends nearly 12 hours a day delivering food parcels in Delhi. Mishra is from Siddharth Nagar in UP and has been working in Delhi for the past five years.
A Dangerous Combination
According to WHO, during heatwaves or hotter periods, levels of ground-level ozone, an often overlooked pollutant, are very high. Rising mercury and sunlight accelerate the chemical reactions between ozone precursors (such as methane, carbon monoxide, volatile organic compounds and nitrogen oxides), leading to higher ground-level ozone formation.
During hotter, dryer and less windy months, ground-level ozone can reach dangerous levels in cities and pose serious health risks, particularly to vulnerable populations like children, pregnant people, outdoor workers, and older adults.
The joint effects of heat stress and air pollution exposures have been documented for cardiovascular and respiratory disease as well as mortality, with the strongest relative effect of heat on respiratory diseases, notes WHO. Heat and increased air pollution concentrations jointly trigger the onset of diseases such as acute myocardial infarctions (heart attack) and exacerbate other noncommunicable diseases, leading to death in extreme cases.
In addition, long-term exposure to air pollution increases heat vulnerability by inducing noncommunicable diseases such as cardiovascular, respiratory and kidney disease. A study published in international journal Nature, in November 2024, shows how high values of heat stress occur in high values of ozone concentrations.
Countries around the world are seeing the correlation between high temperatures and high ozone levels, notes World Resources Institute, an independent research organisation. During a heat wave that spread across Europe in July 2022, the ground-level ozone in Portugal, Spain and Italy all registered at least double the 100 micrograms per cubic meter (µg/m³) deemed safe by the WHO.
That same summer, China also experienced elevated ozone levels during a heat wave. And a recent study made a broader connection between high ozone and high heat in China, based on ozone levels observed between 2014 and 2019.
Economically weaker people, such as daily wager Sangeeta and gig-worker Deepak Mishra, are more at risk. This was also reflected in a study on the effect of heat and ozone on respiratory hospitalisations in California, USA, where lower-income neighbourhoods and areas with high unemployment rates were found to be disproportionately susceptible to the combined impact of heat and ozone.
Air pollutants like ozone and black carbon (soot), which are also known as short-lived climate pollutants as they possess a high warming potential, significantly contribute to climate change. Heat also amplifies dust storms, as higher temperatures can increase the amount of dust lifted into the atmosphere.
Break The Chain
A better understanding of the interplay between high temperatures and air pollution is critical for implementing immediate and long-term solutions to the problem. Cities and countries need to work to weaken the relationship between heat and toxic air.
Public health infrastructure and emergency response systems need to be strengthened. Health centres should be prepared to handle an increased intake of patients seeking medical attention during hot and poor AQI days. Indian cities could learn from Bangkok’s Air Pollution Clinics, which have been set up in several public hospitals in the city to treat respiratory and health issues caused by fine particulate matter. These clinics offer specialised medical treatment, health monitoring, and advice on protecting oneself from high pollution.
Interventions to cool down cities and reduce air pollution should be integrated and prioritised. Urban forests can tackle both the problems. Integration of air pollution forecasting into early warning systems is also the need of the hour.
Outdoor workers need to be protected and covered under a health insurance programme. Last year, the Greater Chennai Corporation launched India's first air-conditioned rest lounges designed specifically for gig workers to provide relief during extreme heatwave conditions. Other cities could set up such facilities.
“In summer, we do not even have access to cold water. We eat our food on the roadside in the heat while breathing in dust. Visiting a doctor means additional financial burden,” complained Mishra. “I am happy to pay a modest fee if the government sets up some cooling centres where we can eat and rest a while during peak summer months,” he said. Mishra earns Rs 22,000 a month.
(With inputs from Abhiveer Gulati.)
(Note: This story was first published in On Air webzine. Read the original story here.)
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