“If we don’t do this, we won’t have food to eat,” said Usmaan Shekh, 65. “We try to rest for a few minutes when it gets too hot, but mostly we just keep going until we can’t do it anymore.”

Mr. Shekh and his family are among an estimated 1.5 to 4 million people who make a living scavenging for trash in India, and climate change is making the work more dangerous than ever. In Jammu, a northern Indian city in the foothills of the Himalayas, temperatures this summer regularly hit 43 degrees Celsius.

At least one person who died in the recent heat wave in northern India has been identified as a waste picker.

Rising summer temperatures speed up the decomposition of trash and make landfills more hazardous, increasing emissions of gases like methane and carbon dioxide, which are dangerous to inhale.

Most landfill fires occur in the summer and can burn for days. At the Jammu landfill, small fires sporadically burn across the massive pile of garbage, creating plumes of toxic smoke.

According to federal government records, India generates at least 62 million tons of waste each year, and some of its landfills are veritable mountains of trash, such as the Ghaziabad landfill outside New Delhi. Although a 2016 law mandates segregation of waste to keep hazardous waste out of landfills, enforcement is poor.

“Since they mostly use their hands, they get contaminated by touching everything from diapers to diabetic syringes,” said Bharati Chaturvedi, founder of the New Delhi-based Chintan Environmental Research and Action Organization.

She said this year's heatwave "is the most catastrophic one can imagine", adding that "it is really sad to see poor people trying to survive somehow, just relying on their bodies and trying to get through this heatwave".

Public health and heat planning experts say people who are forced to work outdoors are at the greatest risk from prolonged exposure to high temperatures. Heat stroke, cardiovascular disease and chronic kidney disease are some of the risks of working outdoors in hot weather.

Waste pickers “are the most vulnerable and are exposed to the impacts of high temperatures,” said Abhiyant Tiwari, head of climate resilience at the Natural Resources Defense Council’s India program.

In New Delhi, some have cut back from eating two meals a day to just one, said Ruksana Begum, a 41-year-old waste picker at the city’s Bhalswa landfill, who work with the Indian capital’s estimated 4.2 million tonnes of waste each year.

“They are trying to avoid work due to the heat, because if they go to work, they will spend more money in hospital than on food,” said Begum.

Geeta Devi, a 55-year-old waste picker who also works at the Bhalswa landfill in New Delhi, said that when she feels dizzy from the heat, she usually seeks shelter and sometimes someone gives her water or food. But she has to work to earn the 150 to 200 rupees ($1.80 to $2.40) a day she needs to buy food for her children.

"It's hard to do my job because of the heat. But I don't have any other job," she said.

Ngoc Anh (according to AP)