Governments and employers must act swiftly to shield workers from mounting heat stress, according to a joint report released on Friday by the United Nations, the World Health Organization and the World Meteorological Organization. The study is the first comprehensive update on occupational heat exposure since 1969 and warns that climate change is already undermining both health and economic output worldwide. The agencies estimate that more than 2.4 billion people are routinely exposed to excessive temperatures on the job, contributing to roughly 22.85 million heat-related occupational injuries each year. Productivity drops by 2–3% for every degree Celsius above 20°C, the report finds, eroding output in sectors such as agriculture, construction and fisheries that depend heavily on outdoor and manual labour. Medical consequences range from heatstroke and dehydration to kidney failure and neurological disorders, with vulnerable groups—children, older adults and workers in developing economies—facing the greatest risks. “Protection of workers from extreme heat is not just a health imperative but an economic necessity,” WMO Deputy Secretary-General Ko Barrett said at the report’s launch. The authors urge governments to develop region-specific heat-action plans, consider setting legal maximum working temperatures, and improve training for health professionals to recognise heat-related illnesses. They also call for collaboration with unions, employers and public-health experts to design workplace policies that prevent injuries and sustain productivity in a warming world.