Low-income Indian workers, many of them migrants from rural areas hit by climate change, are paying for worsening extreme heat through lost working days and health complications, with the cost equivalent to 2% of national GDP per year, new research shows.The International Institute of Environment and Development (IIED), a London-based think-tank, worked with local organisations to survey around 540 households of informal workers in three Indian cities: Ajmer, Delhi and Agra. Most had migrated from rural areas to find work in industries such as construction, brick-making, garment manufacturing and food packaging.The survey found them struggling through long working days with little access to shade, cooling, rest or water, as well as few toilets for women. And even when they go home, many live in makeshift shelters or airless cramped rooms with barely a single fan, bringing almost no respite.Outdoor workers are losing about 24 days of work a year due to heat, costing them nearly a tenth of their annual earnings, while indoor workers sacrifice roughly 15 days. On top of losing income, they are also bearing the cost of health problems like heat exhaustion, psychological stress and kidney damage brought on by repeated dehydration.If the survey's findings are extrapolated to a national level, the IIED researchers estimate that the decline in productivity and effects of kidney disease combined add up to lost wages of $78 billion each year.