Extreme heat is pushing some of India’s poorest workers further into poverty, with income losses of up to 9% for outdoor workers, new research has found. Analysis done by the International Institute for Environment and Development (IIED), and shared exclusively with the Guardian, found that extreme heat is acting as a “poverty multiplier” for hundreds of millions of workers in India’s informal sector. Researchers found that those working in highly physical jobs in sectors such as agriculture, construction and transport lost on average 6.6% of their salaries in 2024 due to extreme heat.

Outdoor workers suffered the most, losing close to 9% of their salary in 2024, amounting to £112 ($151). The economic loss was the highest in the arid desert region of Rajasthan, an area with prolonged heatwaves and a rising death toll due to extreme heat. Informal workers in the region lost equivalent to 8.3% of their income, due to the gruelling effects of extreme heat on the body making them unable to work.

The IIED research estimated that each year, 21.1 working days were lost in India due to extreme heat, an unaffordable loss for many of the 550 million workers in the informal sector. Ritu Bharadwaj, climate finance director at the IIED, said the research showed how extreme heat was deepening poverty and worsening existing structural inequalities in India, which is aiming to be a developed nation in the next two decades. She said: “Heat is quietly pushing these families deeper into poverty.

“As the heat rises, their efficiency goes down, so they earn less. With lower income their food intake falls. And because they cannot afford to stop, they keep working through it, doing lasting damage to their health.

They are paying for a crisis they did nothing to cause, with their health and with their savings.” Human-caused climate breakdown is making every heatwave in the world more intense and more likely to happen. India, a country where nine out of 10 work in the informal economy, could become one of the first places where heatwaves break the human survivability limit, a World Bank report said. The research estimates that heat could cost the Indian economy at least £58bn – equivalent to 2% of its GDP – in a combination of wages lost due to reduced productivity, worksite closures and long-term losses from heat-related illnesses.

The analysis accounts for three ways heat exposure reduces hours worked: heat-related illnesses, a reduction in the capacity of work or maintaining normal productivity, and time lost when workplaces suspend their operations. Informal workers include some of the most socially and economically marginalised people, who lack employment security, obliging them to work through illness and tolerate unsafe conditions. Access to drinking water, shade, rest areas, sanitation and medical support at the worksite was poor, said the report.

Many workers then returned to homes that provided “no relief from heat”. Eight construction workers who spoke to the Guardian all said they had repeatedly fallen ill over the past four months because of the heat, forcing them to miss work and lose income. Some had collapsed and sustained serious injuries but were given no compensation by employers.