The putrid smell of burning garbage wafts for miles from the landfill on the outskirts of Jammu in a potentially toxic miasma fed by the plastics, industrial, medical and other waste generated by a city of some 740,000 people. But a handful of waste pickers ignore both the fumes and suffocating heat to sort through the rubbish, seeking anything they can sell to earn at best the equivalent of $4 a day.

“If we don’t do this, we don’t get any food to eat,” said 65-year-old Usmaan Shekh. “We try to take a break for a few minutes when it gets too hot, but mostly we just continue till we can’t.”

Shekh and his family are among the estimated 1.5 to 4 million people who scratch out a living searching through India’s waste — and climate change is making a hazardous job more dangerous than ever. In Jammu, a northern Indian city in the Himalayan foothills, temperatures this summer have regularly topped 43 degrees Celsius (about 110 Fahrenheit).

At least one person who died in northern India’s recent heat wave was identified as a garbage picker.

The landfills themselves seethe internally as garbage decomposes, and the rising heat of summer speeds and intensifies the process. That increases emissions of gases such as methane and carbon dioxide that are dangerous to breathe. And almost all landfill fires come in summer, experts say, and can burn for days.