How Extreme Heat Is Hurting People in India’s Slums

Surekha More, a 50-year-old housekeeper in Mumbai, migrated to the city eight years ago after farming turned unprofitable in her village. The move afforded more income for her and her husband—and the hope of a better future for their three children. The family rented a 75-square-foot tenement in a slum in the city, and More now earns about ₹15,000 ($179) a month, cleaning homes and washing dishes in a nearby high-rise.

Moving to the city had seemed like a good decision to the family until this summer, when an intense heat wave engulfed Mumbai, with temperatures nearing 44C (111F) in some parts of the coastal city. More’s home turned into a “furnace,” she says. Everyone in her family fell ill several times over the summer months between March and June. The family suffered from a multitude of heat-related illnesses—dehydration, heat stroke, dizziness, low blood pressure, and heat rashes.

“My children said let’s go back to the village,” says More, who hails from the Ratnagiri region of the western Indian state of Maharashtra. “There’s so much space in the village, so many trees, and breeze—there’s so much breeze. But how will we feed our children if we leave?”

In India, around 65 million people reside in slums, like More. As climate change continues to fuel extreme temperatures, these informal settlements become dangerously hot, with a lack of accessible water, poor sanitation, and overcrowding further increasing residents’ susceptibility to the health impacts of extreme heat.

This year was especially difficult, as India experienced one of its longest and deadliest summers. The record-breaking heat wave in India started early, was more widespread, and lasted longer. It killed 275 people and left tens of thousands ill—and it highlighted how some people are more vulnerable to the intensifying heat than others.

No Relief

Extreme heat, exacerbated by climate change, has been costing lives worldwide. However, its impact is especially pronounced on the urban poor, says Dr. Aditi Mukherji, director of the Climate Change Adaptation and Mitigation Impact Action Platform of CGIAR, an intergovernmental organization focused on food security.

Mukherji states that in extreme heat, crowded living conditions in India’s informal settlements have a devastating impact on residents. Congested tenements have no cooling mechanisms, she says—and people are unable to rest adequately even at night, owing to high nighttime temperatures. In Indian cities, temperatures are no longer dropping after sunset as they did before.

“Even in slums, one finds that some places have air conditioners. So when expenses are done for such luxury items, the casualty is the food for children, which results in malnutrition.”

“I feel that pretty much all governments, including our own, have underestimated the impact that climate change is already having on human populations—and therefore have not taken adequate steps to protect the vulnerable,” says Mukherji.

Health Impacts on Residents of Slums

Thirty-eight-year-old Sangeeta Vishwakarma also resides in a cramped, single-room dwelling in a Mumbai slum with her husband and three children, two boys and a girl. This summer, as the heat warmed up the floor, walls, and furniture in their home, the family could not bear to stay inside. Every few hours, they’d go to a neighbor’s house and cool down in the air conditioning for a few minutes; the electric fan in their own home seemed useless. Soon, all of Vishwakarma’s children started falling ill.

“All three of them developed rashes over their bodies. They’d keep scratching and the rashes got worse. It rained fire this summer,” says Vishwakarma, a tailor. “My younger son, particularly, fell very ill. He developed palm-sized boils all over his body, and I had to refer him to multiple doctors. We paid over ₹2500 ($30) to get him treated. I have very little income, and now, this added expense.”

A survey conducted in Mumbai’s slums found that temperatures in the city’s slums average 6C (42.8F) warmer than neighboring areas. Meanwhile, a 2022 study of the urban poor conducted across four countries, including India, found that many of these residents “effectively live ‘off-grid’ with unreliable access to quality housing, water, electricity, shelter and shade.”

The study also revealed that only 34 percent of slum residents have access to electric fans; 40 percent have electricity for less than 12 hours a day, in addition to a lack of access to water, which causes heat-related illnesses.

Chandrashekhar Prabhu, an urban planner and former chairperson of Maharashtra’s housing authority, says that extreme heat has several health impacts on the people living in slums. Most such homes, according to Prabhu, have tin sheets for roofs, which are cheaper than concrete but heat up the homes, causing immediate health impacts. Some tenements, meanwhile, have asbestos roofs, leading to more long-term complications.

The World Bank estimates that India could soon become one of the first places on the planet where heat waves break the human survivability limit.

“Asbestos is known to cause cancer. Radiation or sun rays falling on the asbestos roof will have [an] impact because it releases toxins and has a long-term effect on children’s lungs,” says Prabhu. “Further, electricity bills are increasing because the fans have to be switched on due to extreme heat. The use of the fridge has become common, and even in slums, one finds that some places have air conditioners. So when expenses are done for such luxury items, the casualty is the food for children, which results in malnutrition.”

The informal nature of slum settlements positions some people in especially hostile locations. Bilal Khan, a Mumbai-based housing rights activist, points to a slum neighborhood in eastern Mumbai, between a dumping ground and smoke-belching industrial chimneys.

“The temperature there is always higher than the average temperature of the city. This is because there’s [the] release of toxic gases from the industries on one side, and on the other side, there is the dumping ground, where waste does not get segregated properly and keeps catching fire,” says Khan. “This was one of the most vulnerable areas to extreme heat this summer, but even here, there was no government support.”

The Way Forward

Climate change has made heat waves 30 times more likely in India. The World Bank estimates that India could soon become one of the first places on the planet where heat waves break the human survivability limit. As the country gets hotter, residents who are crowded into slums and unauthorized residences will be disproportionately affected, say experts like Mukherji. She adds that to mitigate the impact of extreme heat on these vulnerable populations, the government must provide people with heat shelters.

“In addition, cities need to increase their green spaces on an urgent basis and stop encroaching on water bodies for future construction. Most importantly, we need to emit less greenhouse gas in order to stabilize the climate,” says Mukherji.

“If the current emission patterns continue, we are looking at extreme heat that will be unbearable to human bodies.”

Prabhu, meanwhile, believes that the rich can afford to mitigate the impacts of climate change, but the poor have no such privilege. He says that although slums are unplanned and grow organically, the government can use “planning instruments, which can reduce the temperature within by three or four degrees.”

Already facing dire heat risks, India is likely to be the most threatened country in the world by 2030. However, despite the mounting threat, heat waves are still not recognized as a natural disaster in the country. This is also true in the United States, as NPQ reported in July.

Slum dwellers in India continue to suffer. Shubham Chowre, a 23-year-old who sells spices in a Mumbai slum, recalls the case of a local man who succumbed to extreme heat and was found lying on a street outside the slum. “Everybody suffered in the heat this year,” he says, “anybody who lives here.”

According to Mukherji, “If the current emission patterns continue, we are looking at extreme heat that will be unbearable to human bodies, and we can expect more heat-related mortalities than we are already seeing.”